UNIX for Advanced & Expert Users

This is a fairly basic advanced question!

Does anyone happen to know what level of page faults should be acceptable on a fully operational production system?

Useful (?) information:

Production system using Oracle database
Compaq Tru64 UNIX Server (not sure what model, but it's big!)
8 CPU's
8 Gig of RAM - 99% is used
27 Gig of swap space - 35% is used
1050 processes
Kernel takes up 350Mb

The average Page Fault level is around 25000 per minute - this was achieved by doing a vmstat 60

Questions are :

Is this too high?
What should be an appropriate level of page faults?

Many thanks in advance (and apologies if the question has been asked a thousand times before - I did check the FAQ's)

Neil Weston

What version of the OS?

You will have to understand even with knowing what version of OS you are running, it would be impossible to give a good answer to your question. If a system is paging it may be just fine. Normally if a system is swapping, you have problems. But sometimes paging can also cause problems. You really need to get a history of how the system has acted in the pass, how many users are on it (including the ones you can not see ie. Oracle database clients).

To get your version -
Here are three commands that will display the version of UNIX that is running.

1. #dia -R -i osf_entry=300 |grep "Digital UNIX V"
2. #uerf -R -r 300 |grep "Digital UNIX V"
3. #sizer -v

And then go to the following links, especially the second (if it matches your version it would be more helpful but it will give you the different things you need to look at to find out if you really have a problem or not. )
Try info found in http://www.tru64unix.compaq.com/docs/
and http://www.tru64unix.compaq.com/docs...M_BP/TITLE.HTM

Hope this was helpful.

Another consideration is "What else is running?".

Do you also have Tuxedo running on the same box?
Many variables to consider.
But you should be able to get more detail from your Compaq rep.

BOL

Thanks for you replies!

I've had a look at all the TRU64 documentation, but as the system is a greenfield site, I've got no past stats to go back to for comparisons.

Unfortunately the documentation only goes into tuning, so far I can't find anything about expected page fault levels, and implications of high levels. Still looking!

Our application is the only one that is running and it's thick server; thin client. There's not a lot of memory usage that we can reduce at present - although it's being looked at.

Thanks once again

Neil

It would be helpful if you could describe your swap configuration..... is your system thrashing due to swap problem? How large is your swap space? How much of the swap space is being used?

Thanks for you reply, Neo.

The problem is that we have individual users that are sometimes getting response times that are many times slower than usual. This is usually limited to single users rather than for everyone at once. One thing I've experienced in the past is that when NT systems are paging heavily and performance suffers, the numbers of page faults is high. Unfortunately I've got no way of determining what high is for this Compaq server, and I'm trying to prove / disprove that memory or paging is the cause of the problems.

The page file size is 27 Gig located across a number of spindles. There is 35% of this being used. I did mention this in my first post, so if you meant something else, please let me know and I'll get back to you as soon as I can.

Neil