Now that I actually started to invistigate the problem myself in earnest, I am really getting to know my Synology DiskStation quite a bit.

Part of the process is to familiarize myself with the layout of the system and the various command line utilities available for inspecting status and history. Surely there are quite a few graphical tools which come as part of the operating system, but you really want to drill down on details there is not other way than to get in there via the terminal.

Nicely enough the DiskStation Manager (DSM) is based on the Linux Kernel, thereby resulting in a directory layout for the system, which is rather familiar. So with a little bit of reading up and exploring it is possible to find the relevant configuration files and inspection tools. So after poking around a bit, here is where I am at right now:

(a) Check log with system messages

Going through the entries of /var/log/messages I noticed that the system failed to assemble the volume associatd with /dev/md4, which I guess is my main data volume (the one currently labeled as “crashed”).

Dec 28 12:29:05 DiskStation spacetool.shared: spacetool.c:1069 Try to force assemble RAID [/dev/md4]. [0x8000 raid_ioctl_info.c:55]
Dec 28 12:29:05 DiskStation spacetool.shared: raid_allow_rmw_check.c:48 fopen failed: /usr/syno/etc/.rmw.md6
Dec 28 12:29:06 DiskStation kernel: [   56.303999] md: md5: current auto_remap = 0
Dec 28 12:29:06 DiskStation kernel: [   56.304006] md: reshape of RAID array md5
Dec 28 12:29:06 DiskStation kernel: [   56.400306] md: md3: current auto_remap = 0
Dec 28 12:29:06 DiskStation spacetool.shared: raid_allow_rmw_check.c:35 Failed to get RAID '/dev/md4' info.
Dec 28 12:29:06 DiskStation spacetool.shared: raid_enable_multithread.c:42 Failed to get RAID '/dev/md4' info.
Dec 28 12:29:06 DiskStation spacetool.shared: spacetool.c:1097 Fail to enable multithread of [/dev/md4]
Dec 28 12:29:09 DiskStation spacetool.shared: spacetool.c:2835 [Info] Old vg path: [/dev/vg1000], New vg path: [/dev/vg1000], UUID: [ThEUxo-6Fl7-3hp0-dBir-xQE6-TRE1-nmleBS]
Dec 28 12:29:09 DiskStation spacetool.shared: spacetool.c:2842 [Info] Activate all VG
Dec 28 12:29:10 DiskStation spacetool.shared: lvm_vg_activate.c:23 Failed to do '/sbin/vgchange -ay /dev/vg1000'
Dec 28 12:29:10 DiskStation spacetool.shared: spacetool.c:2851 Failed to activate LVM [/dev/vg1000]
Dec 28 12:29:10 DiskStation spacetool.shared: spacetool.c:2896 space: [/dev/vg1000]
Dec 28 12:29:10 DiskStation spacetool.shared: spacetool.c:2922 space: [/dev/vg1000], ndisk: [34]

(b) Check on the RAID devices

With the information from the system log next up is a look at the lists of RAID devices and their associated drives/partitions:

  cat /proc/mdstat

As it turns out md4 indeed is missing from that list, hence little surprise the volume is not brought up:

Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md5 : active raid5 sdc6[12] sdb6[13] sda6[11] sdk6[10] sdj6[8] sdi6[7] sdg6[5] sdh6[6] sdf6[4] sde6[2] sdd6[1]
      5372034624 blocks super 1.2 level 5, 64k chunk, algorithm 2 [12/11] [UUUUUUU_UUUU]

md3 : active raid5 sdh8[0] sdb8[9] sdc8[8] sda8[7] sdk8[6] sdj8[3] sdi8[2] sdg8[1]
      7813942272 blocks super 1.2 level 5, 64k chunk, algorithm 2 [9/8] [UUU_UUUUU]

md6 : active raid5 sdc9[0] sdb9[1]
      5860301056 blocks super 1.2 level 5, 64k chunk, algorithm 2 [3/2] [UU_]

md1 : active raid1 sdl2[11] sdk2[10] sdj2[9] sdi2[8] sdh2[7] sdg2[6] sdf2[5] sde2[4] sdd2[3] sdc2[2] sdb2[1] sda2[0]
      2097088 blocks [12/12] [UUUUUUUUUUUU]

md0 : active raid1 sdl1[11] sdb1[10] sda1[1] sdc1[2] sdd1[5] sde1[7] sdf1[6] sdg1[3] sdh1[4] sdi1[8] sdj1[9] sdk1[0]
      2490176 blocks [12/12] [UUUUUUUUUUUU]

unused devices: <none>

(c) Re-assemble volume

This is the next step now. At the moment I am collecting as much information as I possibly can in order to re-assemble the volume. Part of this effort is reading through contributions on the Online Community Forum – given the fact that the problem I am confronted with seems not to be too uncommon, there is quite some discussion to be found online… hopefully with some pointers into the right direction.