NFS4 mount finishes after 2 hours

[Jan Stilow <jstilow@mobileobjects.de>]

hello there,

I have a confusing problem to mount a nfs4 resource. The problem is that
the mount process take about 2 hours. Also it seems only to occur on VM
machines.

In my case the nfs-server and nfs-client are both VMs in VirtualBox.
Originally the problem occurred in a Xen environment but with VirtualBox
it is the same. So I used VirtualBox for my tests. On "real" machines
the problem did not occur. Server and Client are Debian Lenny machines
with a 2.6.26-2-amd64 (Debian 2.6.26-21lenny4) kernel.

At the point where mount is finished first all clients can connect as
fast as usual. During the mount process which takes about 2h you can
ping the server or open an ssh connection to the server. So only the nfs
mount seems to fail. After the time period you can unmount and mount at
will and as fast as usual.

Also interesting for me is that the problem only occurs after a
cold start of the VM but not when you restart the service or the VM. You
really need to shut down and reboot it to reproduce these behavior.

The output from a example mount and the /etc/exports configuration
follows at the end of these mail. The mount halts after the message
"mount.nfs4: pinging: prog 100003 vers 4 prot tcp port 2049". I also
tried different options in /etc/exports without success.

After you run "sysctl sunrpc.nfs_debug=1023" you can find "laundromat
service - starting" and "NFSD: laundromat_main - sleeping for 90
seconds" messages in your logs during the mount process. These messages
also repeat from time to time. Obviously the client communicates with
the server.

For me it looks like a problem with nfs and VM environments. So does
anyone have an idea?

Thanks in advance.

Kind regards,

Jan



/etc/exports:
^^^^^^^^^^^^^
/srv			192.168.56.102/32(rw,fsid=0,crossmnt,no_subtree_check)
/srv/test		192.168.56.102/32(rw,no_subtree_check)


The example mount:
^^^^^^^^^^^^^^^^^^
nfs4-client:~# time mount -vvv -t nfs4 192.168.56.101:/ /mnt/
mount: fstab path: "/etc/fstab"
mount: lock path:  "/etc/mtab~"
mount: temp path:  "/etc/mtab.tmp"
mount: spec:  "192.168.56.101:/"
mount: node:  "/mnt/"
mount: types: "nfs4"
mount: opts:  "(null)"
mount: external mount: argv[0] = "/sbin/mount.nfs4"
mount: external mount: argv[1] = "192.168.56.101:/"
mount: external mount: argv[2] = "/mnt/"
mount: external mount: argv[3] = "-v"
mount: external mount: argv[4] = "-o"
mount: external mount: argv[5] = "rw"
mount.nfs4: pinging: prog 100003 vers 4 prot tcp port 2049
192.168.56.101:/ on /mnt type nfs4 (rw)

real	118m46.858s
user	0m0.036s
sys	0m0.508s


Debug log messages:
^^^^^^^^^^^^^^^^^^^
May 18 15:21:24 nfs4-server kernel: [ 6322.206691] NFSD: laundromat
service - starting
May 18 15:21:24 nfs4-server kernel: [ 6322.206691] NFSD: laundromat_main
- sleeping for 90 seconds
May 18 15:22:54 nfs4-server kernel: [ 6412.209404] NFSD: laundromat
service - starting
May 18 15:22:54 nfs4-server kernel: [ 6412.221816] NFSD: laundromat_main
- sleeping for 90 seconds