Hi Marnitz,

did you try mdadm assemble with -f (force)?

Cheers

Rudy

On 23-05-14 12:14, Marnitz Gray wrote:

Hello good people of linux-raid.

I come here seeking advice on how to repair my raid 5 which I have
managed to royally break.
The raid was initially created in 2009 with 5 1.5TB hdds. Since then I
have replaced 2 drives, 1 with a 2TB and 1 with a 3TB.
The current mdadm version is mdadm - v3.3 - 3rd September 2013
The /etc/debian_version file reads: jessie/sid

The story:
My intention was to replace all the 1.5TB drives with 3TB drives, and
then grow the size of the array.
Yesterday I replaced /dev/sdf, with a 3TB and re-sync'd the array.
The process finished sometime during the night with no errors, so this
morning I continued and replaced /dev/sdb. However, after booting the
machine I was unable to re-mount the partition (the error was on the
lines of: specify filesystem type).

After fumbling around with a couple of mdadm --assembles, removing the
new drive and replacing the old 1.5TB, re-trying some more assembles,
I stumbled upon the wiki article
(https://raid.wiki.kernel.org/index.php/RAID_Recovery) which led me
here.

I thus turn to the list seeking advice/help or simply guidance.
Attached is the current mdadm --examine of all drives, however, my
attempted assembles have clearly damaged something.

Heres the breakdown of the drives currently in the system (90% sure
this is correct):
/dev/sda: OS Hdd, not part of the raid
/dev/sdb: 1.5TB HDD removed this morning
/dev/sdc: 3TB added yesterday, replaced /dev/sdg
/dev/sdd: 2TB HDD, replaced a failed 1.5TB a few years back
/dev/sde: 1.5TB HDD, has not been replaced, should be part of the array
/dev/sdf: 3TB HDD, replaced a failed 1.5TB last year
/dev/sdg: 1.5TB HDD removed yesterday (replaced by /dev/sdc)

My assumption is that I need to try re-creating the array with drives b,c,d,e,f.

Here is the mdadm --assemble --force output for those drives:
mdadm --assemble --force --verbose /dev/md0 /dev/sdb /dev/sdc /dev/sdd
/dev/sde /dev/sdf
mdadm: looking for devices for /dev/md0
mdadm: /dev/sdb is identified as a member of /dev/md0, slot 3.
mdadm: /dev/sdc is identified as a member of /dev/md0, slot 5.
mdadm: /dev/sdd is identified as a member of /dev/md0, slot 2.
mdadm: /dev/sde is identified as a member of /dev/md0, slot 1.
mdadm: /dev/sdf is identified as a member of /dev/md0, slot 0.
mdadm: added /dev/sde to /dev/md0 as 1
mdadm: added /dev/sdd to /dev/md0 as 2
mdadm: added /dev/sdb to /dev/md0 as 3 (possibly out of date)
mdadm: no uptodate device for slot 8 of /dev/md0
mdadm: added /dev/sdc to /dev/md0 as 5
mdadm: added /dev/sdf to /dev/md0 as 0
mdadm: /dev/md0 assembled from 3 drives and 1 spare - not enough to
start the array.

Where did this all go wrong:
I believe the 3TB drive that I plugged in this morning came out of a
Seagate BlackArmor NAS400. It thus likely had other superblock
information on it which confused mdadm (purely speculative, I'm not
sure if this is even likely/possible).

I currently have 4 3TB drives spare, however, I do not have any spare
SATA ports to plug them into. While the data on the raid isn't
critical, I would be rather sad (and cry for many days) if it
disappeared.

Any suggestions welcome.

Thanks in advance,
Marnitz Gray