[CentOS] [Solved] Excessive NFS operations

Robert Heller heller at deepsoft.com
Fri Oct 2 19:26:26 UTC 2009


At Fri, 02 Oct 2009 12:57:16 -0500 CentOS mailing list <centos at centos.org> wrote:

> 
> Robert Heller wrote:
> > 
> >>  
> >>>>  This is definitely a weird interaction, as neither the screensaver nor its
> >>>>  components actually run on the CentOS machine. I have not checked whether
> >>>>  any other activities in a vnc session cause similar behaviour.
> >>> Where does the screensaver's data files (eg where are the quotes stored)
> >>> live? If on the CentOS machine, then it is simply that the screensaver
> >>> is making lots of NFS I/O operations.
> >>  On the filer. But this retrieval script runs on the RHEL3 box(es).
> > 
> > The retrieval script is/was hitting on the file server to fetch the
> > quotes.  It probably was doing something dumb and not caching the
> > datafile.  This file access was beating on your file server.
> 
> Seems odd that caching wouldn't just happen naturally in the nfs client. 

I am not sure if it even makes sense to cache NFS files on a nfs client
-- how does the client know that the file might not have changed on the
server?  At the very least it has to check the file mod times on the
server to be sure its local cache is valid.

>   Maybe it is updating the access time on each read or something that 
> causes the activity.

It is either re-reading the files or checking mod times to determin
if the local cached copy is valid. Either way, lots of traffic.

> 

-- 
Robert Heller             -- 978-544-6933
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