On Mon, Mar 09, 2020 at 09:41:12AM +0000, Mark Rogers wrote:
On Sun, 8 Mar 2020 at 17:08, Chris Green cl@isbd.net wrote:
Yes, it has software RAID but no configuration files named anything like mdadm (or bits of it) in /etc. However there is the mdadm command available.
I know enough about mdadm that I could probably muddle through if your hardware was in front of me but not enough to explain or help much over email.
But I can say that raid configuration data is stored within the metadata in the arrays themselves and that whilst mdadm can have a configuration file it doesn't need one.
What does: cat /proc/mdstat tell you?
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]
Which led me to the answer (eventually), I was seeing the error (on the GUI) 'Failed to mount /dev/md4' but from the above md4 seemed to be OK. On looking in /dev I saw that /dev/md4 didn't exist, there was just:-
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, 2 Sep 29 2011 /dev/md2 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
So I added the missing block device using mknod (fortunately had root shell access to the NAS) and rebooted and everything now works perfectly. I have no idea why /dev/md4 disappeared though, it has survived several further reboots now so its disappearance seems to have been a one-off oddity.
Thanks for the help all.