I was asked by a friend if I am able to recover a crashed volume on a Synology DS207+, that was set up with a JBOD volume of 2 disks.
At some point the system crashed (probably a power outage) and it is left with a crashed volume.
It seems the volume 1 has forgotten about DISK 1 and is only showing DISK 2.
Looking at the disks themselves both are listed as working normally but DISK 1 is not initialized while disk 2 still belongs to Volume 1.
The disks are both identical 2 TB hard disks.
I have taken out both disks and ran a surface scan to rule out any faulty disks. Both disks came out clean with no bad sectors, which is why I have hope that maybe the volume can be simply put together again with no data loss.
I hooked the disks back up and SSH'd into the system to get to know more about the volume.
Disk /dev/sda: 2000.3 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 1 311 2490240 fd Linux raid autodetect Partition 1 does not end on cylinder boundary /dev/sda2 311 572 2097152 fd Linux raid autodetect Partition 2 does not end on cylinder boundary /dev/sda3 588 243201 1948793440+ fd Linux raid autodetect Disk /dev/sdb: 2000.3 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 311 2490240 fd Linux raid autodetect Partition 1 does not end on cylinder boundary /dev/sdb2 311 572 2097152 fd Linux raid autodetect Partition 2 does not end on cylinder boundary /dev/sdb3 588 243201 1948793440+ fd Linux raid autodetect
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] md2 : active linear sdb3 1948793408 blocks super 1.1 64k rounding [2/1] [_U] md1 : active raid1 sdb2 2097088 blocks [2/1] [_U] md0 : active raid1 sdb1 2490176 blocks [2/1] [_U] unused devices: <none>
Looks like there were multiple setups at some point. I looked into /etc/fstab to see what was currently set up:
/dev/root / ext3 defaults 1 1 none /proc proc defaults 0 0 /dev/md2 /volume1 ext3 defaults 0 0
So md2 is the active setup. I took a closer look at it.
mdadm --detail /dev/md2:
/dev/md2: Version : 01.01 Creation Time : Thu Feb 17 12:49:46 2011 Raid Level : linear Array Size : 1948793408 (1858.51 GiB 1995.56 GB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Sun Mar 10 11:36:50 2019 State : active, degraded Active Devices : 1 Working Devices : 1 Failed Devices : 0 Spare Devices : 0 Rounding : 64K Name : 2 UUID : 763a5c64:fbc0e3f6:fb3c451b:521efa98 Events : 7 Number Major Minor RaidDevice State 0 0 0 0 removed 1 8 19 1 active sync /dev/sdb3
Now I am getting into unfamiliar territory because I have never set up raids by hand before and I am unfamiliar with all that mdadm can do. I attempted to simply add the disk to the volume but that will not work.
mdadm --manage /dev/md2 --add /dev/sda3:
mdadm: add new device failed for /dev/sda3 as 2: Invalid argument
And the same with --re-add instead of --add.
I am now a tad afraid to proceed with any other commands when looking for similar issues and their solutions as I do not want to erase the data. Of course if there is no other way when I want to get the disks into a working order again then that is that. I know that JBODs are not the way to go without any additional means of backing up the data and my friend obviously does so now as well. :)
But it would still be great if I could somehow rescue this whole mess and in future set it up in a proper manner.
Alternatively, if the data on both disks can be rescued outside of the Synology Diskstation, this would be a valid solution as well. I have a spare 4 TB disk which could fit the data of the 2 2 TB disks. Can the data of the linux raid autodetect partitions simply be read and copied to the bigger disk?