Tuning for performance or reliability

[Jeff Silverman]

Jeff Silverman wrote:

> ...
> here might I find generally accepted
> benchmark software so I can measure Kernel and NFS efficientcy?
> ...

The Linux NFS howto, Chapter 5,
http://www.linuxdoc.org/HOWTO/NFS-HOWTO/performance.html#NFSD-INSTANCE, has an
answer:

Step 1:


 So we'll want to experiment and find an rsize and wsize that works and is as
fast as possible. You can test the speed of your options with some simple
commands.

 The first of these commands transfers 16384 blocks of 16k each from the special
file /dev/zero (which if you read it just spits out zeros _really_ fast) to the
mounted partition. We will time it to see how long it takes. So, from the client
machine, type:

    # time dd if=/dev/zero of=/mnt/home/testfile bs=16k count=16384


 This creates a 256Mb file of zeroed bytes. In general, you should create a file
that's at least twice as large as the system RAM on the server, but make sure
you have enough disk space!

Step 2:

Then read back the file into the great black hole on the client machine
(/dev/null) by typing the following:

    # time dd if=/mnt/home/testfile of=/dev/null bs=16k


 Repeat this a few times and average how long it takes. Be sure to unmount and
remount the filesystem each time (both on the client and, if you are zealous,
locally on the server as well), which should clear out any caches.

--
Jeff Silverman, sysadmin for the Research Computing Systems (RCS)
University of Washington, School of Engineering, Electrical Engineering Dept.
Box 352500, Seattle, WA, 98125-2500 FAX: (206) 221-5264 Phone (206) 221-5394
jeffs at rcs.ee.washington.edu     http://rcs.ee.washington.edu/~jeffs