Linux NFSv4 clients are getting (bad sequence-id error!)

[Ahmed Kamal]

Hi again Rick,

Seems that I'm still being unlucky with nfs :/ I caught one of the newly
installed RHEL6 boxes having high CPU usage, and bombarding the BSD NFS box
with 10Mbps traffic .. I caught a tcpdump as you mentioned .. You can
download it here:

https://dl.dropboxusercontent.com/u/51939288/nfs41-high-client-cpu.pcap.bz2

I didn't restart the client yet .. so if you catch me in the next few hours
and want me to run any diagnostics, let me know. Thanks a lot all for
helping

On Thu, Jul 23, 2015 at 11:59 PM, Rick Macklem <rmacklem at uoguelph.ca> wrote:

> Ahmed Kamal wrote:
> > Can you please let me know the ultimate packet trace command I'd need to
> > run in case of any nfs4 troubles .. I guess this should be comprehensive
> > even at the expense of a larger output size (which we can trim later)..
> > Thanks a lot for the help!
> >
> tcpdump -s 0 -w <file>.pcap host <client-host-name>
> (<file> refers to a file name you choose and <client-host-name> refers to
>  the host name of a client generating traffic.)
> --> But you won't be able to allow this to run for long during the storm
> or the
>     file will be huge.
>
> Then you look at <file>.pcap in wireshark, which knows NFS.
>
> rick
>
> > On Thu, Jul 23, 2015 at 11:53 PM, Rick Macklem <rmacklem at uoguelph.ca>
> wrote:
> >
> > > Graham Allan wrote:
> > > > For our part, the user whose code triggered the pathological
> behaviour
> > > > on SL5 reran it on SL6 without incident - I still see lots of
> > > > sequence-id errors in the logs, but nothing bad happened.
> > > >
> > > > I'd still like to ask them to rerun again on SL5 to see if the
> "accept
> > > > skipped seqid" patch had any effect, though I think we expect not.
> Maybe
> > > > it would be nice if I could get set up to capture rolling tcpdumps of
> > > > the nfs traffic before they run that though...
> > > >
> > > > Graham
> > > >
> > > > On 7/20/2015 10:26 PM, Ahmed Kamal wrote:
> > > > > Hi folks,
> > > > >
> > > > > I've upgraded a test client to rhel6 today, and I'll keep an eye
> on it
> > > > > to see what happens.
> > > > >
> > > > > During the process, I made the (I guess mistake) of zfs send |
> recv to
> > > a
> > > > > locally attached usb disk for backup purposes .. long story short,
> > > > > sharenfs property on the received filesystem was causing some
> > > nfs/mountd
> > > > > errors in logs .. I wasn't too happy with what I got .. I
> destroyed the
> > > > > backup datasets and the whole pool eventually .. and then rebooted
> the
> > > > > whole nas box .. After reboot my logs are still flooded with
> > > > >
> > > > > Jul 21 05:12:36 nas kernel: nfsrv_cache_session: no session
> > > > > Jul 21 05:13:07 nas last message repeated 7536 times
> > > > > Jul 21 05:15:08 nas last message repeated 29664 times
> > > > >
> > > > > Not sure what that means .. or how it can be stopped .. Anyway,
> will
> > > > > keep you posted on progress.
> > > >
> > > Oh, I didn't see the part about "reboot" before. Unfortunately, it
> sounds
> > > like the
> > > client isn't recovering after the session is lost. When the server
> > > reboots, the
> > > client(s) will get NFS4ERR_BAD_SESSION errors back because the server
> > > reboot has
> > > deleted all sessions. The NFS4ERR_BAD_SESSION should trigger state
> > > recovery on the client.
> > > (It doesn't sound like the clients went into recovery, starting with a
> > > Create_session
> > >  operation, but without a packet trace, I can't be sure?)
> > >
> > > rick
> > >
> > > >
> > > > --
> > > >
> -------------------------------------------------------------------------
> > > > Graham Allan - gta at umn.edu - allan at physics.umn.edu
> > > > School of Physics and Astronomy - University of Minnesota
> > > >
> -------------------------------------------------------------------------
> > > >
> > > >
> > >
> >
>