Why You Should NOT Use RAID 5 Storage ( But Use RAID 6! )

RAID 5 is not a good choice for redundancy these days, and likely won't protect you against a disk failure. Here's why you should instead use RAID 6 in your NAS or RAID array!
▼ Join the conversation! ▼
Twitter ▻ / thiojoe
Facebook ▻ / thiojoetv
Instagram ▻ / thiojoe
Website ▻ www.thiojoe.com
▼ More Videos ▼
How Long do Hard Drives Last?: • How Long Do Hard Drive...
How Are Old Movies in 1080p?: • How Can Old Movies be ...
▬▬▬▬My Channels▬▬▬▬
Comedy ▻ / thiojoe
Gaming ▻ / cachegaming
Extra ▻ / @thio
Get cool merchandise: thiojoe.spread...
Support me on Patreon: / thiojoe
---------------------------------------------------------

[@ThioJoeTech]

A lot of people are having trouble understanding that yes, a single URE can indeed cause the entire array to fail to rebuild. Because of the nature of the parity system, it is NOT the same as having a URE on a standalone drive, where only that single file is lost. You need it ALL to rebuild it all. You might be able to send the drives to a data recovery service who could potentially rebuild the array and only lose the files directly using the lost parity data, but that would be very expensive and time consuming, and not necessarily a guarantee. Not to mention that because array rebuilds take so long, and are very very intensive, it drastically increases the chances of having yet another URE in that time, which could completely ruin any chances of any recovery at all. You can google something like "Raid 5 rebuild failure probability calculator" if you don't believe me on the odds. But using 10^14 URE rate drives is extremely risky and you actually are VERY likely to experience a rebuild failure even with small arrays. In any case, when looking to buy drives for a NAS, my suggestion is ONLY buy a drive with a URE rate equal to or better than 1 per 10^15 bits. This can be found by googling for the 'Data Sheet' of the specific model drive you're looking for. It will be called something like "Non-recoverable read errors rate", "Error Rate (non-recoverable)", "Unrecoverable Bit Error Rate (UBER)", or something similar, probably listed along with the 'reliability' specs in the data sheet. I haven't really been able to even find any HDDs with a URE rate better than 10^15. However, with SSDs you can usually find better URE rates. Data sheets for consumer desktop SSDs (Like samsung's EVO/PRO SSD line or Seagate's Barracuda SSD line) don't list URE rates. But Seagate's "Ironwolf" NAS SSD line actually have URE rates of 1 in 10^17, so 100 times better than any HDD I've seen. However those cost several times more than an HDD (right now it's $750 for just a 3.8TB drive).

[@drsquirrel00]

Jeeeez rebuild issues where the whole thing dies is when old RAID cards would just give up. Software doesn't, could lose a few files around that failure (which isn't as likely as any of these calculators say. Rebuilds read from multiple disks too...

[@dennisrkb]

So how does a raid 6 help with ures?

[@accounterz4371]

I have a question. Given your example you have 14TB with 7 drives in RAID 5 parity is split evenly across every one. So that means that each drive has only 2TB/7 dedicated for parity. When rebuilding a failed drive does it mean you need to read remaining DATA plus Parity ( whole 12TB ) or not ( maybe a smaller amount is enough )? What i want to ask is basically how does rebuilding work?

[@davybloggs1564]

@@dennisrkb Watch the video AGAIN!!

[@supershad9855]

I understand that, but according to a thread: "most hardware RAID will abort the reconstruction and some will also mark the array as failed, bringing it down. The rationale is that if an URE happens during a RAID5 rebuild it means some data are lost, so it is better to completely stop the array rather that risking silent data corruption. Note: some hardware RAID (mainly LSI based) will instead puncture the array, allowing the rebuild to proceed while marking the affected sector as unreadable (similar to how Linux software RAID behaves). linux software RAID can be instructed to a) stop the array rebuild (the only behavior of "ancient" MDRAID/kernels builds) or b) continue with the rebuild process marking some LBA as bad/inaccessible. The rationale is that it is better to let the user do his choice: after all, a single URE can be on free space, not affecting data at all (or affecting only unimportant files); ZRAID will show some file as corrupted, but it will continue with the rebuild process (see here for an example). Again, the rationale is that it is better to continue and report back to the user, enabling him to make an informed choice." meaning that its not a big deal if I use Linux software RAID 5? right?

[@believeinheroes]

I would argue that the bigger lesson here isn't to get overly hung up over RAID5 vs RAID6, but to remember not to fully trust either of them and always have a proper backup. A good backup system turns a nightmare into an inconvenience.

[@AA-zq1sx]

100%. A Raid is not a substitute for a backup, no matter how you stripe or parity it. Even raid 60 could have an internal power surge or something and toast all those spinning drives at once... your data NEEDS to be elsewhere, off the raid, if it matters.

[@ColtonBlumhagen]

I know some nutjob who uses 8 SSDs in raid zero. That dude's crazy.

[@ThioJoeTech]

+Colton Blumhagen Well, I'm not familiar with the error rates of SSDs. If they have very low error rates (if at all), then it might be safe. This video kind of assumes the hard drives have a URE of 10^14, but if you have one with 10^15 or even 10^16, you could probably get away with RAID5.

[@ColtonBlumhagen]

Bombersnomore Haha. This guy gets it.

[@ebelray6890]

Yeah, this video goes hand in hand with the "how long do hard drives last" video. But that one doesn't go into the difference between sata, sas and ssd drives and what vendors make the higher quality drives. Unfortunately because of all the low quality production these days all of this makes a difference.

[@ThioJoeTech]

+Ebel Ray I might have a new video coming soon about different types of drives ;)

[@ebelray6890]

+ThioJoeTech i was going to suggest that as a video for you but you beat me to it. Hard drives can give you lots of directions for multiple videos too I think.

[@andrisorinskis5367]

What a load of BC. First of all, explanation for an average home user goes like this: If you build a redundant array with: 2 drives - your only meaningful choice is RAID1 3 drives - your only choice is RAID5 4 drives - RAID5 for capacity vs RAID10 for redundancy. Only starting with 5 drive array you should consider using RAID6. And, of course, you don't lose ALL data with RAID5 disk loss and URE. You lose one file. It might be critical for an enterprise environment, IF they don't make backups. For an average homeuser Joe it means one corrupted photo, or movie. Not the end of the world. And even Joe should make backups of critical data.

[@MarkKoolen]

Andris Orinskis and beside that, if the data is so important you need an offsite backup, so RAID 6 is not needed

[@It762]

Thanks for th einfo. If the controller restored a degraded raid array, will it report any URE's (and affected files?)?

