Re: NFS client renders system unusable

[mlelstv%serpens.de@localhost (Michael van Elst)]

pitney.brad%googlemail.com@localhost ("Brad Pitney") writes:

>On Sat, Mar 15, 2008 at 5:39 AM, Sarton O'Brien 
><bsd-xen%roguewrt.org@localhost> wrote:
>>  >> yp_order: clnt_call: RPC: Unable to send; errno = No buffer space
>>  >> available
>>  large amount of connections ... all those p2p connections would equate
>>  to nfs client conections.

I doubt that each client connection corresponds to one NFS connection.
There should be only one connection per NFS _mount_.

>Strange, when my NFS server goes away (maybe I've updated it and
>rebooted), my NFS clients just stall and wait for the server to come
>back, once it does, just resume as if nothing happened with exception
>of a few messages like this:
>Mar 13 00:13:44 nfs-client /netbsd: nfs server
>nfs-server:/media/data/netbsd/current/obj: not responding

I would guess that when the NFS connection stalls his application
just piles up connections. The number of open but waiting connection
grows beyond bounds and this is eating the (network) buffer space so
that finally even the single NFS connection fails due to lack
of memory.

The answer is to limit the number of open connections in his
application or if there is already a limit, to provide the
buffer resources necessary. With NetBSD this is the
kern.mbuf.nmbclusters value and maybe vm.nkmempages too.

-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."