Michael Simpson wrote: > On 3/7/08, Scott Silva <ssilva at 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. > > 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