[@ADAM_______]

Andris Orinskis what if you loose an important file that would go un noticed until necessory for use

[@mozarth]

If you have 3 drives and have to put them in an array, you buy another drive to do so. Who even needs to RAID 3 drives in which kind of environment for what purpose anyway?

[@malmstring]

Exactly what I thought also when watching the video. But nevertheless I'm thankful the guy made the video. It's not wrong, just not applicable for me.

[@CoderMonkeyNathan]

2 drives use raid 1, 3-4 drives use Raid 5, 5+ drives use raid 6.

[@MHZ901]

I use Raid 5 for 10 SAS drives

[@jabetajones]

Raid 5 can have u to 16 drives

[@leexgx]

@@jabetajones the amount disks is limited by the nas or server your using

[@jabetajones]

@@leexgx oh ok im kinda new to pcs

[@leexgx]

@@jabetajones the more disks you use the higher chance of a double fault can happen and loss of data (or all data if 2 disks fail) that's where raid6 should be used, but size of the disks also matter as well over say 4TB you should use RAID6 as well (unless you don't mind restoring your data from backup if you have one) if you don't have a backup you must use RAID6 minimise risk of total data loss but you should have critical information backup up (like pictures, personal videos, and documents) The problem with raid 5 it's not very forgiving when your rebuilding the array after a failed disk has been replaced because if another fault happens 1, because of a data error witch will result in Data loss (normally you can still access the remaining unaffected data) 2, a second disk fails and you lose all data with bi way of recovery The statistical probability of 3 faults happening when you got RAID 6 setup is very unlikely (but not impossible just unlikely, but gets more likely as each disks get larger) but raid 6 good enough for quite a long time even with 16Tab disks as 2 disk failures at the same time are rare, as raid controllers and nas boxes do a weekly or monthly raid patrol read and data consistently checks (depending on how they are configured) witch normally weed out problems disks before they suddenly fail

[@falcon56215]

Good source of misinformation. If one drive goes you still have access to the logical disk even if another drive has a read error. Take a backup of the logical drive using Acronis or similar software, replace the defective drives, rebuild the RAID and restore your backup. You wouldn't lose everything as this video states unless you have two full drive failures, but then you should be doing regular backups anyways. RAID is about keeping your data available all the time , not protecting it from loss.

[@elim9054]

People have different storage needs. There isn't a one size fits all solution, and an absolute statement like "RAID 5 is bad, never use it" is just silly even today. RAID 6 _is_ safer for large arrays where more disks means more points of failure, but for smaller arrays RAID 5 is still fine. It may even be preferable because it has better storage efficiency. Besides, you should be backing up data that's important anyway. RAID is only meant for minimizing down time when a drive dies. If you're ever using it by itself as a substitute for a true backup then you're an idiot.

[@JuanSanchez-rb4qu]

Whats the "safety limit" of raid5? at which number of drives it makes more sense to got with raid6? honest question

[@GospelMusicians]

I can confirm that what he is saying is correct. This has just happened to me on Raid 5. Good thing is that I still backup each week, but HE IS ABSOLUTELY CORRECT!!!

[@TheWayOfTheHeart]

This is because you are using consumer devices

[@GospelMusicians]

@@TheWayOfTheHeart NOPE! Using enterprise drives and Areca Chasis.

[@dr.franxx]

are you using raid card too? 🤔 i'm thinking to use some LSI MegaRAID for RAID 5 btw.

[@alexbright7735]

it doesn't matter if the raid fails because you should have a back up of the raid itself.

[@elim9054]

You'd be surprised/depressed how many people think RAID = backups.

[@josephlucas502]

Having an array fail is kind of a big deal, even with backups.

[@Richard25000]

RAID1/10/5/6 is about availability of data not safety of data. I.e. minor failures not causing an interruption of service, not protection from loss of data from drive failure, server failure, building burning down floods threat explosions etc etc etc.

[@aidanjt]

+Joseph Lucas: Only if the downtime is costing you a lot of money. Otherwise, it's not a big deal at all. A mild inconvenience at best.

[@180doman]

For small ammount of disks (like 4 or 6) usefull space / used space ratio is too small to consider RAID 6, you just need to stick with WD Red, Seagate (not Barracudas!) Ironwolf / Constellation and similar kind of disks and you'll be fine. For larger ammounts, you use ZFS anyway to avoid bit rot. The only really dangerous scenarios i see are some instant power failures and thus you need either RAID controller with battery or UPS.

[@Kaleopan]

Good and proper explanation, except i have to wonder about your reasoning why RAID6 is not a futureproof concept (or as drives get bigger). Unless you get two UREs in the same exact sector in both parity segments, you will always be able to rebuild your lost drive by using the readable sector from the other parity segment and this problem does not scale with drive size.

[@wajinshu]

Thank you for this vid. Now I backup my data 'cause of bad sector, tried raid 5 twice and it always have error, will try this raid setup :D

[@travis1240]

I use raid 1 (plus cloud backup). Sure you don't get the storage size advantage of raid 5, but IMO anything worth keeping is worth keeping 3 copies of.

[@Dashcam_istanbul]

I lost a primary domain controller once back in 2003. The raid 5 didn't help, neither did the secondary domain controller. It was a huge mess. I had to accept defeat and rebuild everything from scratch in two weeks with the help of a friend. Slept at the office for that time. So now I am a bit skeptical to all redundancy systems :)

[@testingmailbox1394]

For the record, raid 5 is still fine for small arrays like an executive workstation for your CEO. His premise here is that you're using a very large array like in a NAS, Backup array, or Data Center

[@AA-zq1sx]

NAS isn't "very large" ... certainly nothing like a data center. It's standard practice for people who do content creation and basic video projects. An 8TB NAS is hardly a huge amount of storage for a KZbinr/Vlogger.

[@Tyler75D]

I've been using a 12 drive Linux Software RAID5 setup the past 10 years. Gradually growing and replacing drives (from 8x200GB to my current 12x2TB). Although I agree with you that RAID6 would be safer, I've never experienced the problems you're describing. I've had 1 drive failing periodically, and replaced maybe 4-5 drives in total (due to failed/dead drives) during the same time period. This is data that I am comfortable loosing, although I would prefer not to. The worst problem I've encountered during this time, is the failing of a controller, where symptoms indicate that multiple drives are lost. But thanks to Software RAID, I'm not bound to a specific hardware disk controller. Which makes it easy to rebuild or even move the entire array to different hardware. So if I encounter the bad sector issue I'll report back when that happens, although I haven't seen a bad sector since the mid 90s

[@daisyduck8593]

I have read that for a raid with multiple hard drives next to each other, you should only use NAS or Enterprise hard drives as they have vibration detection. Because cheap hard disks without vibration detection are actually only intended to be alone in the PC case or individually in an external case.

