Cannot mount a nfs share after doing a snapshot

Jose Garcia Juanino jjuanino at
Sun Jan 6 08:38:37 PST 2008

Hi Greg

El domingo 06 de enero a las 15:41:21 CET, Greg Byshenk escribió:
> On Sat, Jan 05, 2008 at 11:28:31PM +0100, Jose Garcia Juanino wrote:
> > I have a 7.0-PRERELEASE i386 system with a nfs server, with an unique export
> > line in /etc/exports file:
> > 
> > / -maproot=root -network -mask
> > 
> > After a reboot, I have no problem mounting this nfs share from a nfs client.
> > But after issuing the following command on the server:
> > 
> > # mount -u -o snapshot /.snap/now /
> Is the problem that you are trying to mount your snapshot on top of the /
> directory?  I use snapshots, but have never tried to do this, and can 
> imagine that there might be a problem, since the snapshot is itself a
> snapshot of a filesystem (different than the actual root filesystem).
> That would explain the error:
> > Jan  5 22:47:03 gauss mountd[542]: can't delete exports for /: Cross-device link

No, I am not trying to mount the snapshot. I am just taking (making) the
snapshot, as man mount says.

> What happens if you create a directory and mount your snapshot there:
> 	mkdir /snapshotmount
> 	mount -u -o snapshot /.snap/now /snapshotmount
> If this works, then you may need a separate exports line for /snapshotmount.

# file /.snap/now
/.snap/now: Unix Fast File system [v2] (little-endian) last mounted on
/, last written at Sun Jan  6 16:24:19 2008, clean flag 1, readonly flag
1, number of blocks 130721, number of data blocks 126520, number of
cylinder groups 4, block size 16384, fragment size 2048, average file
size 16384, average number of files in dir 64, pending blocks to free 0,
pending inodes to free 0, system-wide uuid 0, minimum percentage of free
blocks 8, TIME optimization

# mkdir /snapshotmount
# mount -u -o snapshot /.snap/now /snapshotmount
mount: /.snap/now : Invalid argument

The commands crashes becuase /snapshotmount is not a file system.

> If this fails, does it work if you use the more roundabout mount?  That is
> 	mdconfig -a -t vnode -f /.snapn/now -u 4
> 	mount -r /dev/md4 /snapshotmount

Take into account that /.snap/now snapshot did not exists before, thus
your first command fails:

# mdconfig -a -t vnode -f /.snap/now -u 4
mdconfig: could not open /.snap/now: No such file or directory

Thanks a lot for your reply.

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