On 3/7/08, Scott Silva ssilva@sgvwater.com wrote:
on 3-6-2008 3:58 PM Scott R. Ehrlich spake the following:
So I've learned a valuable RAID 0 lesson, and it fortunately was not a major catastrophy. I got lucky, and had a workable-enough backup on tape to make the user who needed some data happy.
Now, from the OS side, LVM is an option. Say the RAID controller only allows hardware striping or mirroring for logical volumes, but I want to use more than two disks, and I don't want the RAID 0 problem again.
When I get a replacement disk and build the system from the ground up again, I could, conceivably, use hardware RAID 1 for the OS on two disks, and CentOS 5 64-bit's LVM for software RAID 5 (or maybe 1+0 if available) on the remaining for 4 disks, maybe 3 disks as active and the 4th as a hot spare?
Hi there,
Minor point:
Rather than go for a RAID 5 with a hot spare you are better off going for a RAID 6 array using the 4 discs if your hardware supports it.
If your RAID 5 has a disk failure then has another whilst it is rebuilding using the hot spare then your data is b0rked whereas with RAID 6 you can tolerate 2 disk failures and still access the data.
You lose the same amount of capacity that you would have with the RAID 5 + hot spare set up that you are considering.
mike