On 11/10/17 22:56, Joseba Ibarra wrote:

Hi Adam

root@grafico:/mnt# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
[raid4] [raid10]
md0 : inactive sdd1[3] sdb1[1] sdc1[2]
      2929889280 blocks super 1.2

unused devices: <none>


root@grafico:/mnt# mdadm --manage /dev/md0 --stop
mdadm: stopped /dev/md0


root@grafico:/mnt# mdadm --assemble /dev/md0 /dev/sd[bcd]1
mdadm: /dev/md0 assembled from 3 drives - not enough to start the 
array while not clean - consider --force.



root@grafico:/mnt# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
[raid4] [raid10]
unused devices: <none>

At this point I´ve followed the advise using --force

root@grafico:/mnt# mdadm --assemble --force /dev/md0 /dev/sd[bcd]1
mdadm: Marking array /dev/md0 as 'clean'
mdadm: /dev/md0 has been started with 3 drives (out of 4).


root@grafico:/mnt# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
[raid4] [raid10]
md0 : active (auto-read-only) raid5 sdb1[1] sdd1[3] sdc1[2]
      2929889280 blocks super 1.2 level 5, 512k chunk, algorithm 2 
[4/3] [_UUU]
      bitmap: 0/8 pages [0KB], 65536KB chunk

unused devices: <none>


Now I see the RAID, however can't be mounted. So, I'm not sure how to 
backup the data. Gparted shows the partition /dev/md0p1 with the used 
and free space.

It still says read-only, can you try:
mdadm --manage /dev/md0 --run
or
mdadm --manage /dev/md0 --readwrite

PS, usually mounting will automatically convert from readonly to 
readwrite, but I recall some cases where this didn't happen for me, so 
it might help you as well.

Regards,
Adam

Joseba Ibarra

quoted

Adam Goryachev <mailto:adam@websitemanagers.com.au>
11 de octubre de 2017, 13:29
Hi Rudy,

Please send the output of all of the following commands:

cat /proc/mdstat

mdadm --manage /dev/md0 --stop

mdadm --assemble /dev/md0 /dev/sd[bcd]1

cat /proc/mdstat

mdadm --manage /dev/md0 --run

mdadm --manage /dev/md0 --readwrite

cat /proc/mdstat


Basically the above is just looking at what the system has done 
currently, stopping/clearing that, and then trying to assemble it 
again, finally, we try to start it, even if it has one faulty disk.

At this stage, chances look good for recovering all your data, though 
I would advise to get yourself a replacement disk for the dead one so 
that you can restore redundancy as soon as possible.

Regards,Adam

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