NFS server usage

Michael Conlen meconlen at
Thu Feb 26 13:58:31 PST 2004

On Feb 26, 2004, at 4:33 PM, Charles Swiger wrote:

> Well, you are going to be bottlenecked potentially by your network or 
> by the maximum I/O rate that your NFS server can sustain.  Your data 
> suggests you ought to be able to handle about two orders of magnitude 
> more net traffic, if you're over a dedicated 100 Mbs connection 
> between server and clients (ie, using a switch), so it's likely that 
> you're going to run into limits due to your disks well before then.
> You can probably switch to using rsync or some other replication 
> scheme instead of NFS if you do run into limits, and keep the files 
> locally if need be.

The production system will use dual channel U320 RAID controllers with 
12 disks per channel, so disk shouldn't be an issue, and it will 
connect with GigE, so network is plenty fine, now I'm on to CPU.

Low volume tests with live data indicate low CPU  usage however when I 
best fit the graph it's dificult to tell how linear (or non linear) the 
data is. I've got a ton of points between 7.5Mbit/sec web traffic and 
and 17Mibt/sec but all the points beyond that are somewhat scattered up 
to about 23Mibt/sec (with a corresponding 5% load in NFS traffic.) The 
first interval is pretty linear but the first and second interval are 
not and appear exponential, and the numbers indicate that a 2Gz Xeon 
system that's using 2% CPU around 8Mbit in web traffic and 3% around 15 
Mbit suddenly using 50% CPU at 52Mbit and 250% at 75Mbit. (presuming 5% 
of that traffic ends up actually going over NFS). Does that kind of 
curve look accurate to you (anyone)?

Would a web page with pretty pictures help anyone understand what I 
just said?

Michael Conlen

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