number of nfsd processes

[Monty Mullig]

Many thanks to those who responded to my question about choosing a good
number of nfsd processes to run.  Here is a summary of responses that I
received.  I have excluded Piercarlo Grandi's response.  Because of its
length and the fact that it was posted to sun-spots directly, I thought it
best just to reference his posting, V9N6.  Piercarlos differs from others
in his approach and strong aversions to increasing the number of nfsd
processes.  It was also very thorough.

========================================

X-From: blc at sol.med.ge.com (Brett Chapman  x5156	)

Even though the man page says 4, eight is actually the real number.  I
don't think that too many will hurt, but too few will definitely slow
things down!

If you have a copy of 'top', you can watch the process load, and see how
long, often, and how many of the nfsds are active.  If all are ever
active, then increasing the number of nfsds would be a good idea.

X-From: ncr-fc!chuckp at bach@ccncsu.ColoState.EDU (Chuck Phillips)

The man page for nfsd suggest that "four is a good number" of nfsd process
to start, but doesn't give any further information on how to choose the
best number to start.  We have 10 diskless clients and about 20 PCs
running off of a 4/280 and our diskless 3/50s have recently begun to run
noticably slower (we just added 4).  Should we increase the nfsd processes
?  our 4/280 has one controller on each drive, with the client swap
partitions on a rimfire controller and a hitachi 892 MB drive.  we have 32
MB on the 4/280.

Because we have a large network, our servers run 6 biod's and 8 nfsd's.
If your PCs are running NFS, you probably should up the number of nfsd's.

The down side of increasing the number of nfsd's on a Sun 4 server is that
it can increase the load factor by that much more during times of heavy
NFS activity.  As your probably know, the current Sun 4's are lousy at
context switching.  I saw a review in a "UNIX World" "Tested Mettle"
column a graph of throughput vs. load factor for a Sun 4.  At a load
factor of 5, the Sun 4 throughput reduced by half.  Neat, eh?  However,
this seems to be a common drawback of RISC systems.

X-From: metaphor!aspen!ammon at decwrl.dec.com (Mike Ammon)

I also couldn't find the answer in the manual or from talking to sun.  I
got this information from Mt. Xinu at Usenix.

Each nfsd can handle one request at a time.  So, the number of
simultaneous requests can be up to the number of nfsds running.

Rules of thumb:

1) If the client response is slow add more nfsds.
2) If the server load is too high reduce the number of nfsds.
3) If a balance cannot be reached between 1) and 2) you need
   a faster server or more servers.

We have a 3/280 and about 40 clients (3/50 and 3/80).  All clients have
disks so there is no network swapping.  I am currently running 10 nfsds.
I noticed a big improvement going from 4 to 6, some improvement from 6 to
8 and little or no improvement from 8 to 10.

X-From: ames!omni.com!bob at ncar.UCAR.EDU (Bob Weissman)

Yes, increase the number of nfsd processes.

A good guess would be one nfsd per active client.  If all 10 of your
diskless nodes tend to doing real work simultaneously, you will want 10
nfsds.  If the PCs do a lot of NFS, you may need to increase the number
beyond that.

In fact, if your server is not a compute server (i.e., it's just an NFS
server and nobody does compiles on it), you may want to increase the nfsd
number even more.  The higher the number of nfsds, the less CPU will be
available for non-NFS stuff on your server.

From: alex <alexl%daemon.cna.tek.com at RELAY.CS.NET>

WIth 'ps axg', look at the TIME on your nfsd's.  If they are looking busy
in a short period of time, then maybe you could use some more.

Cant hurt to go to 8 for a while.