On Tuesday 09 February 2010 16:11:14 Stroller wrote: > On 9 Feb 2010, at 13:57, J. Roeleveld wrote: > > ... > > With Raid (NOT striping) you can remove one disk, leaving the Raid- > > array in a > > reduced state. Then repartition the disk you removed, repartition > > and then re- > > add the disk to the array. > > Exactly. Except the partitions extend, in the same positions, across > all the disks. > > You cannot remove one disk from the array and repartition it, because > the partition is across the array, not the disk. The single disk, > removed from a RAID 5 (specified by Paul Hartman) array does not > contain any partitions, just one stripe of them. > > I apologise if I'm misunderstanding something here, or if your RAID > works differently to mine. > > Stroller. >
Stroller, it is my understanding that you use hardware raid adapters? If that is the case, then the mentioned method won't work for you and if your raid-adapters already align everything properly, then you shouldn't notice any problems with these drives. It would, however, be interesting to know how hardware raid adapters handle these 4KB sector-sizes. I believe Paul Hartman is, like me, using Linux Sofware raid (mdadm+kernel drivers). In that case, you can do either of the following: Put the whole disk into the RAID, eg: mdadm --create --level=5 --devices=6 /dev/sd[abcdef] Or, you create 1 or more partitions on the disk and use these, eg: mdadm --create --level=5 --devices=6 /dev/sd[abcdef]1 To have linux auto-detect for raid devices work, as far as I know, the partitioning method is required. For that, I created a single full-disk partition on my drives: -- # fdisk -l -u /dev/sda Disk /dev/sda: 1500.3 GB, 1500301910016 bytes 255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors Units = sectors of 1 * 512 = 512 bytes Disk identifier: 0xda7d8d6d Device Boot Start End Blocks Id System /dev/sda1 64 2930277167 1465138552 fd Linux raid autodetect -- I, after reading this, redid the array with the partition starting at sector 64. Paul was unfortunate to have already filled his disks before this thread appeared. The downside is: you loose one sector, but the advantage is a much improved performance (Or more precisely, not incur the performance penalty from having misaligned partitions) -- Joost Roeleveld
