On Tue, Mar 10, 2020 at 02:20:02PM -0700, Song Liu wrote: > On Sun, Mar 8, 2020 at 7:15 AM Chris Green <cl@xxxxxxxx> wrote: > > > > Well I've got it working again but I'm very confused as to *why* it > > failed the way it did. > > > > A 'cat /proc/mdstat' produced:- > > > > Personalities : [linear] [raid0] [raid1] > > md4 : active raid1 sda4[0] > > 973522816 blocks [2/1] [U_] > > > > md1 : active raid1 sdb2[0] sda2[1] > > 256960 blocks [2/2] [UU] > > > > md3 : active raid1 sdb3[0] sda3[1] > > 987904 blocks [2/2] [UU] > > > > md2 : active raid1 sdb4[0] > > 973522816 blocks [2/1] [U_] > > > > md0 : active raid1 sdb1[0] sda1[1] > > 1959808 blocks [2/2] [UU] > > > > So md2 and md4 (the main parts of the two 1Tb disk drives) seemed to > > be OK from the RAID point of view. But I noticed that the block > > device for /dev/md4 didn't exist:- > > > > ~ # ls -l /dev/md* > > brw-r----- 1 root root 9, 0 Sep 29 2011 /dev/md0 > > brw-r----- 1 root root 9, 1 Sep 29 2011 /dev/md1 > > brw-r----- 1 root root 9, 10 Sep 29 2011 /dev/md10 > > brw-r----- 1 root root 9, 11 Sep 29 2011 /dev/md11 > > brw-r----- 1 root root 9, 12 Sep 29 2011 /dev/md12 > > brw-r----- 1 root root 9, 13 Sep 29 2011 /dev/md13 > > brw-r----- 1 root root 9, 14 Sep 29 2011 /dev/md14 > > brw-r----- 1 root root 9, 15 Sep 29 2011 /dev/md15 > > brw-r----- 1 root root 9, 16 Sep 29 2011 /dev/md16 > > brw-r----- 1 root root 9, 17 Sep 29 2011 /dev/md17 > > brw-r----- 1 root root 9, 18 Sep 29 2011 /dev/md18 > > brw-r----- 1 root root 9, 19 Sep 29 2011 /dev/md19 > > brw-r----- 1 root root 9, 2 Sep 29 2011 /dev/md2 > > brw-r----- 1 root root 9, 20 Sep 29 2011 /dev/md20 > > brw-r----- 1 root root 9, 21 Sep 29 2011 /dev/md21 > > brw-r----- 1 root root 9, 22 Sep 29 2011 /dev/md22 > > brw-r----- 1 root root 9, 23 Sep 29 2011 /dev/md23 > > brw-r----- 1 root root 9, 24 Sep 29 2011 /dev/md24 > > brw-r----- 1 root root 9, 25 Sep 29 2011 /dev/md25 > > brw-r----- 1 root root 9, 26 Sep 29 2011 /dev/md26 > > brw-r----- 1 root root 9, 27 Sep 29 2011 /dev/md27 > > brw-r----- 1 root root 9, 28 Sep 29 2011 /dev/md28 > > brw-r----- 1 root root 9, 29 Sep 29 2011 /dev/md29 > > brw-r----- 1 root root 9, 3 Sep 29 2011 /dev/md3 > > brw-r----- 1 root root 9, 5 Sep 29 2011 /dev/md5 > > brw-r----- 1 root root 9, 6 Sep 29 2011 /dev/md6 > > brw-r----- 1 root root 9, 7 Sep 29 2011 /dev/md7 > > brw-r----- 1 root root 9, 8 Sep 29 2011 /dev/md8 > > brw-r----- 1 root root 9, 9 Sep 29 2011 /dev/md9 > > > > > > The fix was simply to use 'mknod' to create the missing /dev/md4, now > > I can mount the drive and see the data. > > > > What I don't understand is where /dev/md4 went, how would it have got > > deleted? I have yet to reboot the system to see if /dev/md4 > > disappears again but if it does it's not a big problem to create it > > again. > > > > Should the RAID block devices get created as part of the RAID start > > up? Maybe there's something gone awry there. > > Do you have proper /etc/md.conf? > There is no /etc/md.conf or anything that I can see related to RAID configuration anywhere in the system. -- Chris Green
