Michael Simpson wrote:
On 3/7/08, Scott Silva <ssilva@xxxxxxxxxxxx> 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.
sw raid supports raid 6. Another plus for sw raid is that it's hardware
agnostic - doesn't care about controller make, brand, chipset, firmware,
etc.
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
--
Toby Bluhm
Alltech Medical Systems America, Inc.
30825 Aurora Road Suite 100
Solon Ohio 44139
440-424-2240
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