Re: review of nfsd rc.d script patch

On 15 Jun, Rick Macklem wrote:
> Hi,
> 
> For the pNFS service MDS machine, the nfsd can't be started until all nfs mounts
> in /etc/fstab are done.
> I think that adding "mountcritremote" to the "# REQUIRE:" line is sufficient to do this?
> 
> I don't think delaying the startup of the nfsd daemon until after any NFS mounts
> are done will do any harm, but if others think it would be a POLA violation,
> I could make this dependent on the pNFS service being enabled.
> Does anyone think this would cause a POLA violation?

Sounds like that would break cross mounts.  Back in the olden days
before the automounter, I would set up workstation clusters with hosta
exporting local filesystem /home/hosta, and hostb exporting /home/hostb.
In addition, hosta would do a bg NFS mount of /home/hostb and hostb
would do a bg NFS mount of /home/hosta.  That way everybody would have a
consistent view of everything.  If a power failure took down everything,
the first system up would export its local filesystem and even though it
wouldn't be able to mount any remote filesystems, mount would background
itself at the boot would complete.  As the remaining machines came up,
they would be able to mount the remote filesystems of the machine that
came up earlier, and the early machines would mount the filesystems from
the later machines as they became available.

If nfsd is delayed until all the NFS filesystems are mounted, the above
setup would deadlock.