[@ChaJ67]

This is a topic at work as we deal with a lot of data. So the answer is much more complicated. For some more to chew on: 1. When dealing with large amounts of data with many mechanical drives the answer typically comes down to ZFS RAID-Z level 2, which is somewhat similar to RAID except more check sums in more places, CoW, snapshots, etc. Plus flash based cache drives as RAID-Z is not the fastest thing in the world on mechanical drives. 2. For small arrays, a few big things are out there often favoring RAID 5. You can find reliability reports on many drives and avoid the known bad lines of drives. You can look at SMART data and pull a drive as soon as it starts going bad. As this is usually a slow process, most competent admins pull drives long before they actually fail and enterprise drive vendors usually take back drives even if they have one remapped sector. You can use hot swap as often the double fault happens when you power down a system. You can buy drives in a staggered fashion as sometimes sequential serial numbers in your array lead to drives failing close together in time, which is the last thing you want in a RAID. Flash drives if you look around will sometimes have RAIN, which is NAND level RAID. Flash also will often fail into read only mode, giving you a chance to copy over to a new drive, but not always. However flash in a RAID tends to get beat on more both because RAID controllers don't support TRIM and if you are using throwing money into a flash array, it is probably because you beat on the system a lot more than the average bear. However this wear concern can be addressed with higher endurance flash at a higher cost. For example my main home flash array with Crucial MX500 drives should burn out its flash in about 6 years at the rate I am currently grinding away at it, which is about how long my older flash drives on low use systems failed due to old age, however for twice the cost I could get SSDs with 10-100x the endurance and never come close to burning them out before they failed due to old age. 3. With any data storage system, you should not completely rely on the RAID to save you. Someone might delete important files and RAID does not stop file deletion. Someone might try updates that go horribly wrong. A cooling fan may fail and the whole array bakes to death. The computer with RAID array might get stolen or lost to a fire. Or like the other day with a software RAID 5 a power loss caused the array to scramble while the hardware RAID on the same system was fine. I have also seen arrays lost when the power supply in the box (often cheap NAS) fails and fries all of the electronics in the process. I have seen all of the hard drives seize at the same time after many months of running because the drive manufacture used the wrong lubricant, so once the drives stopped spinning, in this case routine maintenance, they never spun again.

[@AA-zq1sx]

100%. A Raid is not a substitute for a backup, no matter how you stripe or parity it. Even raid 60 could have an internal power surge or something and toast all those spinning drives at once... your data NEEDS to be elsewhere, off the raid, if it matters.

[@Call_Me_David]

Raid 6 doesn't sound like a good option if you're looking to build a four drive array like I am. I'm looking to build a four drive setup using 3, 4 or 5tb drives, but I don't want to loose the storage of two drives, so raid 5 is really the only option. If I was fine with only having two drives worth of space, may as well go raid 10.

[@ClarkLaChance]

But how do I download more raids?

[@harr1s2011]

+Clark Epic You download a copy of Windows and make as many (virtual) RAID's as you like.

[@Oscar4u69]

+Clark Epic i think you can use ramdisk you can download it from amd

[@ThioJoeTech]

Unfortunately you can't download extra raids like you can with more rams

[@vicr123]

+ThioJoeTech Wrong channel to reply from, should have been main channel (would have made more sense) :)

[@martin.klouse]

You need to write a letter to the president asking for a download link. Also works for free money.

[@tangofan4u]

There is something I don't understand about this: Assume you were to use 12TB HDDs with one URE at every 10^14 bits, your probability of an URE would approach 100% during a RAID-5 rebuild. However it would also approach 100% during a RAID-6 rebuild, because every HDD itself would likely have at least one URE. So no matter how many parity HDDs you use, you are always hosed and thus RAID-6 would give you anything over RAID-5. What am I missing here?

[@AA-zq1sx]

The parity file is duplicated. That's the critical part.

[@Hans-gb4mv]

Tripple partiy will never come. With the increase in disk sizes we are running into the limits of what RAID can do with parity. Rebuilding huge arrays simply takes too long and is no longer worth it. If rebuilding takes over a week it simply takes too long. RAID5 is not a bad choice, depending on your use case. You've taken a very specific use case where the capacity of the array equals the URE to say that you are statistically certain that one of the drives will have a URE. While I did not study statistics in school, I do doubt you can simply state it like that. You have 6 remaining drives, each with 10^14 bits so it wouldn't surprise me that you can say in this case that the actual value would be 6*10^14. And what would you do with the new 14TB drives that got just announced. If they also have a URE of 10^14 you statistically will always have an URE on the drive. Not use it? (welcome to the wonderfull world of statistics). And to add a few more things: - The URE is the avg over the lifespan of a drive. It might be possible that you read 1000TB of a drive without a single URE and then all of a sudden you get a multitude of them resulting in the avg of once every 12TB - The URE is a single bit in a sector. Every sector has a CRC that gets updated on every write (how else would you know about the error?) The URE can even be in the CRC data. Most bit errors happen on write anyway and the system will always read back written data to confirm it is written OK, further diminishing the chance of having bad data due to a bad bit. - On modern drives with 4k sectors if you write small amounts of information the drive will pad the sector with the same information, as long as it is smaller than 2k, thus making a copy of the same file making it more likely that the information can be recovered. And lastly, let's not forget: RAID is not a substitute for backups. If you do come across a URE, you should still be able to recover the unrecoverable data from your backups.

[@depravedone]

I've rebuilt a few dozen 20~30TB RAID 6 arrays without a single rebuild failure. RAID 6 is solid. This has always been with Adaptec controllers (51645, 6805, 71605 etc.)

[@bortsimpsonx]

Normally if you create a raid set you also set a spare drive so it can start rebuilding the raid asap. Depending the raid you want/need it will be better one or the other. Also keeping in mind performance of course

[@91rahulgandhi]

awesome video!, but I think you should of also include RAID 10 as well. because it gives you best of both RAID 0 & 1.

[@mahimahoo9178]

Wait is this the non troll channel?

[@mahimahoo9178]

Adolf Hitler Okay, thanks Hitler. You always got my back.

[@SubLowForty]

I'm Not Chase I enjoyed this conversation immensely ^^^

[@stephenfwadsworth9565]

Nope, but funny. Subject to Satire, being part of your sense of humour? No but it is like phoning tech support and speaking to two technicians, a day apart. Explain the Lion? Since you need the attention? :) Then go back to Facebook, please. :)

[@gavinwinter8757]

This is 6 years old, but is as misunderstood now as it was then, and when this was first floated around 2009. The HDD data sheet specs for bit read errors are a statistical expression of failure rates [and a poor way to express it], not a performance specification. RAID 5 is absolutely fine - drives fail at around 1% PA for the cohort of drives used in such arrays. Another way to look at is [also misleading but uses the same logic as the RAID 5 is dead concept] if 1 HDD from a 6 HDD R5 array fails - that event itself is way way beyond the URE rate that 6 drives collectively would have ever experienced if we believe a plain text reading of the URE spec.

