Red Hat Bugzilla – Bug 860497
rpc.mountd does not write to /var/lib/nfs/rmtab
Last modified: 2012-09-26 10:55:01 EDT
Description of problem:
Although an exported dir is mounted /var/lib/nfs/rmtab is empty (zero bytes). Additionaly showmount does not show remotely mounted dirs.
[root@gandalf BUILD]# grep nas /etc/fstab
nas:/data /nas nfs defaults,noauto,proto=tcp 0 0
[root@gandalf BUILD]# mount /nas
[root@nas nfs]# exportfs
[root@nas nfs]# showmount -a
All mount points on nas:
[root@nas nfs]# ll /var/lib/nfs/rmtab
-rw-r--r--. 1 root root 0 22. Jun 19:36 /var/lib/nfs/rmtab
Version-Release number of selected component (if applicable):
Steps to Reproduce:
rmtab with actuals mounts
Is gandalf mounting using NFSv4? If so, then this is expected behavior since there is no MNT request.
yes, the dir is mounted with nfsv4. Is this behaviour documented somewhere? The man page of mountd does not say that rmtab is not used with nfsv4. And how can I see which dirs are mounted on the server side? showmount does not work as expected.
Even with v2/v3, rmtab (hence showmount) isn't completely reliable. (And can't be: even if clients try to be good about sending mount/umount requests, the requests can get lost or duplicated.)
Agreed that it would be worth documenting this somewhere, I'm not sure where exactly.
mountd(8) already has this:
Note, however, that there is little to guarantee that the contents of
/var/lib/nfs/rmtab are accurate. A client may continue accessing an
export even after invoking UMNT. If the client reboots without sending
a UMNT request, stale entries remain for that client in
...I suppose it wouldn't hurt to update it with a blurb about NFSv4, but other than that I don't see that there's much we can do.
Yes, put it in each and every man page that deals with nfs. I googled a lot for the rmtab behaviour and it seems to be an unknown fact that nfsv4 does not use rmtab at all. Also document that it is impossible for the server side to keep track of its clients (which is really bad if you want to implement an automatic shutdown for a (idle) nas system).
(In reply to comment #5)
> Also document that it is impossible for the server
> side to keep track of its clients (which is really bad if you want to
> implement an automatic shutdown for a (idle) nas system).
That might still be doable by some other mechanism--if you want to discuss how, a good start would be a post to firstname.lastname@example.org explaining what you want to do.
Documentation patches also welcomed (I'd suggest starting just with the mountd man page, in nfs-utils).
The original complaint seems to describe as-designed behavior, though; closing.