Neil great stuff, its online now!!! I followed your 2nd suggestion and ran mdadm --create /dev/md0 -f -l5 -n15 -c32 /dev/sd[bcdefghijklmnop]1 , after 8 hours we reached 99.9% and some errors appeared on sdh1 which was then kicked from archive but it was fully online. Ill see if any further errors are reported on sdh, but in the meantime I hotadded it back into the array which was successful. To my surprise a full fsck reported a clean volume. I am still unsure how this raid5 volume was partially readable with 4 disks missing. My understanding each file is written across all disks apart from one, which is used for CRC. So if 2 disks are offline the whole thing should be unreadable. Once again thanks for your help On 6/16/06, Neil Brown <neilb@xxxxxxx> wrote:
On Friday June 16, wilson150@xxxxxxxxx wrote: > > And is there a way if more then 1 disks goes offline, for the whole > array to be taken offline? My understanding of raid5 is loose 1+ disks > and nothing on the raid would be readable. this is not the case here. > Nothing will be writable, but some blocks might be readable. > All the disks are online now, what do I need to do to rebuild the array? Have you tried mdadm --assemble --force /dev/md0 /dev/sd[bcdefghijklmnop]1 ?? Actually, it occurs to me that that might not do the best thing if 4 drives disappeared at exactly the same time (though it is unlikely that you would notice) You should probably use mdadm --create /dev/md0 -f -l5 -n15 -c32 /dev/sd[bcdefghijklmnop]1 This is assuming that e,f,g,h were in that order in the array before they died. The '-f' is quite important - it tells mdadm not recover a spare, but to resync the parity blocks. NeilBrown
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