[Summary] NFS buffering

Thanks to everyone who replied. 

It was a typical case of NFS client caching. The NFS clients, when
on default configuration (on Solaris anyway) will keep files cached
for 30 seconds. After the 30 seconds is expired, the client fetches
the file again and the tail command get a chunk of new lines all at
once.

This behavior can be corrected, if needed, by adding "actimeo=0" or
"noac" as an option to the nfs mount statement (through vfstab or
auto_*). But for larger environment, there may be a performance
penalty to pay so the option only for heavy write partitions where
realtime reading is required (like mail spool for example).

Thanks again.

On Fri, Jul 12, 2002 at 12:47:38PM -0400, Charles Gagnon wrote:
> I have an NFS buffer question,
> 
> - machine A and B are both mounting /dir from a NetApp filer.
> 
> - machine A runs an application that logs into /dir/file.log. App
>   logs about 1 line every 2-3 seconds.
> 
> - From machine A, the log is available "realtime". I can tail and
>   see the 1 line every 2-3 seconds.
> 
> - From machine B, the log will show up in chunks every 30-40
>   seconds. If I tail, I'll get like 20 lines every 40 seconds.
> 
> Question is who is buffering.
> 
>   Is it cached for writing on the NFS client?
>   Is it cached on the NFS server somehow?
> 
> Thanks for the help.
> 
> -- 
> Charles Gagnon                   | My views are my views and they
> http://unixrealm.com             | do not represent those of anybody
> charlesg@unixrealm.com           | but me.
> 
>    You can lead a mule to water, but you can't make him drink.
>    However, if you shoot a couple of uncooperative mules, the
>    rest tend to get pretty thirsty.
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-- 
Charles Gagnon                   | My views are my views and they
http://unixrealm.com             | do not represent those of anybody
charlesg@unixrealm.com           | but me.

   And whose cruel idea was it to put an "S" in the word "Lisp"?
        -- Dennis Miller
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