[@Straatbrak]

Ok so I can use RAID 5. Thanks

[@anocco]

I don't agree, in many cases (at home, etc..) a NAS with 3 drives RAID 5 it's good enough. If you want to assure to don't lose data you schedule a regular backup of your NAS into an external drive. This is the best practice

[@tomashton1265]

I use RAID 5 for all my servers and never had a issue when replacing a dead HDD. Touch Wood.

[@MHZ901]

Touch SSD

[@kevinsky86]

I rarely have dead drives to begin with. One or two in the last fifteen years. Just periodically replace them. Virtualization has made the vast majority of my hardware super easy to replace. Move guests to different box. Box can be turned off.

[@mesaber86]

@@kevinsky86 How odd you rarely have any dead drives if you periodically replace em. *insert meme*

[@knwr]

@@mesaber86 it sounds like periodically is being used to define 1/2 failures, not uncovering hidden secret failures. Although I could be wrong, only Kevin de Bie really knows how many drives have failed.

[@brianjones8432]

"I use RAID 5 for all my servers and never had a issue when replacing a dead HDD." Famous last words before cold sweats, tons of sleep deprivation, and data loss.... If one of your other drives fails during recovery you're SOL......smh

[@haraldschuster3067]

I have yet to see a RAID controller that stopped rebuilding a disk because of ONE read error. So far I only managed to get a corrupted file as a result but the rest was recovered nicely. So the big question is: Is ONE defective file (which is possible, but not guaranteed to happen) worth an extra disk (and a bigger NAS system in case you need more than 4 drives)?

[@Sherwin724]

can you make a video showing how to download more cpu cores?

[@oofig]

HAHA U GET REDDIT WOOSH

[@moreseun]

lol

[@hapkidokid1]

You are aware that you lose performance in a raid 6 array. I work for an MSP that specializes in dental I.T. These places due to Canadian standards must keep data for patients for 10 years. Every one of our 2000 servers in play all have a raid 5 arrry and for the most part there are no issues. Now keep on mind even with a raid array we still run a cloud and on site back up of the host and the DC VM and Server VM. You should never %100 rely on you raid array.

[@hendrikschepkens6455]

i can no longer take this guy seriously i just assume its bullish

[@jonaskonrad]

why are so many disabled people in the youtube comments

[@christophesch4070]

who can??!

[@SamAndrew27]

Right, but who's making the distinction...

[@amirite]

WOAH I am literally just discovering this fact!!! Why isn't this video fake????

[@another3997]

Vince Cropani If you listen to what he is actually saying, he is correct. The parity drive can only make up for failure or errors on one drive. If you have a drive failure and then find reading errors on another, you will likely lose data. RAID 6 is designed to help overcome this.

[@stoobeedoo]

I have an Asustor 2404TE, one of the very early line of Ausstor NAS that had an early Atom CPU. It had a 4x3TB setup (WD Reds) at RAID-5. The 3pin cable conencted to it wore and there was a power surge that caused damage to one of my drives. Eventually it was reporting a lot of rear errors on the drive, which started small then began to build up. I don't know if they were UREs, but there were many. The system rebuilt the raid twice with no issues during this time. I then replaced the faulty drive (4) with another, the RAID rebuilt. That was back in 2017 and there's been no issues since, though the other drives will need replacing soon. So while there's a risk of URE it's incredibly low, and your drive will likely start reporting errors before this stage, at which point you should replace the faulty drive ASAP. Raid 6 has more redundancy, but I don't think it makes up for the exorbitant cost to get the same level of storage. I am planning to get a new ASUSTOR with a 4x4TB setup. Obviously my rebuild risk is higher, but I don't think it's worth me forking out another $400ish just for the same level of storage.

[@bryanhardesty5609]

I understand RAID 6 has a slower write speed than RAID 5. What about RAID 5 plus a hot-swap drive? That's what I'm doing right now. So if a drive goes bad the hot-swap kicks in and it rebuilding the array automatically. I replace the bad drive with a new one and it becomes my new hot-swap. You get part of the benefit of RAID 6 (although not the exact same) without the performance hits of 6 vs 5.

[@davebing11]

all that means is less time is required to discover that a drive has died. If you have any errors during a raid 5 rebuild, data is toast. Raid 6 allows the data to be protected during a raid 5 rebuild

[@kirksanders883]

With 4 6TB disks I've gone with Raid 5 due to not wanting to spend money on a NAS with more than 4 drives and I need most of the 18TB for Personal Photos/Video/TV Recordings/Music, Movie, TV Disk rips. I backup that the data to two external inexpensive Costco 8tb external drives and also backup critical personal photos and videos a 3rd time to another older system I use as an NVR. Those criticals are then stored on additional portable HDDs that go off-site. I appreciate the information in this video and it has put me on alert. It was presented very well, but I believe it is more of a balance of cost, how redundant your backups are, your need for that extra space, and your willingness to rebuild an entire array if you have it fail completely on the rebuild of the single drive. If I could afford a 6 drive NAS I'd be using raid 6, but I truly believed HDD costs would've come down farther than they have. It's just not worth it to pay another $1500+ at this time just so I can say I can lose two drives. When my NAS does need upgrading again I'll have to revisit Raid 6 and hopefully either my appetite for space has subsided or the cost per TB comes down.

[@eddeig]

Great video. I'll be using RAID 6 on my new storage! Many thanks for your effort, cheers!

[@falcon81701]

So for a 4bay NAS, would Raid 1+0 be a better option than raid 6?

[@bepis2679]

ZFS is the future of drive arrays.

[@llothar68]

It's total overkill for desktop systems or small servers.

[@th00ht]

It-s not. My home build 4 disk NAS, primarily used for archiving is build on ZFS which has one big advantage over RAID5. It is protected against bit-rot.

[@billcouper1289]

how is it a big advantage? bit-rot is not undetectable and between smart and filesystem protection you'd have to be incredibly unlucky to end up with a corrupted file - you DO have backups right? and i have never heard of a raid array failing due to bit-rot. but go on, all you zfs ppl just keep saying it over and over, it's not going to make zfs any better you know.

[@th00ht]

I've had my share of corrupted files on large storage (2TB) devices.

[@llothar68]

th00ht Every harddisk has already some pretty good ECC algorithm against bitrot, i really think it's most likely a ZFS marketing strategy and not a real problem for the majority of people.

