What Raid Level? 6 or 50?

[FN-GM]

Hi,

 

I have a SAN here that is on Raid 10 at the moment. Its used for the Virtual farm and that hosts most of our servers. But its using up loads of disk space that I need. I am looking to change it to either raid 6 or 50. What would you do and why?

 

Thanks

[foofighterjim]

Available space should not be the deciding factor in this decision, if this is your only consideration for change you may want to look at adding to or replacing your SAN (easier said than done, I know). With either option you listed you will take a disk write performance hit moving from 10. I would have a slight preference for 50 as I always feel that 6 causes too much of an overhead on the hardware.

[Bobby_Tables]

Available space should not be the deciding factor in this decision, if this is your only consideration for change you may want to look at adding to or replacing your SAN (easier said than done, I know). With either option you listed you will take a disk write performance hit moving from 10. ...

Completely agree.

Performance wise, 50 would be better than 6, but it's bad in terms of fault tolerance (only takes one of the two RAID-5's to fail). RAID 10 would be preferable to both.

 

What is your hardware? Could you look at upgrading the drives or adding more drives?

Edited November 26, 2014 by Bobby_Tables

[PotNoodleTech]

Raid 10 is ideal but obviously comes at great cost to capacity.

 

Used Raid50 here instead of Raid 6 to leverage write performance. After performance testing ended up with 5 x groups of 3 x drives in the raid 50 array + 1 hotspare.

 

It's been very reliable. The great thing about doing it this way is because each raid 5 group only has 3 disks, the rebuild speed if you lose a disk is very fast and the global hotspare automatically takes over. IN our case the hot spare fails over within a few hours, part mitigating the chance of data loss due to a second drive in the same array failing. The chances of two drives failing both in the same array are fairly low.

 

You're mileage may vary though!