topic Re: swap utilization in Operating System - HP-UX

swap utilization

kholikt — Thu, 22 May 2003 01:52:22 GMT

I am a bit confused about the swapinfo -tam output.

Here is the swapinfo -tam from one of my L class server.

Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1024 970 54 95% 0 - 1 /dev/vg00/lvol2
dev 4000 1192 2808 30% 0 - 1 /dev/vg00/lvswap
dev 20000 1214 18786 6% 0 - 1 /dev/vg01/lvswap
reserve - 20854 -20854
memory 3963 568 3395 14%

Am I right that the total number of swap available is equal to
(total number of swap + memory) - (total number of used + total number of reserve) = free swap

Re: swap utilization

malay boy — Thu, 22 May 2003 02:03:01 GMT

Hi,
In you case your free swap is (54+2808+18786).And it's nothing to do with your memory.Swap are used went system are running out of physical memory.The senario is when system run out of memory but need to insert something new in memory , the Less recently used spot/data in memory will be swap out from memory to the SWAP space.This is virtual memory kind of story.

hope this help.

regards
mB

Re: swap utilization

Steven E. Protter — Thu, 22 May 2003 02:07:23 GMT

Yes sir,

roughly available memory is equal to physical memory plus swap thats activated.

In your case approximately 30 Gig 4 Gig of which is fast memory.

Thats a lot of swap.

If you ever utilize that much your system will be so slow it drives you crazy.

You might want to at least make the first area, which is mostly used priority 0 and the other two areas priority 1 so they only get used in real heavy times.

SEP

Re: swap utilization

T G Manikandan — Thu, 22 May 2003 03:09:58 GMT

you are right with the equation but one thing to note is that only if pseudo_swap is enabled only then the last field "memory" will add on to the total swap.

Looking at your output.There are processes heavily using up the swap.
Too much swap on the machine.
I doubt the performance of the system would be heavily hampered by this situation.Definitely it requires addition of plenty of RAM.
By the way what is running on this server?

REvert