topic Re: page in in Operating System - HP-UX

page in

navin — Mon, 04 Aug 2008 18:37:57 GMT

If the server starts page in and out , does that mean the physical memory is being over used..i have a situvation where swap can not be increased as the root disk is smaller size. But because of the page in ..and other memory issues - the memory is going to increased.If so what happens if he swap kept as it is instead of increase it accordingly
please advice

Re: page in

Tim Nelson — Mon, 04 Aug 2008 18:41:41 GMT

If you run out of RAM and space to swap out current processes then new processes will fail with cannot fork or not enough space.

Post some swapinfo -tam

Also, if you need to increase secondary swap space it does NOT have to be in vg00. It can be in any vg and on any disk.

page in = a process started
page out = could be that a process has ended
deactivations = a process was deactivated and sent to device swap.

Glance is a great tool for monitoring this.

Re: page in

Patrick Wallek — Mon, 04 Aug 2008 19:00:05 GMT

Swap space does not have to be on the root disk. You can always add additional swap in another VG that has space available.

The 'pi' number really doesn't matter. That is just indicative of processes starting.

The 'po' number is what you want to keep an eye on. If the 'po' column in vmstat is greater than 10, then you have reason to worry and should add more RAM.

Re: page in

James R. Ferguson — Mon, 04 Aug 2008 19:12:32 GMT

Hi:

Actual paging I/O (or swapping in the old terminology) is never desirable. Page-out activity can be seen in the 'po' column of 'vmstat'. This column reflects of memory pressure. Page-out values in dougle-digits indicate serious performanace degradation.

Swap space is also used for process reservatation too, and that's both normal and acceptable. Every process started must reserve swap space should it ever be paged-out. Hence, you may indeed see swap utilization (with 'swapinfo' without any actual I/O.

Whether or not your device swap space resides on vg00 as primary swap space; or on vg00 as both primary and secondary swap space in two or more logical volumes; or as multiple secondary swap spaces on multiple volume groups; is immaterial. It is common to have a relatively small primary swap space (say half of your physical memory) which, by definition, resides on your boot disk, and then have one or more equal or larger secondary device swap pools.

Regards!

...JRF...

Re: page in

Steven E. Protter — Mon, 04 Aug 2008 19:14:48 GMT

Shalom,

Actual paging needs to be fixed either be increasing the supply of memory or reducing the demand. Buffer pool can be reduced. Oracle SGA can be reduced but in general, I find adding memory is better for all concerned.

SEP

Re: page in

Venkatesh BL — Tue, 05 Aug 2008 02:57:23 GMT

Yes, look at the current values of your kernel tunables. If they require further tuning, do it. Else, adding more RAM would be the best option.