CentOS NFS problem -- 30 seconds delay for "cat file"

[William Park]

On Tue, Apr 23, 2013 at 08:17:18PM -0700, DAVID CHIPMAN wrote:
> William,
> 
> Can we please see some strace output on the client side when you try
> to use cat to access a file on an NFS share? Please iuse the "-T"
> option for strace to get the time spent in system calls. Thanks,

There is nothing revealing about "strace".  It's taking all of its 30sec
at open(2) call... waiting for something.

    $ mount 192.168.2.3:/home /mnt -o ro
    $ strace -T cat /mnt/nfs/william/user-agent
    ...
    open("/mnt/nfs/home/william/user-agent", O_RDONLY|O_LARGEFILE) = 3 <30.033922>
    ...

This is from 32bit CentOS client.  From 64bit machines, it's 

    ...
    open("/mnt/william/user-agent", O_RDONLY) = 3 <30.059668>
    ...

I got tired of wiping/reinstalling distros to try out.  So, I had to use
bunch of KVMs.  It took me a while to figure out "bridge" mode so that
each VM has visible IP, because NFS server rejected connections from
NAT'ed VM...  something about "illegal port".  Anyways, here are results
from various clients:

    - Slackware -- instantaneous always
    - CentOS, Debian, Mint -- always 30sec hang at open(2)
    - Fedora, OpenSUSE, Ubuntu -- 30sec hang at first attempt to open
      the file, but immediate on subsequent tries.

At least, I learned about "bridge" mode of QEMU.  This all means that, I
have to use NFS to locate a file, and use SSH to open it.  Pain, but
I'll live with it.
-- 
William
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