Mount Synology HDD under Linux

This article was published 1 year ago. Due to the rapidly evolving world of technology, some concepts may no longer be applicable.

My Synology DS214Play failed last week, and I replaced it with a QNAP TS-453A. However, as they use incompatible software the first thing that the QNAP wanted to do was erase my disks. I thought that RAID1 would be enough of a backup, so I didn’t have an external backup of the drives! Fortunately, I could plug one of the disks in to my desktop machine running Arch Linux and mount it manually, then copy all of the data from that disk on to another disk before wiping them.

In the following instructions, the disk I was working with was mounted as /dev/sdb

First, I tried to mount the disk in to a folder (some trial and error required to work out that /dev/sdb5 was the correct partition)

$ sudo mount /dev/sdb5 /media/test
mount: /media/test: unknown filesystem type 'linux_raid_member'.

Unknown filesystem type? Looks like I need to create a software RAID to mount it in to!

$ sudo mdadm --assemble --run /dev/md0 /dev/sdb5
mdadm: /dev/sdb5 is busy - skipping

Busy? But it’s not mounted. Let’s take a look

$ sudo mdadm --examine /dev/sdb 
/dev/sdb:
   MBR Magic : aa55
Partition[0] :   4294967295 sectors at            1 (type ee)

Run ls /dev/md then press tab to see what auto-completes. For me, it was /dev/md127. Let’s stop that and create a software RAID at /dev/md0

$ sudo mdadm --stop /dev/md127
$ sudo mdadm --assemble --run /dev/md0 /dev/sdb5
mdadm: /dev/md0 has been started with 1 drive (out of 2).

That’s correct! There were two drives and I’ve only provided one. Let’s mount it

$ sudo mount /dev/md0 /media/test
mount: /media/test: unknown filesystem type 'LVM2_member'.

Another unknown error. This is because it’s an LVM volume. Let’s see which are available using vgs

$ sudo vgs
  VG     #PV #LV #SN Attr   VSize VFree
  vg1000   1   1   0 wz--n- 5.45t    0

vg1000, I see you! Let’s mount that volume group now

sudo mount /dev/mapper/vg1000-lv /media/test

There we are! The disk was mounted and I could see all of the data in /media/test

Thoughts on this post

Som Won 2019-05-27

You made my day. (Saved my evening, actually). Thanks for sharing.

Jamie Costabile 2019-06-02

Hi Michael,

I wanted to give thanks! Your guide thoroughly helped me to access my data once again. I feel lucky to have found this and wished to share the luck :D

For future readers, I became stuck while stopping the /dev/md… step, and restarted – that worked for me. Then, on the last step my /dev/mapper/ had no vg1000-lv. A search for ‘mount LVM volume’ led me to https://www.cyberciti.biz/faq/linux-mount-an-lvm-volume-partition-command/ which allowed me to finish the job.

Appreciated,

Jamie

M 2019-06-05

Hey
I got exactly the same issue.
I had a DS212 with just one drive and the Synology went bust. My data is on the drive and I am wondering how I can access it and came across your post on your page.
I’ve gotten to the last step where I can see vg1000 listed just like your screenshot with the exact same listing except with 1.81t of data but when I try to mount /dev/mapper/vg1000-lv /media/test, I am returned with an error “mount: special device /dev/mapper/vg1000-lv does not exist.
Very new to the linux world and I am trying this out with the disk hooked up to a Raspberry Pi running Raspbian.
I installed mdadm and lvm2 after reading some posts to get this far btw :)
Do let me know if you have any ideas on how to proceed. Much appreciated.

Michael Heap 2019-06-09

Hey! Would Jamie’s response just above help?

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