Hi,

One of our clients has a NAS attached as an NFS volume (mounted /nas).
The volume is being used by a Java webapp for storage purposes. Now,
one of the application's servlets calls tree(1) to quickly grab the
directory tree of a particular /nas subdirectory[1]. Occasionally, and
for unknown reasons, tree(1) blocks on I/O (ps ax shows a 'D' state).
This also affects the Java servlet container (Tomcat); several Java
processes get blocked on I/O, and the whole machine has to be cycled
to get things working again.

Now, my first suspect is the NFS volume, as that's the only place
being actively accessed by the webapp. I've heard some of the
complaints against NFS, but am not familiar with them.

Could someone enlighten me as to what may be happening in the above
situation? The machine admins have been resorting to cycling the
machine, and I can't think of a better solution as I'm not familiar
with NFS.


[1] You might ask: why not just use the Java class library? The short
answer is there isn't a quick and one-shot way (at least, AFAICT) to
grab the directory using any of the java.io classes, without resorting
to doing it recursively.

-- 
JM Ibanez
   - A million monkeys can't go wrong...
http://www.livejournal.com/~jmibanez/
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