[Bug 1024313] Re: More than one client with nfs home directories will cause freeze

[Andrey Konstantinov]

Bad word choice on my side, of course downgrading to NFSv3 is not a fix,
but rather a workaround. We have also been using NFSv4 since 10.04 and
NFSv3 has problems with lock files, as far as I've heard, so of course
NFSv4 needs to be fixed.

Additional information (not sure if relevant to this bug but might be):
NFSv4 takes a minute or two to mount user home directories after boot so
one cannot login right away: "bootwait" option needs to be added to
/etc/fstab in order to make the machine wait until NFS home is mounted
and only display the login screen after. Again, this does not happen
with NFSv3 and did not happen with NFSv4 on 10.04. Whatever changes were
done to NFSv4 since 11.10, they only made things worse.

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Title:
  More than one client with nfs home directories will cause freeze

Status in “nfs-utils” package in Ubuntu:
  Confirmed

Bug description:
  Setup:

  2 similar company sites with one server and 5-10 clients. 
  Bug is preventing uppgrade of well working 10.04 system to 12.04
  Problem is becoming a real big issue since it is at the heart of company IT infrastructure.

  Server:
  Ubuntu 10.04 server amd64 running kernels 2.6.35-32-server or 3.0.0-22-server.
  Not tested with  standard/original kernel.
  Servers have a 6TB raid array and exports home and archive directories to clients and virtual servers using nfsv4.
  Services running on server: OpenLDAP, NFS, SAMBA, NTP, DHCP, DNS and KVM (with about 12 guests).

  Clients: 
  Several Ubuntu 10.04.4 clients with kernels 3.0.0-22 in the process of uppgrading (currently dual booting) to 12.04 (and in one case 11.10).
  All clients authenticates via LDAP and mounts home directories usig nfsv4 (static fstab mounts - no automounter).

  Setup with any number of 10.04 client and maximum of one 11.10 or
  12.04 client is working perfectly - thus we passed initial 12.04
  evaluation with flying collors..

  Bug description:
  When booting two or more 12.04 or 11.10 clients all 12.04 (or 11.10) clients will freeze at login of any two (random) users.
  This will often occurr instantly but at times after a  short delay.
  All 10.04 clients work well all the time - they are mounting the same shares but are not affected.
  Somtimes reboot from console is possibel on a frozen client but most often hard reset (poweroff on the button)  is required.
  After turing off the second 12.04 client the first one will be accesible again.

  As long as therie is only a single 11.10 or 12.04 client booted it
  will works as well as any 10.04...

  Have tried with tcp or udp, sync or async and all kinds of frame sizes etc - no change.
  Have replaced NICs to intel...
  Kubuntuo or Ubuntu does not matter....
  Found nothing usefull (!!?) in the logs this far...

  Network performance is very good with about 90 MB/s read/write speeds
  on nfs directories.

  (Only previous unsolved problem noted on 10.04 clients are bzr repos
  on nfs that will cause a freeze.)

  System seup is tradional and has been working for some 8 years and goes back before Ubuntu...
  (Still have some 8.04 clients that works exceptionally fine.)

  The funny thing is that we use kernel 3.0.0 on our 10.04 clients - same as the 11.10 client that is affected.
  Does this suggests it might not be a kernel issue after all?

  We will provide any assistance we are able to that is needed in order
  to solve this issue.

  Regards

  Hans Höök

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