[@scottishphotography9680]

Thanks, lot's of people say don't use RAID5, you're the first to explain why!

[@davidc5027]

eh... Delving into a grey area here... For most home users, Raid 5 is just fine, even if the array is larger than 12 TB. Lets say worse case scenario, and you loose a disk, and error correction failed to detect the URE, and during re-build the URE is discovered hence fails to rebuild. There is a another option that Joe fails to mention. Actually, there's 4 or 5 other options, but I'm not going to get into them right now. The easiest thing to do if your Raid array fails to rebuild due to a URE, is to copy off the data. Yes, that means you will likely have to buy a couple of huge drives, and stand up temporary storage, which is a pain, but you will be able to copy the data off. Folks... Don't freak out over URE. Yes, the risk is there, but if you're buying quality drives the chances for URE is even smaller than what Joe stated. If you're Enterprise or your data is that important I figure you're going to go with 6 or Raid 10 anyway..... So, my point is just geared to the folks at home that may not have critical data and don't want to loose that additional disk space by going to Raid 6.

[@jordanbanko5347]

What are the other options he fails to mention? I’m trying to find a good safe way to back up my data and thought raid was the answer. After reading the comments, however, I’m seeing that it is not.

[@leexgx]

What you just said there is no simple task for home user, where if you had been using RAID6 to begin with a URE won't be a problem (or second disk fail) just replace the disk and let it rebuild It be nice if Synology used 5 bay NAS by default (no 4 bay nas's) from 2 bay ones to cover the extra disk needed for RAID6/SHR2

[@tomwells8093]

Also UREs can just be skipped over. Unlikely you will get more than a handful. So worst case you rebuild the array with 5 files missing. Obviously if you have a backup then its fine also. Easily encounter same problem with RAID 6 with UREs. So video isn't exactly telling the whole truth. Rebuilds can be hard on drives so possible it can lead to other disk failures during it, unlikely but can happen. This video hides the full facts and tells only a narrative that he wants you to hear

[@paulzielinski1326]

Nice video, As a systems engineer Raid 5 and or Raid 50 is discouraged partly because of what you mentioned in your video, but also what a drive fails in Raid 5 and or 50, the drives spin up to full read speed when the bad drive is replaced. This full read speed increases the chances of the other drives failing during the rebuild process and until the new drive is completely rebuilt your chances of failure are much higher. The errors that will leave a drive useless are much more that what was mentioned in your video.

[@paulzielinski1326]

Let me further comment, that raid 6 and or raid 60 is preferred, having a third drive with parity, as far as I know, is not a thing yet, because it is just as easy to add a hot spare. So if you have a raid 6 or 60 and a drive fails, the system automatically starts to rebuild the hot spare drive. You can have as many hot spares as you want. In the event that a second drive fails during the rebuild of a raid 6 or 60, either a second hot spare can be deployed automatically or a system admin can wait to replace it.

[@ted_maul]

I'm not sure this advice is particularly helpful for a SOHO user. His implication is that that your RAID array somehow forms part of your backup strategy (or perhaps even *is* your backup strategy) which in itself is a poor message to convey. I really can't see too much issue with RAID 5 + proper backups. How many SOHO environments need 2 levels of redundancy unless in special situations?

[@jordanbanko5347]

Mark Browell what do you use besides raid to backup your data?

[@themoody1337]

I love your channel. Its just so awesome how u teach me things in an interessting way! And quick. It fits in every day and im Happy to have u subscribed! Greeting from germany!!!

[@OnTarget100]

I had a major RAID 5 failure. I lost 15TB worth of data 5 disks. I've now got 3 NAS with a total of 85TB each running RAID 6 and being backed up in realtime to each other. When my RAID 5 did crash and I went to install the replacement drive that is when the shit got real and the whole RAID died. I had to use a RAID recovery software to retrieve my data most of it but not all. Enough to get me out of hot water. There are two kinds of people on earth people who have lost data and learned from it and other who have yet to learn. Peace from Sydney Australia

[@flubblefruitstick]

+OnTarget100 Dude thanks, you just crystallized my decision between RAID 5 and RAID 1.

[@downthegardenpath]

OnTarget100 More fool you for not having a backup. I use two RAID 5 arrays, one backs up to the other nightly. The first array also backs up to cloud storage as soon as I write to it. I do this because I don't want to loose data, not because I learned the hard way

[@penguin12902]

If you follow the 3-2-1 rule you shouldn't ever lose data.

[@johnmadsen37]

Must have been some valuable data lost to over compensate like that. I’ve lost data too, usually when upgrading OSS. By my own mistake of thinking I’ve completely copied data over , then resetting the disks for the new os. I’ve never lost data due to a disk failure. I also never use cheap disks. Only HGST hard disks and Samsung SSDs. I’ve had hard drives fail but only WS and toshiba. You’re smart and have the budget to have not only redundancy for disks but also separate enclosures. Very cool. I’m in the process of replacing all my bad Disha from 8 4TB to 10TB. At 350$ each, it’s damn expensive. But, like you, I have valuable or priceless (old work files I can never get back), so I get it. For sure. Photos fade, digitals do not ... music leaves popularity thus impossible download, same with films and tv shoes. What bad devices did you do with?

[@BasNunnikhoven]

but with a professional 4 or 8 bay server rigg it should be fine right? For raid 5?

[@cuteswan]

I remember when this video was released about a month after I bought a WD RAID 5 unit (an EX4). In May one drive failed, and when I put in the replacement and started the rebuild - of course - another drive failed… then a third failed diagnostics. The $20 warranty was really worth it since I got a full refund at least. Still, annoying. Now I'll take TJ's advice. He was right. (Maybe I'll even tape some dead batteries to the ends of my network cables too. 😉 )

[@Earlzo2325]

excellent content from the Michael Cera of Tech :D

[@MagneBugten]

Do not use RAID for storage! If you are using raid 6 you are "walking on thin ice" as you say. I'm not saying you didn't do your homework, Joe, everything you said was right. However, RAID by itself is not a good idea for a storage system, and you actually touch on the right idea why: read errors and bit rot. Take this as an example: When you have your RAID 6 set up and go to look at an image you stored last Christmas, what is to say that your storage array gives back exactly what you put in? Fine the disks can have some degree of error correction but what happens when, over time, some bits flip because of a cosmic ray hit or something like that? Well, you get the wrong data back. Mostly it would be a pixel block in a jpeg that turns a shade darker or something unnoticeable like that, because that is where the probability lies. But once in a while, something worse could happen causing the loss of that image, or video for instance. So what's the solution then? Well, it is the file system that you employ. BTRFS and ZFS are two of these on the linux platform and ReFS by microsoft for servers is a relatively new one. The important part here is that these file system supports something that is called checksums which helps the file system figure out if something is broken. And without going into too much detail, makes the file system able to get the correct data from a pairity block (yes a raid but inside the file system). Go check out TekEnterprise's video "RAID: Obsolete?" for more info on that... So what does this mean for the average user or slightly data hungry users like photographers and people who like to download a lot of things from the internet all the time...? It means don't. Get a single big drive, and designate it as your backup drive. Then pay for a service like Amazon Glacier or Backblaze (i like backblaze's business model). What raid is good for by itself are things like cashing and fast access memory that is none-vital. It is NOT AT ALL a backup solution. Gamers (and even photographers) who want quicker loading times can use SSD's in RAID (as long as vital data is backed up). And if they need more of that ultra fast storage they can get 4 ssd's and put them in RAID5 so that their downtime would potentially be less if a drive fails. damnit i wrote too much again...

