Making 3B2/310 faster

[jkj737 at uxf.cso.uiuc.edu]

/* Written  9:54 pm  Oct 17, 1988 by clp at beartrk.UUCP in uxf.cso.uiuc.edu:comp.sys.att */
/* ---------- "Making 3B2/310 faster" ---------- */
I have a client who is using a 3B2/310 for a relatively small (<10000 records)
database.  There are some users who are complaining that the machine is too
slow and would like to enhance the performance.  But they would like to do it
inexpensively if possible.

The current configuration is:  3B2/310, 2 Meg Memory, 72 MB disk, 2 Ports cards,
XM box with 23 MB tape drive.  Software is Sys V, rel 2.1.

I've talked with some other users who suggested that A) more memory might help,
B) a second disk might help, C) changing to Sys V, rel 3 might help.

I'm open to any suggestions, but in particular I'm curious about the following:

/* End of text from uxf.cso.uiuc.edu:comp.sys.att */

The first thing I would do is set up the performance utilities that come with
Unix (sar(1m) and the like) and take a weeks worth of data under normal
load.

Take a look at disk activity, and memory swapping stats to see where 
the bottleneck is.  

If you have a LOT of disk activity and very little memory swapping, you 
probably need a second disk to offload some of the work.  Unix works best 
with swap and / on one disk /usr on second.  This minimizes head movement 
and reduces the amount of time waiting for i/o (wio). It balances the disk 
use more evenly between both drives.

If you have a LOT of memory swapping, you don't have enough memory so Unix is
constantly swapping memory out to disk which will hurt if you also are
doing a lot of disk activity as well.  You probably should look at getting
more memory.

You should also look at performance verses number of users.  The 310's
ports cards are dumb (almost) and cause more overhead than the new eports
we use on the 600.  You could have too many users for a 310.

Release 3.1 does have nice features like demand paging and shared
libraries, but these come at a price.  The overhead is slightly higher, so
depending of machine use it may or may not help.  I have found that our 300
running 3.1 is a total dog.  A 310 should fair a little better.

As my computer architecture professor said, "The only way to may a good 
decision is to not make a stupid one."  (ie. don't change ANYTHING until 
you look are the system activity reports for the normal system load and
verify the bottlenecks.)  Be sure to use all the options of SAR(1M) available.

#include<disclaimer.h>

Jeff Johnson
Global Information Systems Technology, Inc.
1800 Woodfield Drive
Savoy, IL  61874

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