Here are some relevant lines from syslog:

    Aug 27 14:27:23 rune-desktop kernel: [    1.943848] md: bind<sdb1>
    Aug 27 14:27:23 rune-desktop kernel: [    1.958267] md: bind<sdc1>
    Aug 27 14:27:23 rune-desktop kernel: [    2.036123] md: bind<sdd1>
    Aug 27 14:27:23 rune-desktop kernel: [    2.037575] md: raid0 personality registered for level 0
    Aug 27 14:27:23 rune-desktop kernel: [    2.037679] md/raid0:md0: md_size is 3907045376 sectors.
    Aug 27 14:27:23 rune-desktop kernel: [    2.037682] md: RAID0 configuration for md0 - 1 zone
    Aug 27 14:27:23 rune-desktop kernel: [    2.037683] md: zone0=[sdc1/sdd1]
    Aug 27 14:27:23 rune-desktop kernel: [    2.037692] md0: detected capacity change from 0 to 2000407232512
    Aug 27 14:27:23 rune-desktop kernel: [    2.038966]  md0: unknown partition table
    Aug 27 14:27:23 rune-desktop kernel: [    2.231766] md: linear personality registered for level -1
    Aug 27 14:27:23 rune-desktop kernel: [    2.233460] md: multipath personality registered for level -4
    Aug 27 14:27:23 rune-desktop kernel: [    2.236043] md: raid1 personality registered for level 1
    Aug 27 14:27:23 rune-desktop kernel: [    2.480805] md: raid6 personality registered for level 6
    Aug 27 14:27:23 rune-desktop kernel: [    2.480807] md: raid5 personality registered for level 5
    Aug 27 14:27:23 rune-desktop kernel: [    2.480808] md: raid4 personality registered for level 4
    Aug 27 14:27:23 rune-desktop kernel: [    2.484824] md: raid10 personality registered for level 10
    Aug 27 14:27:23 rune-desktop kernel: [    2.523690] md/raid1:md2: active with 1 out of 2 mirrors
    Aug 27 14:27:23 rune-desktop kernel: [    2.523720] md2: detected capacity change from 0 to 2000263667712
    Aug 27 14:27:23 rune-desktop kernel: [    2.552606]  md2: unknown partition table
    Aug 27 14:27:24 rune-desktop mdadm[1706]: DegradedArray event detected on md device /dev/md2
    Aug 27 14:27:24 rune-desktop mdadm[1706]: DeviceDisappeared event detected on md device /dev/md0, component device Wrong-Level
    Aug 27 14:27:25 rune-desktop dbus[717]: [system] Activating service name='org.freedesktop.systemd1' (using servicehelper)
    Aug 27 14:27:25 rune-desktop dbus[717]: [system] Successfully activated service 'org.freedesktop.systemd1'
    Aug 27 14:27:30 rune-desktop udisksd[2754]: Error creating watch for file /sys/devices/virtual/block/md0/md/sync_action: No such file or directory (g-file-error-quark, 4)
    Aug 27 14:27:30 rune-desktop udisksd[2754]: Error creating watch for file /sys/devices/virtual/block/md0/md/degraded: No such file or directory (g-file-error-quark, 4)
    Aug 27 14:33:27 rune-desktop kernel: [  373.794337] md: bind<md0>
    Aug 27 14:33:27 rune-desktop kernel: [  373.832043]  disk 1, wo:1, o:1, dev:md0
    Aug 27 14:33:27 rune-desktop kernel: [  373.832103] md: recovery of RAID array md2
    Aug 27 14:33:27 rune-desktop kernel: [  373.832108] md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
    Aug 27 14:33:27 rune-desktop kernel: [  373.832110] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for recovery.
    Aug 27 14:33:27 rune-desktop kernel: [  373.832113] md: using 128k window, over a total of 1953382488k.
    Aug 27 14:33:27 rune-desktop kernel: [  373.832281] md: md2: recovery done.
    Aug 27 14:33:27 rune-desktop kernel: [  373.875909]  disk 1, wo:0, o:1, dev:md0
    Aug 27 14:33:27 rune-desktop mdadm[1706]: SpareActive event detected on md device /dev/md2