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

[@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.

[@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

[@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.

[@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.

[@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.

[@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.

[@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.

[@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.

[@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.

[@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

[@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

[@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.

[@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

[@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.

[@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 :)

[@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.

[@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.

[@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.)

[@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.

[@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

[@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

[@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.

[@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. :)

[@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.

[@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.

[@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.

[@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.

[@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?

[@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

[@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

[@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.

[@Straatbrak]

Ok so I can use RAID 5. Thanks

[@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

[@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.

[@Sherwin724]

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

[@oofig]

HAHA U GET REDDIT WOOSH

[@moreseun]

lol

[@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.

[@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

[@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)?

[@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?

[@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. 😉 )

[@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.

[@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.

[@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.

[@seanmikhaels]

There’s a solution for the URE , just run a scrub job every week or so and that should reduce the chances of corruption

[@BuschFrankmann]

Like every manufacturer is doing automatically in background. :)

[@eddeig]

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

[@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.

[@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.

[@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.

[@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.

[@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.

[@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

[@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.

[@ThePogiako12]

trust issues.

[@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?

[@rodrigofilho1996]

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

[@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.

[@alexrox321]

Do you ever blink?

[@scottishphotography9680]

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

[@Halawany]

What's wrong with raid one 🤷🏻‍♂️

[@bertramusb8162]

Usable space cost

[@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.

[@daisyduck8593]

You calculate with cases of error rates of maximum 10^14 but seagate's hdds (last 5 years) all have error rates of maximum 10^15, what makes risks much lower. Use the raid RAID rebuild failure chance calculator to see chance of your Raid setup.

[@davebing11]

thats enterprise grade. consumer grade is still 1*10^14

[@daisyduck8593]

@@davebing11 No dude. Cheap barracudas have since many years a max failure rate of 10^15. Check spec papers ...

[@davebing11]

Seagate ironwolf IS an enterprise EXOS hardware with different SW optimization

[@daisyduck8593]

@@davebing11 can't you read ? I was talking about the most cheapest you can buy, the barracuda harddrives. And even the ironwolf and exos everybody can affort them... so 10^15 is for everyone exept the 2,5 inch barracudas, they still have 10^14. But even for 10^15 the chances for a rebuild fail are still risky for raids over 32 TB...

[@daisyduck8593]

But i also have to say barracudas are designt to use as a single drive. They don't have vibration sensors. It is more safe to use ironwolf or exos for raid systems... As far as i know dell says up to 5+ drives in a raid you need vs. But i say up to 1+ you should use vs...

[@Earlzo2325]

excellent content from the Michael Cera of Tech :D

[@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 :(

[@1creeperbomb]

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

[@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

[@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!!!

[@mustafa.h.k]

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

[@grumpyhale821]

Mustafa Hashem he does troll.

[@maxmustermann194]

RAID6 starts to play out it's real strength in larger arrays of 5 drives and above. Very good usable storage scaling with 2 drive redundancy.

[@TheGeekPub]

N A S

[@jaycie5021]

My raid is my backup. The odds of losing data on my primary computer or the entire drive and a drive on the raid and having a ure at the same time is low enough not to worry about.

[@AllMyHobbies]

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

[@jwinslow5661]

I agree with the choice of using RAID6 over RAID5 for all of the reasons that you mentioned.. One thing I feel you may have missed is that when a drive fails, the other drives take on more work especially during a rebuild process. This strongly supports your decision to recommend RAID6.

[@peteradshead2383]

I can see your point of having the extra party disk due to the extra stress of rebuilding the volume on each of the disks and the possibility of a second drive total failure. … BUT … Let’s repeat what he said in this video “you will come across a read error and it will fail to rebuild and you have lost everything” From what was said it sounds like that if you get one unrecoverable error the entire volume will not rebuild because every byte is need for the party ( like a zip/rar file ), doesn`t Raid 5 rebuild using blocks , so a faulty block will not mean a lost everything like any bad block situation only a full disk failure. What I`m saying the idea may be right, but the reason for it is totally wrong !!!!

