RAID6 is only safe storage >1TB

[zooman]

All,
I wanted to start a thread to see how many people are using RAID 6 in their NAS? I am surprised by how many people are using RAID5 for 1TB+ drives.
The following articles describe how probability starts working against you when you attempt to rebuild a failed RAID5 setup with 1TB+ drives. Currently I only am considering RAID6 solutions because of the risk.

http://blogs.zdnet.com/storage/?p=162
http://blogs.zdnet.com/storage/?p=483&tag=rbxccnbzd1

Any comments, discussions?
ZooMan

 

[Kel]

Thanks for those articles...since I am using raid5 - I now have something else to think about and research... Robin Harris also somewhere suggests the drobopro approach.

Perhaps I need to change my setup to a raid 1 + 0 or multiple raid volume where in my readynas nv+ I can have drive A mirrored by drive b and drive c mirrored by Drive D for my 4 drive nas.

Or take the the "how to back up nas to nas part 1" where Tim H explains his problem and solution for his situation.

Anyway somehow I set things up a while ago and really didn't understand the entire issue

yet another option might be flexraid where each drive in your 4 bay nas is treated seperately and then have each drive resync with other drives somewhere else - pehaps in another 4 bay nas configured the same way ...not sure if this is possible or doable and include cloud backup...

ok this is probably common knowledge for alot of folks on this forum but I just ran across all this tonight.

 

[zooman]

Bummed about Drobo

I looked at the drobo. It has some very appealing features:
- isolation from managing disks (not like raid).
It also has some strong shortcomings:
1) Requires a host computer (I want NAS).
2) Does not support EXT4 FS.
3) separate box required for networking
4) DroboPro is EXPENSIVE! ~$1500

This is not a very good option, though I really like they way they manage the disks. Still looking...
I was considering a QNAP TS-509 with 5 1TB drives as RAID6 giving 3TB storage. But... the issues with RAID, there are TS-509 stability issues I have read about, still need a way to backup this TS-509 for off-site storage.
Also looked at Thecus 5 drive units; they seem to hide info in their 'customer support' blog so that scares me a bit with all the limitations of the QNAP.

Ugg... no great solution yet.

 

[claykin]

Another reason to use Enterprise disks. 10^15 URE means 1 unrecoverable sector every 125TB.

 

[SoftDux-Rudi]

From experience I can tell you that a RAID5 array with such large drives will fail at least 4 out of 6 times when you do a rebuild, especially when you're using the NAS device as well - which in most cases will be true. Rather use RAID6, or RAID 10 (or 1+0) which is faster than RAI10 for reliability

 

[claykin]

From experience I can tell you that a RAID5 array with such large drives will fail at least 4 out of 6 times when you do a rebuild, especially when you're using the NAS device as well - which in most cases will be true. Rather use RAID6, or RAID 10 (or 1+0) which is faster than RAI10 for reliability

Huh? I think you ought to look into problems with your NAS.