I have servers with failok option in /etc/fstab, like
/dev/ada3 /spool/3 ufs rw,noatime,noexec,failok 0 2
I expect, that server can boot if ada3 fails.
In practice server fails to boot and drops to single used mode with message like:
THE FOLLOWING FILE SYSTEM HAD AN UNEXPECTED INCONSISTENCY:
ufs: /dev/ada3 (/spool/3)
Unknown error; help!
ERROR: ABORTING BOOT (sending SIGTERM to parent)!
In fstab(5) failok documented as:
If the option “failok” is specified, the system will ignore any error
which happens during the mount of that filesystem, which would otherwise
cause the system to drop into single user mode.
But this option is not useful without fsck support.
How to fix:
fsck -p should ignore non-existing (non-readable) device for mount points with "failok" option.