[@IqbalHamid]

Sorry, you are not making sense. Do you mean that we should not regard RAID as an alternative to backup? If so, I agree with you. But you appear to be saying something different. You are advising to not use RAID at all for STORAGE?? What on earth do you mean by that? What are hard disks used for if not for storage? You are right to acknowledge bit-rot. However, it is not clear, as there is insufficient data, to know how common this is. I have experienced symptoms of bit-rot: a total of 4 x 2Mb jpegs with half the image missing or discoloured out of a terrabyte's worth of storage over three years. I would regard that as a significant frequency, except in my case, closer inspection revealed these symptoms were more likely to have been caused by corruption during transfer of data. Looking at the binary contents using a Hex Viewer revealed that the it wasn't bit-flips that had caused the symptoms in my case because the replaced data was structured, ordered and massive. I could read text and settings in the corrupted regions of those files. I believe that the protection from bit-rot comes only by using resilient file systems like the ones you have mentioned. I am therefore in agreement with bits of what you are saying. However, are you also saying that implementing RAID is bad for the health of the data, ie it will be bad for the integrity of the data? How can this be? I can understand that bit-rot, undetected by the error correction systems of the hard drive (eg SMART) can lead to the corruption persisting. But this would be the case even if RAID were not implemented. Therefore, best practice would be to complement RAID with regular backups. Is this what you are trying to say? You don't appear to be saying this. You appear to be saying that RAID is bad for the health and integrity of the data. Please explain why you believe this.

[@MagneBugten]

IqbalHamid Ok you appear to have done your homework so i will skip the basics: The redundancy alone is not enough to protect against data loss. tec syndicate goes over this. If you put some data on a raid (and we are not talking about raid 1 here) and some of the data on the active blocks get corrupted (either by bit-rot or by transfer problems and cut offs), the array will serve you the wrong data. a resilient file system would detect that there was an error and correct for it and serve you the correct data. Best practice is to use single drives, and back them up to a cloud service. because its cheaper. If you value some data, download it to two separate drives, OR keep your pictures on your memory card or phone until that backup is done. That the cheapest too. I say dont use raid for storage at all. And i say that because the people watching this video considering to use a raid array have no need for one, because they don't generally understand the drawbacks. A lot of people on youtube alone has suffered from raid failures due to inadequate understanding. cloud storage is so cheap, people would laugh at you ten years ago if you said you could store terrabytes per month for $5. does this answer your question?

[@cryptochrome_original]

your statement is only valid if you are mistaking RAID for backups. Since RAID is not backup, your statement is not valid at all. RAID is not designed to protect from data loss. It is designed to protect from downtime due to hardware failure. RAID is a must in any storage array. To protect from data loss, you create backups.

[@llothar68]

Wrong. Drives have checksums on all sectors, so the drives can detect bitrot, then it's up to the RAID controller to pick the other correct software. Even a FAT filesystem can do this. I only use RAID 1 or 10. But seriously RAID is a 40 year old technology and today it should be build into the filesystem or on servers even in the application software layer.

[@bobfl42]

As usual very interesting. I have an external drive with 2 X 2 GB drives in RAID 1 it meets my needs and budget. Perhaps in future you could talk about building an external RAID array.

[@craigschannel4042]

another thing to take note is when a RAID 5 is rebuilding it works your existing(possibley near EOL) drives harder to re build the array. I have had 2 drives fail on me in the middle of a rebuild

[@daisyduck8593]

When you want to be extremely save you even need to build a backup archive... Because bad data can be copied over time ? So you keep a backup drive f.e. every 3 years... After 30 years you have an archive with 10 drives... When ever you find out a data is broken. Maybe you will load it from an older drive... Is that true what I am writing ?

[@Halawany]

What's wrong with raid one 🤷🏻‍♂️

[@bertramusb8162]

Usable space cost

[@sephirotic87]

I have been using a 4 disk array Raid 5 for 6 years now. I switched over 8 drivers through it in all these years and had no problems whatsoever. As long as you understand the risks and that RAID is no substitute for backup, there is absolutely no problem using RAID 5, by the contrary, the big benefit is the low storage lost, (only 25% for 4 drives, instead of 50% for Raid 10). Raid 6 is better, but only for more drives. For 4 drives, the failure chance is pretty reasonable for the gains in storage and read performance. Raid 5 is particular good for video editing as it gives 3~3.5x times the linear throughput which is important for accessing large videos. And video writing does not need much seeking and randon writes.

[@Baldroega]

well you can just use RAID 10, simple, efective and reliable.. i know you have less space.... but its more secure for critical data ;)

[@timytimotius4679]

And faster too

[@leexgx]

RAID10 doesn't use parity so it's technically less secure then RAID6 (RAID10 is for some redundancy + speed)

[@Baldroega]

@@leexgx are you serious? Raid 10 is stripping+ mirroring so it is more secure and more fast, of course at expense of more disks and less space, it what's it is used in critical infrastrutures... trust me ... it's my work loool

[@dancoulson6579]

Holy Shit!! Did not realize this could happen. I thought a URE would result in one file or directory being lost, not the entire lot... I am actually using 6x 2TB disks in raid 5 on my server right now, and have been for a few years. Thank god I've not yet had a drive fail. I will be changing to raid 6 ASAP now. This video has probably saved me a lot of hassle in the future.

[@dancoulson6579]

+Dan Coulson Found out my raid controller does (perc 5/I) does not support raid 6. I think raid 10 will be the next best option. I'll still get half the space ~5tb after formatting) Much more reliable too.

[@ThePogiako12]

trust issues.

[@maxheadrom3088]

I use RAID 5 with 3TB disks. Once I needed to rebuild once and it worked! The HDDs I use are regular 3.5 5,400 RPM disks. I found your video looking an answer to the question: "what is safer: two 5 disk RAID 5 or one 10 disk RAID 6?". There's a probability of a drive failing and one can calculate chances two drives fail. BTW, if you're using RAID, chek the SMART often.

