Samba Load Testing at Brunel University

Tue May 4 14:20:34 GMT 1999

peter,

your comments are extremely helpful.

yes, we recommend between 600 and 800k per client (we did 2 years ago for
up to 1.9.17, no info on whether this recommendation has changed or not).

yes, 2.0.x should give your users a significant performance increase:
numbers i remember off top-of-head are somewhere around 20% (anyone care
to elaborate / point to NetBench tests?)

what happens on the home directory servers?  are those also samba?

best regards,

luke

On Wed, 5 May 1999, Peter Polkinghorne wrote:

> 
> BACKGROUND:
> 
> We wanted to find out how many PC clients our typical Sun server could
> support using Samba.
> 
> In the past we have had a figure of 30 class room or 100 office clients
> using PC-NFS, being supported by a Sparc 2 in a shared ethernet environment.
> However we now have switched fast ethernet, Windows NT 4.0 clients and Sun
> Ultra servers using Samba.  So how many clients will a server support in our
> new environment?  The support here means supplying PC applications,
> home directories are a separate service with different sizing requirements.
> 
> SET UP:
> 
> System: Cedar - Ultra 5/270 with 192Mb of memory and 4 & 8 Gb SCSI disks
> 	and Fast Ethernet (full duplex).
> 
> Software: Solaris 2.5.1 and Samba 1.9.18p10
> 
> Role: All NT applications software supplied to NT 4.0 sp3 workstations.
> 
> TEST:
> 
> This machine already serves around 200 NT clients - admin users.
> 
> We have around 450 NT clients on the campus - by map changes (NIS for those
> interested - we use NISgina), we moved them all in 3 stages to Cedar from the
> other 9 servers and observed the loading.  The extra clients comprised of
> around 80 class room PCs and 170 or so office machines used by staff and
> post grads.  The office machines are characterised by long login sessions
> and more diverse applications, whereas the classroom machines have short
> term use and tend to stick to word processing and web browsing.
> 
> I tested the responsiveness by using a NT client and measured time to
> login and time to load Word 97.  This enabled us to check whether the user
> perceived performance was acceptable.
> 
> RESULTS:
> 
> User:
> 
> To the user point of view - service did not degrade by and large.
> My measured login and Word 97 startup times did not change.
> One or two users had difficulty connecting - possibly due to the resource
> intensive nature of the logins - each smbd took 7 secs CPU just to service
> the login - this is something we are investigating from the client side.
> 
> System:
> 
> I used Samba Snap - see ftp://ftp.brunel.ac.uk/cc/peter/samba/
> a little perl utility that condenses smbstatus output to observe usage:
> 
>         Connections Shares  Files  %shared memory (400k)
> Normal:  120         300    2,500   33%
> Peak:    344         600    6,300   69%
> 
> The load on cedar did increase - the memory was not really adequate for the
> number of Samba processes - Swap space had to be raised to 460Mb.
> SAR indicated that the idle time went down to less than 20% for busy periods
> at peak test as opposed to 60% for normal load.
> 
> The disks did not from SAR appear to be too heavily loaded, apart from for
> swapping.
> 
> Network traffic at normal load is 300 k bytes a second (2.4 Mbps),
> whereas at peak it was 1000 k bytes a second (8 Mbps).
> 
> CONCLUSION:
> 
> Overall we were pleased that such a relatively lowly server could hand out
> PC applications to as many clients as well as that.
> 
> We plan to use Sun Ultras for supporting upto 60 classroom and 400 office NT
> workstations per server and ensure there is a reasonable mix of office and
> classroom machines.
> 
> OTHER THOUGHTS:
> 
> Using Samba 2.0.X should improve performance (or so I have been lead to
> believe).
> 
> With Solaris 7 (and other OSs) the noatime type mount options would help.
> 
> More memory would have helped cedar or may be we were hitting other barriers?
> 
> Client behaviour is important.
> 
> Can dig up more figures if useful ...
> 
> -- 
> -----------------------------------------------------------------------------
> | Peter Polkinghorne, Computer Centre, Brunel University, Uxbridge, UB8 3PH,|
> | Peter.Polkinghorne at brunel.ac.uk   +44 1895 274000 x2561       UK          |
> -----------------------------------------------------------------------------
> 
> 
> 

<a href="mailto:lkcl at samba.org"   > Luke Kenneth Casson Leighton  </a>
<a href="http://www.cb1.com/~lkcl"> Samba and Network Development </a>
<a href="http://samba.org"        > Samba Web site                </a>

=====================================================================
Luke Kenneth Casson Leighton        |  Direct Dial   : (678) 443-6183
Systems Engineer / ISS XForce Team  |  ISS Front Desk: (678) 443-6000
Internet Security Systems, Inc.     |  ISS Fax       : (678) 443-6477

http://www.iss.net/    *Adaptive Network Security for the Enterprise*
     ISS Connect   -   International User Conference   -  May '99
=====================================================================