Prebuilt NAS and RAID with 4 TB hdds

[beginner99]

With 4 TB drives RAID 5 and probably also RAID 6 become pretty much useless.

http://storagegaga.com/4tb-disks-the-end-of-raid/
http://www.zdnet.com/has-raid5-stopped-working-7000019939/

Reason being that it's almost guaranteed you can't rebuild a RAID5 especially with 4 TB discs. But even 2 TB discs are problematic.

I'm thinking about getting a NAS but with 4 TB drives I could just get a 2 drive NAS and run the drives as individual drives. If one fails, just reload data from backup. Note that if the backup has data corruption that won't prevent the data from being reloaded or only the corrupted file is lost.

How do you guys handle this? Do you use RAID5/6? What are the experiences? Did you ever have to rebuild (with 2TB+ drives) and did it work?

 

[nk215]

Hi

What's problematic about 2TB RAID5. That's what I have 5-2TB RAID5 setup. It has been running fine.

 

[dave_the_nerd]

ZFS RAIDZ is supposed to work around this. But frankly, with 10GbE, it's probably faster to initialize a new array and restore from backups.

If you have backups. Muhwahahahah.

Hi

What's problematic about 2TB RAID5. That's what I have 5-2TB RAID5 setup. It has been running fine.

Read the articles he linked. If you don't understand them (no shame in that, a proper explanation of the problem is a bit technical), just know that if one of your drives fail, there is a non-zero chance that the RAID rebuild will fail miserably and hose your array. The bigger the drive, the higher the probability, because reasons.

 

[Railgun]

That's a big maybe.

 

[dave_the_nerd]

That's a big maybe.

Keeps life interesting.

 

[rsutoratosu]

I been on 4x4tb raid 5 for over 2 years now, using the hitachi drives. So far no problems. I do have the data split into 2 other server that us 8tb each.

haven't ran a tape backup in a while but looks like i should

 

[dave_the_nerd]

I been on 4x4tb raid 5 for over 2 years now, using the hitachi drives. So far no problems. I do have the data split into 2 other server that us 8tb each.

haven't ran a tape backup in a while but looks like i should

The problem doesn't happen until you do a RAID rebuild on a new drive.

 

[rsutoratosu]

nothing like a real world test.. ill make sure my junk is backed up and pull a drive to test..

 

[nk215]

I don't treat my RAID5 array as a backup. It's a way to have more uptime. Basically, I don't plan on rebuilding. I plan on buying time while getting my backup up and running.

If something goes south, I'll keep the array running at slow speed and while getting another one up and running from the backup. I have an entire redundancy server but I'll have to get to it and manually switch it on (1 hr max).

I actually went in a read the link and I don't quite agree with it.

Basically, the link said, if your HD fail in a large RAID5, the chance that you'll encounter URE while rebuilding is also certain - in a large array - which results in data lost.

That statement I agree with.

However the article went on and said that so RAID5 does not provide more protection than a single drive.

That statement I disagree with. Because in a RAID5 if you get URE you can recover. In a single HD, if you get URE that data is lost.