[@1creeperbomb]

Wait wait, is this his joke channel or his real one lol?

[@jejjju]

I am not fully convinced by you. If errors are so rare, then when doing recovery in RAID 5, after one disc goes dead - we would loose maybe few files, and it doesn't mean that whole recovery would go wrong. Right?? (In RAID 1, after we lose one disc, the second one also may have some errors, and it doesn't mean that the whole recovery wouldnt work...) My concern about RAID 5 is: maybe you're right, if the discs are encrypted? Could you please refer to this message ThioJoeTech?? Perhaps I misunderstood your video, sorry :(

[@christophesch4070]

That is why we use Raid 5 and 6, but need to have a Backup. I see your point. But I cannot see your conclusion. RAID and backup are not the same thing

[@GuillermoFrontera]

Agree, no need for 3 parity drives. you need RAID 5 if you use something like 3 to 5 disks, or Raid 6 if you are using 5 to 32 disks AND your Backup.

[@jordanbanko5347]

Christoph Esch then what do you use as a backup?

[@ryanmarx7370]

@@jordanbanko5347 I'd go Raid 5 and look into Crashplan. for $10 a month it backs up what folders you ask it to with unlimited space. Easy to restore from and keeps file versions so you can go back to a file version from last week if you want to.

[@housewares]

I think for a bunch of mystery-meat disks you found lying around in the storage closet, yeah, use RAID 6. But if you're not fucking around and actually trying to run a business: use one big RAID 10 combined with a real backup regimen...

[@rodrigofilho1996]

Just use 6 drives in raid 0 for maximum craziness :) :) :), I live dangerously...

[@markjansen1083]

A lot of newer harddrives like the ironwolf pro have one URE in 10^15 bits instead of 10^14. So that means 125 tb of storage where one bit will fail you.

[@ThioJoe]

RAIDs? Isn't that something you do in video games?

[@philcrum2566]

lmao

[@YorgeZay]

+ThioJoe I thought RAIDs was an std

[@azaddilek1693]

Yes u raid in minecraft factions

[@penwoopydo]

I THOUGHT RAID WAS A BUG REPELLANT!!

[@tomthetominatorftw4106]

Actually RAIDS is the same thing as aids, but you get it from rape, that's what the "R" is for. Don't trust this guy's channel, ThioJoe will make a video explaining it.

[@barneybarney3982]

personaly i know about a risk of loosing data from RAID5 during rebuild cuz drives are 100% loaded ( work+raid rebuilding) and have bigger chance to fail at this time, so basicly you can loose data on RAID5 during rebuild process, hard to tell if its cuz of URE or cuz something else, but RAID5 is ok basicly to 4-5 drives max, everything above is for RAID6 or if you can afford it, i belive none on common users cant( and dont even need it :D) then something like RAID60 or w/e

[@ImastMadafaca]

Is RAID 10 faster than RAID 5 and 6?

[@marciocattini12]

yes raid 10 is actually 2 raid 1 in raid 0... it's actually 1+0

[@skaltura]

HW RAID10 -> No. Linux software RAID10 -> Yes and No. RAID5 achieves 95% bare hardware read speed. RAID6 a fraction of that. RAID5 and RAID6 takes a tremendous hit on write speed. Much more so on RAID6. RAID6 is not worth it. RAID5 for upto say 6 drives, further than that RAID50. Much higher performance, same level of redundancy. RAID != Backup.

[@DatamedicsRecovery]

That depends on your RAID controller card. My Areca cards that I use can run RAID 6 at nearly the same speed as they can run RAID 5. I've tested it, and with 8 drives it can read/write at ~750Mb/s in RAID 6. Cheap RAID controllers, however, won't be able to do that. The drives independently will only do around 130Mb/s, so it's losing very little to overhead if you figure that 6 drives (not counting parity) X 130 = 780Mb/s (max hardware speed) and I'm getting 750.

[@HappyBeezerStudios]

130 Mb/s sounds quite slow. My drives do around 120 MiB/s Thats around 8.3 times as fast. I would check your drives.

[@justinstar9710]

very good explanation, though I think mentioning the re-build time delta of RAID5 and RAID6 is worth it. Plus, RAID6 is required much more sophisticated RAID controller, so pure software RAID controller very likely isnt going to cut it.

[@scottscott5827]

Never use RAID5. If you are an IT tech chances are you will: 1. Get a call at some point in time to go deal with a RAID5 disaster 2. Never get a call about a RAID1 or RAID10 disaster

[@rollotomassi4768]

I always use Raid 10. Raid 5 rebuild is complicated. I've seen where it never finishes rebuilding. Raid 10 rebuilds usually finish in a couple hours. I know R10 is pricey, but it is 100% worth it. FYI, Setup some monitoring of your servers as well so you don't have multiple hard drive failures before noticing.

[@alexrox321]

Do you ever blink?

[@GizmoFromPizmo]

Unrecoverable Read Errors (UREs) are rare unless you're using Seagate drives. I'll very buy Seagate drives again. UREs is what killed my last RAID 5 array. One disk went bad but I could not rebuild because the other Seagate disks all had UREs on them.

[@TheGeekPub]

N A S

[@davebing11]

and its compounded in that ALL of the drives have EVERY sector read during a rebuild for maximum heat and least reliability. With 8 * 18TB your talking about 24 hours non-stop to rebuild

[@mustafa.h.k]

i thought this guy is a troll what happen to him?

[@grumpyhale821]

Mustafa Hashem he does troll.

[@benpoe4335]

I think it's a great explanation. I've handed out tissues to folks who bragged about their screaming RAID (striped) and they didn't know that one bad drive killed everything. In the last few years ....RAID controllers can employ 5 or 6 and so there's no difference in the cost.

[@TheN4y0]

I know this video is a million years old in KZbin years but there is one downside to raid 6, but you have to have minimum 4 drives to do that. Shout out to anyone watching this video in 2020

[@JLMtime]

I was setting up raids before you were born but you were clear decisive & I actually learned something about RAID 6 vs 5 from you nice brother !

[@JLMtime]

With power failures (biggest issue for me) I have found that raid 5 with medium size SSDs RAID 5 is fine I always figured raid 50 would be the best before 6 what are your thoughts ?

[@AllMyHobbies]

your out to lunch!!! you don't know what your talking about!

[@Snubbs]

those diagrams were super useful! i had no idea how parity stripes worked even after reading extensively until i had a bit of a look at those pictures.

[@daltonrandall4348]

Everything I have read says that even RAID 6 is asking for trouble - if you care about your files, you should use RAID 10.

