swapinfo interpretation

[Jon H]

# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 8192 2762 5430 34% 0 - 1 /dev/vg00/lvol2
reserve - 5428 -5428
memory 8190 3333 4857 41%
total 16382 11523 4859 70% - 0 -

I know swapping is bad and we should add memory or tune to fix. We are looking at this but in the mean time I would like a better understanding of the output here.
11.23 PA-RISC system - Oracle database etc..

So when I dev free it shows 5430 and reserve should 5428 used. Are these directly related like I believe they are? ie. would reserve ever be greater than dev total free? I believe we need to add more dev swap to at least equal RAM but I need to build a case for this.

additional glance output

B3692A Glance C.04.70.000 08:17:40 boxname 9000/800 Current Avg High
--------------------------------------------------------------------------------
CPU Util SU | 5% 5% 5%
Disk Util F FV | 14% 14% 14%
Mem Util S SU UB B | 96% 96% 96%
Swap Util U UR R | 71% 71% 71%

any help is appreciated - and points will be forth coming...

[Dennis Handly]

>ie. would reserve ever be greater than dev total free?

No. Reserve can be greater than Dev used.

>I believe we need to add more dev swap to at least equal RAM

It depends, it currently equals memory, 8 Gb. You have 4 Gb free. Are you planning to add more of a load on your system?

[John Guster]

normally device swap size is at least equal that of RAM. What is your RAM size? (In glance, m will show you RAM size: Phys Mem)

[Jon H]

Glance shows 8GB for Phys Mem so I guess that memory line is = RAM now.. well back to the drawing board...
thanks for all the help.

[Jon H]

close

[John Guster]

in swapinfo -tam output, memory is about 75% of RAM called pseudo swap space, it is not your RAM size. It seems you have more than 8GB RAM, your device swap is 8GB. You should increase your device swap to 2X RAM. It can be done while system is online. Once swap space is 2X RAM, it should improve your performance.

[Dennis Handly]

>John: Once swap space is 2X RAM, it should improve your performance.

Adding swap will not improve performance. All it will do is allow your applications to run, instead of abort. But you may consider that an improvement. ;-)