News Group Posts

Comments on performance tuning kernel

parameters

This is a fairly detailed look at SCO Unix performance tuning. You might also want to read SCO Unix memory tuning.

More modern kernels tune for memory automatically. There is also the fact that today's hardware is very fast to begin with - fine tuning is seldom needed and, because the self tuning is probably much more competent than you are, is not usually indicated.

Message-ID: <3716BC71.7984EBC0@sodapop.org> 
From: John Gray <johng@sodapop.org>
Newsgroups: comp.unix.sco.misc,dropbox
Subject: Re: Scenario for the gurus
References: <oJxR2.273$Yy4.24794@news.uswest.net> 
Date: Thu, 15 Apr 1999 21:28:33 -0700

AWKYOU wrote:

> First let me thank Tony and Joseph for their responses.
>
> I need some more detailed help.
>
> Scenario: A network is somewhat dishevled. The platform is SCO
> a new server is being purchased and will run SCO Openserver 5.0.5.
> There is the stong possibility of another server being installed running NT.
> The main unix application uses Informix databases. The NT server will most
> likely be running something which uses SQL server. FacetWin may also be
> currently running. Your clients are both Win 9.x,  NT workstations  and some
> Macs.
>
> You want to provide the fastest most reliable network possible   with all of
> the above characteristics and you get to start from scratch.
>
> What do you do?
>
> please include answers to the following in your response
>
> What  can VisionFS do that AFPS can't?
> What can  AFPS do that VisionFS can't?
> Does FacetWin mean no AFPS as one posting here indicated?
> NoTechnology supports appletalk does Openserver?
> Why use a product like FacetWin ( besides terminal emulation) when you have
> VisionFS or AFPS?
> Whats the minimum hardware requirements you would use for the NT server ;the
> SCO server (60 clients on the network).
>
> Thanks in advance

I apologize if this has been covered before.I can't speak for the network
applications but don't forget the kernel tuning.  It can really
help the database engine and remove the slugish behaviour of a system.

Above all don't skimp on your swap area if meory will be tight.

Openserver 5.05 will use by default 10% of your total
memory for disk buffers with a cap of  about 6 meg by
default.  Depending on how much memory you have you can
starve the database engine.  This can be changed by running
configure in /etc/conf/cf.d.  select  1 and then alter
NBUF, each bufffer is 1K bytes.  NHBUF will auto size so
don't worry about that one.  If you have more  than   64
meg theres a good chance you may want to raise this.

By default PLOWBUFS  is 30 which will attempt to grab 30%
of the space allocated to your disk buffers and place them
below 16 meg.   If your system is PCI you won't need much
except for maybe your floppy.    No more than a meg of
low buffers will be needed.

Depending on how large your buffer cache is and how
many temp files get created and removed you may want to
increase, decrease or leave alone  the BDFUSHR parameter.
This is how often the kernel scans the disk buffers and
writes them out to disk.  The default is once every 30
seconds which may be perfect for your needs but you can
always adjust it.

For example if you do lots of compiles may raising it to
45 or 60 seconds may work wonders but the down side is
you leave your self more vunerable to disk corruption if
you have a kernel PANIC.

Selecting option 2 will allow you to adjust GPGSLO and
GPGSHI.  By default the kernel will wait until there are
about 25 pages (100k) left before it starts kicking out
dormant processes.  ( hopfully dormant :-) )   It will then
continue until there are 40 pages free (160k).  If you
are tight on memory this might be fine but if you have
more RAM then you may not want to wait around and bounce
around the limit of your memory.  It's really an art that
is system specific but being a little more agressive with
the GPGS lo and hi numbers may prevent some disk thrashing.

Option 7, since you are running a database, which may or
may not have many deamon running with it's user ID you may
need to up MAXUP.  This is the number of processes that
can belong to one single user at a time.  When running
large compiles I have found that I need to up this to 500
or my builds can fail.

Option 12, NSTRPAGES.  by default it is set to 500 which
is 2K.  If there is heavy network traffic this can be
raised also.  The pages are allocated as needed and this
number is a limit.   Using netsat -m to monitor the system
during peak loads might give you a good idea if it needs
to be increased.  ( wierd error messages too)

       
Options 13, 15 and 16 (messages queues, semaphores and
shared data) probably have some values that your database
vendor  can specify in  the documentation which is platform
specific.  Each database vendor will use these differently
and the kernel defaults are not optimal.

There is a good book that was written for 3.2V4 but
has lots of good info which details tuning your system
for databse performance.  It's  "The SCO Performance
Tuning Handbook" Gina Miscovich and David Simons.  ISBN
0-13-102690-9.    It was published in 1994.  Take this
into account when they talk about memory and cpu load.
The HW has changed a little.   :-)

Lastly I can't take much credit for what I have stated
here.  I have learned most of this from working with some
very talented people.

hope it helps
-john

Comments?

More Articles by Tony Lawrence - Find me on Google+

Jump to Comments

Many of the products and books I review are things I purchased for my own use. Some were given to me specifically for the purpose of reviewing them. I resell or can earn commissions from the sale of some of these items. Links within these pages may be affiliate links that pay me for referring you to them. That's mostly insignificant amounts of money; whenever it is not I have made my relationship plain. I also may own stock in companies mentioned here. If you have any question, please do feel free to contact me.

Specific links that take you to pages that allow you to purchase the item I reviewed are very likely to pay me a commission. Many of the books I review were given to me by the publishers specifically for the purpose of writing a review. These gifts and referral fees do not affect my opinions; I often give bad reviews anyway.

We use Google third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.