This idea of splitting larger disks into smaller partitions, then re-assembling them seems odd. But it should help with the "bad block kicks out a disk" problem. I have never used RAID0. I have never used more than 1 pv with LVM on Linux. However, if you are going to use LVM anyway, why not allow LVM to assemble the disks? I do that sort of thing all the time with HP-UX. I create stripped mirrors using 4 or more disks. With HP-UX, use the -D option with lvcreate. No idea if Linux and LVM can strip. You are making me think! I hate that! :) Since your 6 RAID5 arrays are on the same 4 disks, striping them will kill performance. The poor heads will be going from 1 end to the other, all the time. You should use LINEAR is you combine them with md. If you use LVM, make sure it does not stripe them. With LVM on HP-UX, the default behavior is to not stripe. Guy -----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of maarten Sent: Thursday, January 06, 2005 9:17 AM To: linux-raid@xxxxxxxxxxxxxxx Subject: Spares and partitioning huge disks Hi I just got my 4 new 250GB disks. I have read someone on this list advocating that it is better to build arrays with smaller volumes, as that decreases the chance of failure, especially failures of two disks in a raid5 configuration. The idea behind it was that since a drive gets kicked when a read-error occurs, the chance is lower that a 40 GB part develops a read error than for the full size 250 GB. Thus, if you have 24 40GB parts, there is no fatal two disk failure when part sda6 and part sdc4 develop a bad sector at the same time. On the other hand, if the (full-size) disk sda1 and sdc1 do fail at the same time, you're in deep shit. I thought it was real insightful, so I would like to try that now. (Thanks to the original poster, I don't recall your name, sorry) Now my two questions regarding this. 1) What is better, make 6 raid5 arrays consisting of all 40GB partitions and group them in a LVM set, or group them in a raid-0 set (if the latter is even possible that is) ? 2) Seen as the 'physical' volumes are now 40 GB, I could add an older 80GB disk partitioned in two 40GB halves, and use those two as hot-spares. However, for that to work you'd have to be able to add the spares to _all_ raid sets, not specific ones, if you understand what I mean. So they would act as 'roaming' spares, and they would get used by the first array that needs a spare (when a failure occurs of course). But... is this possible ? Thanks for any insights! Maarten -- - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
