NFS mounts with ZFS

I ran into a strange automount issue where my NFS shares were not being mounted at boot time. nfs/client was enabled, my entry in /etc/vfstab was correct, and issuing a `mount -a` worked flawlessly. So what was the problem? Well, this was the entry in my vfstab file:
biff:/paulie    -       /export/home/paulie/biff   nfs     -       yes     proto=tcp,vers=3
I wanted to place my NFS share inside a zfs filesystem so that it was easily accessible in my home directory.
[paulie@doc ~]$ zfs list | grep export/home/paulie
rpool/export/home/paulie  78.3M  2.82G  78.3M  /export/home/paulie
Turns out this is not such a good idea since the /etc/vfstab file is read *before* zpool's are imported and mounted. This means that all NFS shares need to be listed outside any filesystems to be mounted at boot time and then symlinked in.
[root@doc ~]# mkdir /biff
[paulie@doc ~]$ ln -s /biff/ /export/home/paulie/biff/
... and then changing around vfstab ...
biff:/paulie    -       /biff   nfs     -       yes     proto=tcp,vers=3
And that's it, NFS should automount now:
[paulie@doc ~]$ df -kh | grep biff
biff:/paulie           2.7T   1.2T       1.4T    47%    /biff
Lesson learned.
Comments:

The observation on the "initialization sequence" is key.
In the past I also run into issues with iSCSI and ZFS due to this.

An alternative to the presented case is to create a automounter's direct map.
This way the mounting would only be attempted later when actually accessed.

Regards.

Posted by Carlos Azevedo on January 16, 2014 at 02:05 AM MST #

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About

Hiya, my name is Paul Johnson and I'm a software engineer working on the ZFS storage appliance .

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