RAID - CompTIA A+ 220-1001 - 3.4

[@wallysworld8380]

Currently in school for IT specialist and currently studying about A+ in class and Professor Messer has been that extra help in helping me understand the E Book a little bit more clearer. Thank you so much!

[@ethanlewis2313]

What was the A+ certification exam like?

[@flameofarnor2021]

Thank you for this! RAID was one of the things that I kept hearing mentioned at my work and wasn't sure what it was about. This was super helpful!

[@shoreehastad7441]

I've watched this course multiple times and watched the study groups (not live). For the first time on one of your videos I forgot to turn on 2x speed... you sound much different than I thought. Anyways, great videos. Hopefully with this help I can start to make money and enjoy my life in the future.

[@kevinmichael4898]

Thank you Professor Messer! I failed the test with a 596 last time and need to get it done this time around. Thanks for all the teaching! 🙏👍

[@user-ns4uu3vv2i]

howd you do bro

[@HenryThe12]

This video helped a lot! I was familiar with RAID as a term but I wasn’t quite sure what it was exactly. I now know that it’s not for backup and it’s more for file integrity. Thanks a lot, Professor!

[@Brovioli]

This video reminded me that my Hard Drive is about 5 Years old now.... Currently making a backup while studying! Thanks Professor Messer! You helped me take out 2 birds with one stone haha!

[@BichaelStevens]

That's nothing

[@jasgarcha4783]

Great content, delivered in easy to understand format.

[@Shayanzass]

Wow this explained it so easily compared to the book. It's so much more simpler than I thought.

[@Alziax]

For RAID 5, by "parity calculation may affect performance", does that mean it'll affect performance when it's reconstructing data, or for every single read/write?

[@professormesser]

Since there's missing data (a whole drive of it), it would have an impact on both reads and writes.

[@TriplBBB2023]

@@professormesser I think Alz means "does Parity generation affect every single read and write or does it only slow down when it is recreating data from a lost drive"

[@Brovioli]

Everytime Read/Write because it has to take time to write out those Parity And even Worse during a drive Crash cause its taking time to ReWrite/ReConstruct those. At least i would assume that, Anyone feel free to correct me if i am wrong.

[@remetremet]

Basically it's not an issue anymore - CPU power of computers and servers is huge today (and last 10 years at least) so XOR operations can be done really fast. The only problem now is that drives grew in size up to 20TB each, so reconstruction on these large arrays can take days. Basic read and write operations are fast enough though. And even when you use 2 or 3 parities (RAID 6, RAID Z3), the performance is quite ok. Anyway today is different situation with HW/SW RAIDs too - SW on CPU is much more powerful than these cards with all that dedicated chips (FPGA), so the solution today is better to use HBA as physical connection to backplanes and drives and SW (more like OS-integrated) RAID solutions like ZFS, BTRFS, etc.

[@johnfernald-t9y]

Maybe a dumb question, but are there any scenarios in which RAID drives would not be hot swappable? For example, with RAID 0, is there a potential that swapping out a drive while the system is running would result in an incomplete "stripe", therefore rendering the drive array useless?

[@professormesser]

A hot swappable drive means that you can remove and insert the drive while the system is powered. Hot swappable does not mean that you can unplug a drive while the system is writing data and expect the system to remain operational.

[@johnfernald-t9y]

@@professormesser Thank you! Very much appreciated.

[@AblewellVSAllan]

Just to Clarify, for Raid 10 or(1+0) if i have two Hard Drives that are Corrupted or broken, i will not be able to recover it due to no Parity. Where as If i lose 1 Hard Drive i am still able to Recover ,because of Mirroring?

[@codywalker9356]

correct

[@codywalker9356]

if two hard drives fail, you will not be able to recover the pieces of data that were stored on them which means your file as a whole would be corrupt as there would be missing pieces of data due to the failed drives. If one drive fails then the data can still be saved as it has been mirrored on to an extra drive as a backup.

[@XoraNedd]

If one of the drives in Raid 0 fails, is it possible replace the drive and restore from a backup as a means of recovering the array? or would you replace the failed drive and build back the array?

[@professormesser]

There's no redundancy with RAID 0. If you lose a drive, you have to replace the drive and restore from a backup. There's not enough data left on the remaining drives to rebuild the data.

[@remetremet]

If you have a backup than you can restore your data. Otherwise if you lose any drive in RAID 0, you're done.

[@NachosXD13]

Maybe I'm missing something, but pertaining to RAID 5, if Disk 0 was to be broken, would I be able to recreate or restore the Parity D block? And what effect does that have on the three other D blocks (1D, 2D, 3D)?

[@professormesser]

If any single RAID 5 drive fails, lost data can be rebuilt based on the parity information. If the parity information of a block series is lost, then nothing needs to be rebuilt.

[@TriplBBB2023]

Parity D signifies all the data of 1D, 2D and 3D I think. Or perhaps I've misunderstood?

[@frontend8804]

When you use the term "Drives" are you referencing the Disks in the video as being the drives?

[@professormesser]

Yes, the drive is referring to a hard disk drive or a physical storage drive.

