Sharenfs on ZFS and mounting with autofs

Posted 25 March, 2020

zfs on linux

ZFS has this less documented feature, called share[nfs|smb]; I tried it once, it “did not work on first attempt”™ So I ignored it; However now we faced an issue where we normally exported ZFS volumes using /etc/exports (NFS); and mounted using /etc/fstab; but got an empty directory where there was a “sub” zpool volume; This seems counter intuitive as on the NFS exporting system you don’t see any difference in child pools directory structure;

For example : (on NFS server)

[[email protected] /]# zfs list
tinky              31.4T  49.0T      256K  /tinky
tinky/archive       219K  49.0T      219K  /tinky/archive
tinky/upload        219K  49.0T      219K  /tinky/upload

In order to export the full /tinky directory; we should do the following in /etc/exports :


This we can mount; and should give :


Which it does, yaaay ! Wrong ! All the data stored under /tinky/archive and /tinky/upload is invisible on the mount ! In fact these directories are empty.

Since zpool children are really easy (unlike human children) it would be really annoying to have to create a /etc/export and /etc/fstab entry for each of those childeren; There is a better way; using sharenfs option in ZFS and autofs (which I played around with already before, here).

In order to start the share with ZFS simply do :

zfs sharenfs=on tinky

You can check the result :

[[email protected] /]# zfs get all | grep nfs
tinky                 sharenfs              on                     local
tinky/archive         sharenfs              on                     inherited from tinky
tinky/upload          sharenfs              on                     inherited from tinky


[[email protected] ~]# showmount -e
Export list for tinky:
/tinky             *
/tinky/archive     *
/tinky/upload      *

If you want to restrict the shares or adapt the options; you can use :

zfs set sharenfs='[email protected]/16,[email protected]/24' tinky

in this case I restrict to two IP ranges; but go crazy. On issuing this command, they are automatically exported; which you can verify using exportfs

[[email protected] /]# exportfs

note : reduced output.

In case you don’t see it, you can try to share manually :

zfs share -a

and surprising, if you wish to un-share :

zfs unshare -a

On the remote machine, you can verify if you have access to the NFS mounts using showmount -e , using the IP of the NFS server;

# showmount -e
Export list for

The auto-mount itself now seems smarter then before; although I’m unsure exactly how, simply adding the root of the share is enough to see all the subvolumes in ZFS :

tinky       -rw,hard,intr,rsize=32768,wsize=32768,nfsvers=3\

Happy ZFS sharing 😉


// update

Turns out the issue is still there with this method;

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