Hi,
I've been unable to track down an extremely annoying performance issue
with NFS. My home server has several exports shared over NFS4. The
exports are all secured using Kerberos except one, which can be mounted
using the traditional sys security model.
The problem is that write performance stalls at 48k/sec (or according to
nfsiostat 4k/sec) despite being on a 1Gbit network and once this occurs,
nothing I do seems to fix it. The only thing that does, is rebooting the
client machine. This has been occurring for a year or so now but is
happening so regularly now, it's driving me nuts! :-)
I'm fairly sure it's a client side issue, because rebooting the client
allows normal transfer speeds once again. If I only reboot the server it
makes no difference. My client is F19, the server is F20. After
rebooting the client, write transfers can be fine for a day or so and
then all of a sudden it hangs around 48k/sec again.
Restarting all the NFS daemons on the client makes no difference,
including the associated RPC daemons. The NFS exports are mounted via
autofs, but manually mounting makes no difference either.
When I'm experiencing slow writes to the server of 48k/sec, NFS reads
are still in the region of 100MB/sec. Using scp or even copying files to
the server via CIFS are well within the range of a 1Gbit network.
Nfsstat, wireshark and the system logs do not show anything which
screams there's a problem.
The network card in the client machine and the server shows no
collisions, dropped packets, frame overruns etc.
I've tested with the export that isn't using Kerberos and still have the
same issue. Messing with the rsize, wsize, async, sync parameters makes
no difference either.
The server has 32GB RAM, the client 16GB.
For all intents and purpose it looks like its working as it should, it's
just painfully slow.
Any NFS gurus out there, that can tell me what I'm doing wrong?
--
Ian Chapman.
--
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