[@leebromley1411]

I had a RAID5 array, and 1 disk in the array went faulty after over 40000 powered on hours, I managed to rebuid the array, however over the space of 6 months the other drives failed leaving just the new drives in their place. I believe rebuilding the array does stress the other drives in the array to the point of failure, especially if the drives were brought together and installed together. As I said the first failure was at just over 40000 hours on a 4tb WD Red. The following failures were at 41200 hours, 42900 hours , 44300 hours. In the end I brought an extra disk to add to the existing 4 and built a RAID 6 array on 5 disks after backing up my data and starting from scratch. At least now I have 5 disks brought at differing times over a space of 8 months, hopefully forthcoming failures will be spread out.

[@HappyBeezerStudios]

I'd evcen recommend to have the drives with different run hours. If one particular drive has failed, how good are the chances that none of the other identical drives will go down shortly after. Ohj, and even the rar format allows for recovery parts not unlike a parity checksum on RAID 5/ 6

[@falcon81701]

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

[@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. 😆

[@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.

[@kahelsoro]

Post 1987: RAID = Redundant Array of Independent Disk Pre 1987: RAID = Redundant Array of Inexpensive Disk

[@SeaJay_Oceans]

Most people using RAID 5 at home are using only 3 or 4 drives, and it works just fine.If you want fast performance, you can use a 2 level cache like Romex PrimoCache.PrimoCache is for speed, using your extra RAM for read/write caching, caching all your commonly used files to SSD, and effectively turning your HD into online cold storage. The RAM caching greatly reduces wear on your hard drive, and extends the life of the SSD your using as the 2nd level cache.The most important thin, is to replace your hard drives just like car tires. Before the 3 year or 5 year warranty is up, swap out the your old drives for brand new ones. Most people replace PCs every 3 or 4 years anyway, so you probably are due for a new system after 5 years anyway...

[@uzefulvideos3440]

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

[@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 ?

[@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.

[@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...

[@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.

[@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.

[@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 ?

[@Mark-nl1up]

I've used RAID 5 on my symbology media server for 9 years with WD black drives not one failure. Dumped those drives and moved to WD Ref had my first failure swiped the drive out and was fine. Never looked back.

[@elijahhmarshall]

I've read all over that read speed is fast on RAID5 and RAID6, but due to the need to write parity data across all drives, the write speed is very slow, even with certain hardware RAID Controllers

[@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...

[@JevoKitano]

I just had a disk fail in a 4-drive RAID5. Swapped the drive and it automatically rebuilt it - no problem at all. Been using RAID5 for many years and can recommend it. RAID6 would only make sense with 5drives+ dude.

[@zeppast]

The problem with raid is it doesn't protect against user error or file corruption it's not really a viable backup solution.

[@rollotomassi4768]

That's why you run your OS on a separate drive/raid array

[@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!

[@daisyduck8593]

Dell says RAID 5 (with over 1TB drives) is not good anymore for buisness and critical data.

[@daisyduck8593]

What is strange because the RAID rebuild failure chance calculator caculates a Errorless rebuild success chance of minimum 98% at 3x 1TB in Raid 5 and today's standard hdd error rates of maximum 10^15. So minimum 98% is not save DELL ?

[@peterdavies4122]

Hi from 2019 - what do you think is the new standard now Joe?

[@greky4012]

Hi, that's right in theory. Regarding your reason, it would also make no sense to build RAID 0, RAID 1 oder RAID 10. Because all of it would not be safe enough.... at least in theory. But in practice, good array controllers do in small intervals surface scans and analysis so you don't have to worry about URE. And by the way, RAID 1 does typically not increase read performance! Cheers

[@aero1ret]

Selection of RAID type prolly should depend on the size of the array. An 8 disk array with R6 will lose 1/4 of the disks for redundency. But with a 4 disk array R6 will use half the disks even tho the the odds of failure are halved. I have no familiarity with very large arrays but I'm sure they have specific design requirements. w3

[@ZigUncut]

Yeah with a four disk array (like a qnap nas) then you might as well use raid 10 which will be faster both in usage and rebuilds.

[@l3p3]

I use BTRFS on top of my RAID 5, so an invalid bit can get detected. When there is a read error, it will be just a single bit flipped out of some terabytes. And as I said, that bit will not be a big problem since BTRFS uses cluster checksums and can repair an invalid bit.

[@l3p3]

And if not, it is just a single bit. I do not care.

[@jaapaarts1007]

How can 1 parody recover 3 segments

[@ThioJoeTech]

*Parity. Also as I mentioned, triple parity RAID does not exist. You'd need to use a proprietary hard drive array system.