[@mnemonic_de]

This guy is right. A couple of years ago I nearly lost data because for whatever reason one drive died and the other had lots of errors. ZFS told me exactly which files were unrecoverable and thank god I had a backup for them. The backup was old so if other files were affected they might not have been in the backup and therefore then been lost. After fixing the RAIDZ I migrated to RAIDZ2 which is equivalent to RAID6. Additionally I copy the really important files daily to a backupdrive using snapshots and replication. Additionally i advise only to use drives that are made for NAS. They feature TLER (time limited error recovery) which is very important in a RAID in error situations. When I had the error mentioned above I didn't have these drives because they were only available for enterprises and extremely expensive. With upcoming of home-NAS to the mass market this changed. So avoid desktop drives for NAS.

[@kamalb008]

Hey Joe, lets us consider the following scenario. what is I have 10x8TB array of disks configured with RAID6. So even if two disks fails( Since RAID6 ). I will be having 64TB of data to be scanned for recovering the last drives. So from your URE probability calculation, there is URE happening. Then RAID6 is also not useful. What would you suggest about this... !!!! Thanks in advance

[@elim9054]

The math isn't quite that simple, because URE probabilities are independent from disk to disk. Reading 64TB across disks that each have a URE rate of 1 in 10^14 does not guarantee that a URE will happen, because a URE not happening on one disk has no bearing on whether or not a URE happens on another disk. It'd be like thinking that rolling a 6-sided die six times guarantees that you will roll a specific number at least once. You'll get _more chances_ to roll a specific number, but failing to roll that number will never make it more likely that you will succeed to roll that number in the future. All of that said, adding more drives to an array will always statistically increase the likelihood of a failure by a little bit, unless you're using RAID 1 where more drives always means more fault tolerance. And 10 drives is quite large for a RAID 6 array. You should definitely have regularly scheduled backups if you don't already. Off-site is best if it's feasible, but any backup at all is better than nothing.

[@markp2085]

Of course backups are a must unless you enjoy playing Russian roulette. As a former network administrator, over 20 years, we had 4 drive failures in a raid 5 setup. Luckily, we never had a problem with an URE. But if we had, are drives were backed up to tape drive and other hard drives. URE's are probably rare, but when they happen, it can be disastrous. Will the average home user have a failed drive in their raid 5 and a URE? Probably not, but is it worth taking the chance over.

[@alfredsmith6039]

In 16 years I've had two disk failures in RAID5 on two NAS's. Both recovered without any drama whatsover. You should also renew the disks every 5-6 years. Plus S.M.A.R.T. will warn you of impending issues.RAID5 was never intended as a data backup so I don't understand the criticism.

[@KeksBln]

This is what happened to me. I had a Synology DS412+ with four WD Red 3TB. One fails and I replaced it immediately. The RAID rebuild took a few days. But DURING the rebuild another disk failed -- fortunately the volume was still readable (but not writable anymore; i.e. read-only), so I could copy all data to my new DS1813+, which I ordered a few weeks ago (including WD Red 6TB disks), but hadn't setup. After setup the new DiskStation I could copy all data to it. When setting up, I used RAID6 (SHR2). ;-) This was 2014 and I am using this NAS until today with no further heart attach. 😆

[@uzefulvideos3440]

That's why I use Ultracopier with "verify checksums" activated. I use a small NAS with 2 8TB drives in RAID 1.

[@Tivis7]

I too was gonna say, ppffft I don't have the money to be wasting storage on THAT much redundancy. But after learning about the 12tb issue I realized I'd be cooked in a drive failure scenario since I plan to use 5 renewed 20tb NAS drives 😳(seagate Ironwolf Pro) my small business is not exactly swimming in money yet. Thanks for the info, 60tb is still better than 80 corrupted Terabytes!

[@chromerims]

Great information. Very useful video 👍. In the future, I will look for (quoting you): "Non-recoverable read errors rate", "Error Rate (non-recoverable)", "Unrecoverable Bit Error Rate (UBER)", or something similar, probably listed along with the 'reliability' specs in the data sheet. Rated at 1e15

[@Yemto]

I used raid 0 to install my steam and origin games on, since saves aren't usually stored in the install directory, and I have no data cap. it wouldn't be a big issue if the raid failed, and it's a lot cheaper than buying a SSD big enough

[@scottdotson2243]

Yemto What is the best way to setup your system with say 100 tries with 15 external tide together with sub 3.0 hub?

[@mannygee005]

where do you buy a RAID 6 system? So 8 years later a RAID 5 is available anywhere. It can do RAID 1, 5, 10 in the same box but never 6. Have times changed?

[@tomwells8093]

Drives almost never fail where you can't do anything with them. 99% of the time its a slow death where data is still recoverable. When a drive has issues I would recommend taking it out of the array and copying data over to another disk in case. Then rebuilding the array

[@daisyduck8593]

I found a new calculator for Raid 1/5/6/10: "RAID Reliability Calculator" on wintelguy com. You can calculate the "Probability of read error during rebuild". For an example the rebuild success for a Raid 10 of 4x Seagate Exos 16 TB is minimum 87% (1,00-0,13= 0,87).

[@xupan1221]

You are saying, if I flip a coin and each time I would have a 50% of getting tails, then after 2 flip I WILL GET TAILS. That is not how probability works... after reading 12TB of data, the chance for the next bit to experience URE is still one in 10^12 chances, not jumps to 100%.

[@daisyduck8593]

Google it: The "RAID rebuild failure chance calculator" is a big help !

[@daisyduck8593]

For example: Seagate 8TB Barracuda hard drives data sheet says (maximum) 1 per 10e15 nonrecoverable read error per bit. That means on a RAID 5 with 5x 8TB with the calculator is a (minimum) 77% chance of rebuild succes ! But if you are unlucky you are the 23% of cases...

[@theodorstravels]

Is all the data really lost though, with the read error? Wouldn't you have like one or two corrupt files, but still get the rest back?

[@squirtmph]

Could you change raid setting with data enclosed any Time you want, with out any data risk lost? Thanks

[@gund89123]

RAID 5 with good back up strategy is better than focusing too much on RAID.

[@micerr]

One should be backing up their data regardless of what RAID configuration you are using. Yes, RAID 5 is riskier than RAID 6. That risk may or may not be acceptable depending on your situation though.

[@BrianThomas]

I know this was a few years ago, but correct me if I'm wrong. This really depends on the number of drives that you have? Right? What if I'm only using 4 drives instead of 7? This will certainly change my chances a bit. I agree with what's said, but the scenario certainly depends on a few factors.

[@bobbymoss6160]

The best backup plan is to have 2 identical NAS using HDD from 2 different companies.