Re: Massive NFS problems on large cluster with large number of mounts

Carsten Aulbert
2008-07-02T14:00:26Z

Hi all,

J. Bruce Fields wrote:
>
> I'm slightly confused--the above is all about server configuration, but
> the below seems to describe only client problems?

Well, yes and no. All our servers are clients as well. I.e. we have
~1340 nodes which all export a local directory to be cross-mounted.

>> (1) All our mounts use nfsvers=3 why is rpc.idmapd involved at all?
>
> Are there actually files named "idmap" in those directories? (Looks to
> me like they're only created in the v4 case, so I assume those open
> calls would return ENOENT if they didn't return ENFILE....)

No there is not and since we are not running v4 yet, we've disabled the
start for these on all nodes now.

>
>> (2) Why is this daemon growing so extremely large?
>> # ps aux|grep rpc.idmapd
>> root 2309 0.1 16.2 2037152 1326944 ? Ss Jun30 1:24
>> /usr/sbin/rpc.idmapd
>
> I think rpc.idmapd has some state for each directory whether they're for
> a v4 client or not, since it's using dnotify to watch for an "idmap"
> file to appear in each one. The above shows about 2k per mount?

As you have written in your other email, yes that's 2 GByte and I've
seen boxes where > 500 mounts hung that the process was using all of the
8 GByte. So I do think there is a bug.

OTOH, we still have the problem, that we can only mount up to ~ 350
remote directories. This one we think we tracked down to the fact that
the NFS clients refuse to use ports >1023 even though the servers are
exporting with the "insecure" option. Is there a way to force this?
Right now the NFS clients use ports 665-1023 (except a few odd ports
which were in use earlier).

Any hint for us how we shall proceed and maybe force the clients to also
use ports > 1023? I think that would solve our problems.

Cheers

Carsten