Parity check started, many hours later I checked on it and came to a server with a GUI but the array was not started.  Said the parity check had errors, and after checking uptime it had obviously rebooted.  

 

Diags attached on the off chance that there's something useful there.

 

ffs2-diagnostics-20221021-1643.zip

Because of the reboot there's not much to see, enable the syslog server and try again, but a reboot is usually a hardware issue (or it lost power).

I restarted the parity check and woke up to the same condition... a rebooted server.  

 

I'll enable syslog and let it try again.

 

The only hardware change I've made in 10 years are disk changes, and I've upgraded two parity and one member disk in the last week.  

Turns out unraid has been writing syslogs to my pihole for a while after my last reboot failure, forgot I set that up.  After trimming a, 18GB log file, here's the last few hours from when I last interactively logged in, until this morning:

 

Oct 21 16:42:38 ffs2 kernel: eth0: renamed from vethef4de4f
Oct 21 16:42:38 ffs2 rc.docker: headphones: started succesfully!
Oct 21 16:42:39 ffs2 kernel: eth0: renamed from veth03888e9
Oct 21 16:42:39 ffs2 rc.docker: radarr: started succesfully!
Oct 21 16:42:39 ffs2 kernel: eth0: renamed from veth39d4e10
Oct 21 16:42:39 ffs2 rc.docker: sonarr: started succesfully!
Oct 21 16:42:40 ffs2 tips.and.tweaks: Tweaks Applied
Oct 21 16:42:40 ffs2 unassigned.devices: Mounting 'Auto Mount' Remote Shares...
Oct 21 16:42:40 ffs2 sudo:     root : PWD=/ ; USER=root ; COMMAND=/bin/bash -c /usr/local/emhttp/plugins/unbalance/unbalance -port 6237
Oct 21 16:42:40 ffs2 kernel: eth0: renamed from veth547d63d
Oct 21 16:42:41 ffs2 rc.docker: unifi-controller: started succesfully!
Oct 21 16:42:49 ffs2 unassigned.devices: Remote Share '//FFS1/backups' is not set to auto mount.
Oct 21 16:50:18 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 16:50:47 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1' 2>&1) took longer than 10s!
Oct 21 16:51:02 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1' 2>&1) took longer than 10s!
Oct 21 16:52:00 ffs2 root: Fix Common Problems Version 2022.10.17
Oct 21 16:54:15 ffs2 kernel: vethef4de4f: renamed from eth0
Oct 21 16:54:24 ffs2 kernel: veth03888e9: renamed from eth0
Oct 21 16:54:36 ffs2 kernel: veth39d4e10: renamed from eth0
Oct 21 17:02:09 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:05:24 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:05:39 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:15:01 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:16:39 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:16:53 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1' 2>&1) took longer than 10s!
Oct 21 17:18:09 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:18:38 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1' 2>&1) took longer than 10s!
Oct 21 17:19:24 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:20:52 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1' 2>&1) took longer than 10s!
Oct 21 17:22:09 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:23:43 ffs2 emhttpd: cmd: /usr/local/emhttp/plugins/dynamix/scripts/tail_log syslog
Oct 21 17:26:13 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:27:42 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1' 2>&1) took longer than 10s!
Oct 21 17:32:00 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1' 2>&1) took longer than 10s!
Oct 21 17:32:10 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:33:01 ffs2 unassigned.devices: Warning: shell_exec(/sbin/arp -a 'FFS1.local' 2>&1) took longer than 10s!
Oct 21 17:39:14 ffs2 sshd[23216]: Connection from 192.168.0.14 port 52014 on 192.168.0.5 port 22 rdomain ""
Oct 21 17:39:15 ffs2 sshd[23216]: Postponed keyboard-interactive for root from 192.168.0.14 port 52014 ssh2 [preauth]
Oct 21 17:39:16 ffs2 sshd[23216]: Postponed keyboard-interactive/pam for root from 192.168.0.14 port 52014 ssh2 [preauth]
Oct 21 17:39:16 ffs2 sshd[23216]: Accepted keyboard-interactive/pam for root from 192.168.0.14 port 52014 ssh2
Oct 21 17:39:16 ffs2 sshd[23216]: pam_unix(sshd:session): session opened for user root(uid=0) by (uid=0)
Oct 21 17:39:16 ffs2 sshd[23216]: Starting session: shell on pts/0 for root from 192.168.0.14 port 52014 id 0
Oct 21 17:48:47 ffs2 sshd[23216]: Connection closed by 192.168.0.14 port 52014
Oct 21 17:48:47 ffs2 sshd[23216]: Close session: user root from 192.168.0.14 port 52014 id 0
Oct 21 17:48:47 ffs2 sshd[23216]: pam_unix(sshd:session): session closed for user root
Oct 21 17:48:47 ffs2 sshd[23216]: Transferred: sent 734128, received 9136 bytes
Oct 21 17:48:47 ffs2 sshd[23216]: Closing connection to 192.168.0.14 port 52014
Oct 21 21:14:13 ffs2 ntpd[1687]: kernel reports TIME_ERROR: 0x41: Clock Unsynchronized
Oct 21 21:14:13 ffs2 rsyslogd: action 'action-2-builtin:omfwd' resumed (module 'builtin:omfwd') [v8.2002.0 try https://www.rsyslog.com/e/2359 ]
Oct 22 00:00:01 ffs2 kernel: mdcmd (37): check NOCORRECT
Oct 22 00:00:01 ffs2 kernel:
Oct 22 00:00:01 ffs2 kernel: md: check_array: not started
Oct 22 03:10:10 ffs2 ntpd[1704]: kernel reports TIME_ERROR: 0x41: Clock Unsynchronized
Oct 22 03:10:10 ffs2 rsyslogd: action 'action-2-builtin:omfwd' resumed (module 'builtin:omfwd') [v8.2002.0 try https://www.rsyslog.com/e/2359 ]
Oct 22 06:59:21 ffs2 webGUI: Successful login user root from 192.168.0.24
Oct 22 07:00:01 ffs2 crond[1725]: exit status 3 from user root /usr/local/sbin/mover &> /dev/null
Oct 22 07:06:08 ffs2 ool www[32507]: /usr/local/emhttp/plugins/dynamix/scripts/rsyslog_config
Oct 22 07:06:10 ffs2 rsyslogd: [origin software="rsyslogd" swVersion="8.2002.0" x-pid="483" x-info="https://www.rsyslog.com"] start
 

Nothing relevant logged, which is not that surprising since a reboot suggests a hardware or power problem.