frdb1001 became unresponsive without warning tonight. We checked central logs and didn't see anything informative, and attempting to log in via vsp failed, so I power cycled it. It came up with this POST message from the RAID controller:
313-HPE Smart Storage Battery 1 Failure - Battery Shutdown Event Code: 0x0400.
Action: Restart system. Contact HPE support if condition persists.
I don't see anything obvious in the OS, but did note that ssacli does not have this line which is present on a similar host:
"Cache Backup Power Source: Batteries", so I think it may have disabled write caching.