RAID 6 vs 50

Danne

Danne

Danne

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Joined
9 Oct 2014
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6
I'm planning on setting up a new array but i cannot decide what raid level i want to run. 6 or 50
The configuration will be 12 2TB drives.
And i'm going to use it as storage for "this and that". so there will not be mutch load exepct when i move files to the array.

What are your recommendations and experiences?
 
Do you mean 50 or 5? With 12 drives you definitely should go for 6.
 
With RAID 50 you are only going to get 10 TB usable space out of your 24 TB of raw disk. That's a pretty expensive use of RAID! With RAID 6 you get 20 TB.
 
I'd go for raid 6 if write performance isnt a huge issue (which it sounds like it's not). It's considered unwise to run raid 5 with anything over 1 TB, rebuild times can leave you very vulnerable to a second drive failure...
 
How are you going to set up the RAID 50? In a previous job we had three banks of drives - that's 3x 19" racks - and RAID 5 was done vertically, and then the disks were striped across. This meant that even if one whole bank failed (e.g. the cable fell out), the data would still be accessible. In your case you'd end up with 16 TB.

With RAID 6 and 12 drives you might want to allocate three drives as parity drives rather than two.
 
Danne said:
Yes i do :)
Use this for example to calculate, https://grijpink.eu/tools/raid/index.php
Click to expand...

Sorry. My assumption was RAID 50 was 5 + 10, not 5 + 0.

6 is better, because you can lose ANY 2 drives and you still haven't lost data. With RAID 50, if you lose 2 drives within the same set, you've lost everything.

Read performance will be the same. Write performance, who knows.

RAID 6 (one array) much simpler than RAID 50 (3 arrays).
 
rotor said:
6 is better, because you can lose ANY 2 drives and you still haven't lost data. With RAID 50, if you lose 2 drives within the same set, you've lost everything.
Click to expand...

Depends how important that redundancy is to him though, statistically speaking if you are going to lose two drives it's more likely they will be in different sets, but the advantage still goes to RAID 6, however IMO the performance advantage of RAID 50 outweighs the possible extra fault tolerance of RAID 6.


rotor said:
RAID 6 (one array) much simpler than RAID 50 (3 arrays).
Click to expand...

Technically it's four arrays because the three RAID 5 arrays are in a RAID 0 array (I know that's worse :P).
 
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ubersonic said:
Depends how important that redundancy is to him though, statistically speaking if you are going to lose two drives it's more likely they will be in different sets, but the advantage still goes to RAID 6, however IMO the performance advantage of RAID 50 outweighs the possible extra fault tolerance of RAID 6.
Click to expand...
There's nothing linking which two disks will die, so there's a 50/50 chance that the 2 disks will be in the same array, in which case bye-bye data.

I honestly don't think RAID 50 will have that much of a performance improvement. 2 RAID calculations still have to take place for each write, just the same as for RAID 6.

ubersonic said:
Technically it's four arrays because the three RAID 5 arrays are in a RAID 0 array (I know that's worse :P).
Click to expand...
I meant 2 x RAID 5 arrays, plus the over-arching RAID 0 array.
 
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