I have a bunch of old 1T disks with an mdadm array on them. They had been out of commission for awhile, but yesterday I slotted them into a server running an up to date Debian Jessie.
Eventually I got the array back together, but two drives refused to re-add. Looking at these drives, it appeared that I had somehow added the devices to the array rather than the (Linux RAID autodetect) partitions (sdz rather than sdz1) - I get what appears to be proper output for
mdadm -E /dev/sdz, but if I run
mdadm -E /dev/sdz1, I get
mdadm: cannot open /dev/sdz1: No such device or address.
Looking into it further, it seems that the partitions for these two drives are character special devices rather than block special:
root@comp:~# file /dev/sda1 # good drive /dev/sda1: block special (8/225) root@comp:~# file /dev/sdz1 # bad drive /dev/sdz1: character special (8/209)
Even after zeroing the entire bad drive with dd and recreating the partitions with fdisk, they still come back the same way! What's going on here?
Edit: Here's what ls says about these devices:
root@comp:~# ls -l /dev/sdz* brw-rw---- 1 root disk 65, 0 Feb 1 15:02 /dev/sdz cr-------- 1 root root 65, 1 Jan 31 18:31 /dev/sdz1
E2: Relevant numbers from /proc/partitions:
root@comp:~# cat /proc/partitions | egrep 'sdz|sda' 65 0 976762584 sdz 65 32 976762584 sda 65 33 976760832 sda1
I don't understand why the sdz partiton is not showing up here.