Did you create the partition before you added the disk to mdadm or after? If after was it a dos or a gpt? Dos should have only cleared the first 512byte block. If gpt it will have written to the first block and to at least 1 more location on the disk, possibly causing data loss. If before then you at least need to get rid of the partition table completely. Having a partition on a device will often cause a number of things to ignore the whole disk. I have debugged "lost" pv's where the partition effectively "blocked" lvm from even looking at the entire device that the pv was one. If it is a dos partition table then: save a backup of each disk first (always a good idea, you can dd it back if you screwed up so long as you carefully create the backups and name them properly). dd if=/dev/sdx of=/root/sdxbackup.img bs=512 count=1 then clear the partition table space, rebooting is probably the easiest way to clear out the mappings, it can be done without rebooting but I have to do it trial and error to figure out the exact order and commands. dd if=/dev/zero of=/dev/sdX bs=512 count=1 On Tue, Jul 14, 2020 at 6:11 PM antlists <antlists@xxxxxxxxxxxxxxx> wrote: > > On 14/07/2020 20:50, Adam Barnett wrote: > > Forcing the assembly does not work: > > > > $ sudo mdadm /dev/md1 --assemble --force /dev/sd[ijmop]1 /dev/sd[kln] > > mdadm: /dev/sdi1 is busy - skipping > > mdadm: /dev/sdj1 is busy - skipping > > mdadm: /dev/sdm1 is busy - skipping > > mdadm: /dev/sdo1 is busy - skipping > > mdadm: /dev/sdp1 is busy - skipping > > mdadm: Cannot assemble mbr metadata on /dev/sdk > > mdadm: /dev/sdk has no superblock - assembly aborted > > Did you do an "mdadm --stop /dev/md1" before trying that? That's a > classic error from an array that's previously been partially assembled > and failed ... > > The other thing I'd do is make sure there aren't any other unepected > partially assembled arrays. I doubt it applies here, but I have come > across mirrors that get broken in half and you get two failed arrays > instead of one working one ... > > Cheers, > Wol
