Crashes on Disk Spindown

Hi there,

I'm having a bit of a curious problem since a few days. My Server tends to crash sometimes when the disks are going to spindown.

Here's some output from a crash. It could spindown the disks fine a few times and then suddently it crashed at half past 4 in the morning:

Mar  9 00:02:48 nas kernel: mdcmd (93): spindown 2
Mar  9 00:09:44 nas kernel: mdcmd (94): spindown 4
Mar  9 00:38:26 nas kernel: mdcmd (95): spindown 3
Mar  9 00:39:37 nas kernel: mdcmd (96): spindown 2
Mar  9 01:28:43 nas kernel: mdcmd (97): spindown 3
Mar  9 01:28:50 nas kernel: mdcmd (98): spindown 2
Mar  9 01:30:04 nas kernel: mdcmd (99): spindown 4
Mar  9 01:51:25 nas kernel: mdcmd (100): spindown 2
Mar  9 01:51:26 nas kernel: mdcmd (101): spindown 3
Mar  9 02:25:57 nas kernel: mdcmd (102): spindown 3
Mar  9 02:27:24 nas kernel: mdcmd (103): spindown 2
Mar  9 02:34:07 nas kernel: mdcmd (104): spindown 4
Mar  9 02:40:01 nas root: mover: started
Mar  9 02:46:32 nas move: move: file /mnt/cache/nas/.sync/IgnoreList
Mar  9 02:46:32 nas move: move: file /mnt/cache/nas/.sync/ID
Mar  9 02:46:32 nas move: move: file /mnt/cache/nas/.sync/StreamsList
Mar  9 02:46:33 nas move: move: file /mnt/cache/nas/.sync/root_acl_entry
Mar  9 02:46:33 nas move: move: file /mnt/cache/nas/Files/.sync/IgnoreList
Mar  9 02:46:35 nas move: move: file /mnt/cache/nas/Files/.sync/ID
Mar  9 02:46:35 nas move: move: file /mnt/cache/nas/Files/.sync/StreamsList
Mar  9 02:46:35 nas move: move: file /mnt/cache/nas/Files/.sync/root_acl_entry
Mar  9 02:46:35 nas root: mover: finished
Mar  9 03:03:20 nas kernel: mdcmd (105): spindown 0
Mar  9 03:37:32 nas kernel: mdcmd (106): spindown 3
Mar  9 03:45:48 nas kernel: mdcmd (107): spindown 4
Mar  9 04:31:07 nas kernel: mdcmd (108): spindown 3
Mar  9 18:29:11 nas kernel: microcode: microcode updated early to revision 0x838, date = 2019-04-22
Mar  9 18:29:11 nas kernel: Linux version 4.19.107-Unraid (root@Develop) (gcc version 9.2.0 (GCC)) #1 SMP Thu Mar 5 13:55:57 PST 2020

It also often happens when I'm watching plex from things that are not stored on the cache drive.

I let MEMTEST run for 8 hours and it passed all tests.

Anyone has an idea what it could be?

Diagnostics are attached below.

nas-diagnostics-20200309-2109.zip