Raid configuration

[beren]

Can anyone tell me why I should have a Raid 1 configuration instead of Raid 1 - 0 (striped) ?

I'll be setting up a Progress v9.1E database on a Windows 2003 server with 2 Xeon 3 Ghz processors, 8 wide-SCSI disks and 2 controllers.

I've had to convince people not to use Raid 5 for database use on several occasions.
Each time however they offer a Raid 1 - 0 setup ?
Is this OK ?

Any suggestions ?

 

[ron]

Without question: RAID 1+0 (mirror then stripe) is the best choice. If you just mirror the discs you want to put DB extents on (RAID 1) then you have to manually place extents, in an attempt to evenly spread the moment-to-moment accessing evenly over the drives. No matter how much you try, you won't achieve it as well as striping.

(Note that RAID 0+1 and RAID 1+0 are quite different. Always choose 1+0 if the option is available.)
I am not a fan of RAID 5. Many prior posts on this site -- and books on the subject -- explain the performance issues with RAID 5. However, so long as the RAID 5 is achieved in the controller, the performance hit is not very much at all, really. But no-one should ever even think about RAID 5 in software ... that will kill you.