Solaris fssnap and realtime processes

fsnap(1M) is most woo-esque for backing up filesystems, in a

• snapshot filesystem
• dump filesystem to tape
• release snapshot
• check dump

kind of manner.

It does, however, have problems with realtime priority processes. If the executable of such a process resides on the filesystem being snapshotted, things don't work: snapshot error: File system could not be write locked

Quick solution: identify these processes and halt them across the snapshot:

#   priocntl -d -i class RT
REAL TIME PROCESSES:
    PID    RTPRI       TQNTM
    577       0           0       

In this case, pid 577 was xntpd(1M).

Perhaps a better attempt would be to temporarily jigger the priority away from realtime.