[@frontend8804]

@@professormesser Thank you. Also I have recently (October '19)security + SY0-501 and there aren't many entry level roles that require that. I'm considering going for A+, In your professional opinion, is it worth it to do so?

[@lucasmills1246]

@@frontend8804 It's very worth it, just beware because certain employers are angry with CompTIA right now. They may view your A+ as useless, and that's really only because of the issues people have with CompTIA.. Apparently they've been doing some shady stuff.... I'd still go for it though.

[@WhiteZorin]

Hi @Lucas that's interesting, could you tell a bit more about this situation? I am preparing myself for A+. What kind of shady stuff, can you point to anything? I will google anyways, after studying session ;)

[@lucasmills1246]

@@WhiteZorin they were lobbying against right to repair, which goes against the whole principle of being in the IT field. We should have the right to fix all our own hardware, even if it is made by Apple.

[@marcindziewiecki7097]

In case when we are using software- based RAID. What happen if we lost disk with operation system or software we are using for raid? Is it possible to read raid disks with other system/software on new disk?

[@professormesser]

If you lost a disk that contains your operating system and it's not part of a redundant array, then you'll need to replace the drive and restore from a backup. Remember, RAID isn't a backup strategy.

[@Mustlehard]

@@professormesser if it’s not a backup strategy then what’s the point I was totally getting it until I read this

[@professormesser]

@@Mustlehard The point of RAID is to keep the system running if a drive fails. If you overwrite or delete the data yourself, RAID can't help you.

[@remetremet]

@@Mustlehard RAID is about availability - when you have a server, you want to have no downtime. So when one drive dies, RAID makes you server working, you will replace drive (or use a hot-spare) and you had no downtime. Backuping is total different job. You can somehow count it into your backup strategy - like you have two online storages in two different locations both with RAID 6, plus LTO automated tape library, plus let's say older encrypted data storing into Amazon Glacier service. This is backup, you have two online copies with some redundancy and quick access, you have offline copy and have offline archived copy. But RAID itself is not a backup solution.

[@mknight7209]

which is the best and most cost effective one? 10?

[@luqcya9877]

in term of efficiency10 but in term of budget i say 1 should be good, just my opinion

[@johnsmith8981]

Depends if you care about speed or redundancy.

[@remetremet]

It depends on how many drives you have, but there are formulas to find it out. Let's say RAID 1 - you need 2+ drives for capacity of one or you will lost at least 50% of capacity or you have to spend at least 200% on drives. RAID 5 - you need N+1 drives for capacity of N drives. RAID 6 - you need N+2 drives for capacity of N drives. RAID Z3 - you need N+3 drives for capacity of N drives. RAID 10 - you need 4 drives for capacity of 2 drives, so this is same as RAID 1 from this point of view. Unfortunatelly there is more limitations on many drives you can have with these RAIDS 5,6,... Typically it's like 8 in one array (and you can have multiple arrays). These limitations is much more important with today drive sizes of 10TB+. For example when you try to create RAID5 from 32 14TB drives, statistically one parity drive for 32 drives is not enough and in case of reconstructions it will be so long so another drive can fail. And than you're doomed.

[@elmen995]

So is RAID (not RAID 0) a form of backing up data?

[@professormesser]

RAID is not backup.

[@8088bit]

another way to think about it is this RAID is a way of improving data integrity and performance. it is not backup because the data itself can still be corrupted by viruses, evil intent, ect. for it to be true backup the data needs to be copied to an external data storage method, ie another computer, CDs, tape, so that it can no longer be altered. RAID however provided data integrity for that system, primary to prevent loss of data as the system components age and are used, corruption of bits that might make a file unreadable for example. RAID 0 however doesn't provide this data integrity it provides performance improvement for the writing and reading of data. you have n number of disks in your RAID 0 setup and can write to them at the highest shared common speed (n* write speed = newer faster write speed) an example of this in use would be if you had a gaming pc and used a RAID 0 setup to improve your loading times for games

[@elmen995]

@@8088bit thanks for the info! It makes more sense now. I didn't really think about malware and other forms of corruption.

[@dubgreens123]

@@8088bit thanks for this reply. I couldn't think of any practical applications for RAID 0, but it makes sense that it would cut down load times, even if it is unreliable long-term due to the lack of redundancy

[@aliceknight9830]

@Professor Messer - I've recently bought your practice exams and was wondering if you have a rough guide to marking yourself on the PBQ's in terms of percentage? I know compTIA don't release specifics for their marking scheme, but I'm pretty sure they've mentioned giving you x amount of marks for however many steps you perform successfully? Just as an example the only part I got wrong on your 1001 A+ PBQ (B1) was the channel, but everything else I did correctly.

[@davidqatan]

On the compTIA website, their practice test gave me 1 pt for each correct step I performed.

[@notmyregret]

Hey Professor, I was wondering... Is RAID 6 something to look forward to? Or do they just consider it similar to RAID 5 and not needed to look at?

[@professormesser]

RAID 6 is not part of the CompTIA exam objectives.

[@iamtylerman]

this video is sponsored by RAID.... 10