topic Re: paging in Operating System - HP-UX

paging

Indrajit Bhagat — Wed, 29 Aug 2007 04:26:17 GMT

Event Msg The percentage of paging space in use (Current PS usage : 10.50 %, Pages out : NA) is too high.
helptext: "The paging space usage on the server is greater than the specified threshold."
cause_and_effect: "Server is using excessive amounts of paging space. This should be investigated and resolved to prevent any further problems with system."
suggested_action:

how can i resolve this issue.

Re: paging

Steven E. Protter — Wed, 29 Aug 2007 05:03:06 GMT

Shalom,

Two ways:

1) Buy and install more memory.
2) Reduce memory use.

Common problems with recommendation #2 include oracle dba settings that are set too high. drop dbc_max_pct to 7 and dbc_min_pct to 5 in order to reduce memory consumption by the buffer cache. A very good idea to do this concerning Oracle.

SEP

Re: paging

Bill Hassell — Wed, 29 Aug 2007 05:27:54 GMT

Just by itself, the measurement is not meaningful. Run the command:

swapinfo -tam

and see how much space is actually being used in your swap areas. That still isn't enough though. You may have dozens or hundreds of processes that sleep for long periods of time, perhaps waiting for a person to answer a question. If you are short of RAM, these long wait processes may be paged out to the swap areas. The only meaningful metric is PAGE OUT which is found with vmstat. Look at the po column during the busiest periods. Is the number 0-9? Then all is well and there are no significant delays incurred by lack of RAM.

If the number is 2 digits (ie 10-99) and stays at this level for minutes to hours, then you are short on RAM and it is beginning to impact performance. Sustained numbers more than 100 indicate a severe shortage of RAM. Now if performance (speed) of the system is no concern, then I would not worry about it. Just make sure you have enough swap space.

But if performance is very important, you must double of triple the amount of RAM. As mentioned above, you can reduce the memory requirements for your applications such as Oracle but that will also reduce performance.

Re: paging

Basheer_2 — Wed, 29 Aug 2007 09:46:52 GMT

Hi Indrajit,

Post the results of

swapinfo -tam
vmstat 5 9
kmtune or kctune

What apps you are running