Hi Neil, I'm probably doing something wrong since it's a pretty critical bug but can't see what. I'm creating a RAID1 array with 1.2 metadata. After that I stop the array, and restart the array with only one disk. I write random data on the array and then stop it again: # mkfs.ext4 /dev/md125 # mdadm --stop /dev/md125 # mdadm -IRs /dev/loop0 # mount /dev/md125 /mnt/ # date >/mnt/foo # umount /mnt # mdadm --stop /dev/md125 Finally I restart the array with the 2 disks (one disk is outdated) and mdadm happily activates the array without error. Note that I add the outdated disk first in that case: # mdadm -IRs /dev/loop1 mdadm: /dev/loop1 attached to /dev/md/array1, which has been started. # mdadm -IRs /dev/loop0 mdadm: /dev/loop0 attached to /dev/md/array1 which is already active. # cat /proc/mdstat Personalities : [raid1] md125 : active raid1 loop0[0] loop1[1] 117056 blocks super 1.2 [2/2] [UU] # mount /dev/md125 /mnt # ls /mnt/ [ 457.321771] EXT4-fs error (device md125): ext4_lookup:1047: inode #2: comm ls: deleted inode referenced: 12 ls: cannot access /mnt/1: Input/output error If I add the outdated disk last I got this: # mdadm -IRs /dev/loop0 mdadm: /dev/loop0 attached to /dev/md/array1, which has been started. # mdadm -IRs /dev/loop1 mdadm: can only add /dev/loop1 to /dev/md/array1 as a spare, and force-spare is not set. mdadm: failed to add /dev/loop1 to existing array /dev/md/array1: Invalid argument. which didn't tell me the reason why loop1 must be a spare. Is this expected ? If so could you enlight me ? Thanks -- Francis -- 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