regarding physical memory and swap

[masthan_1]

Hi,
In a server rx4640, the total physical memory would be 32756MB and now the free memory is 5528MB(Page Size: 4096 bytes). Pls also find the swapinfo output below.
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 49152 0 49150 0% 0 - 1 /dev/vg00/lvol2
dev 15040 0 15039 0% 0 - 1 /dev/vg00/lvol9
reserve - 9965 -9965
memory 32739 6523 26216 20%
total 96931 16488 80440 17% - 0 -

and i just want to know, at what situation the lvol2 and lvol9 would be used. what is the page size, where it counts?
if additional we can learn from this kind of output, pls let me know what are those? Concerning this details, what action i have to take to avoid memory max usage?

[SoorajCleris]

Hi ,

lvol2 and lvol9 , will be used when paging/swaping starts.

currently your system doestn have memeory pressure, and no applications are configure for using swap.

In this case , paging and swaping will happen depend on the kernal parameter .

minfree, lotsfree and desfree.


Regards,
SOoraj

[SoorajCleris]

Hi ,

what we can learn from this output.

Take the output at the time of max system load ( some intervals).

Check the output and verify if there any memory pressure. If your memory usage is 95 percent and there is no pageouts.. your system is running fine.

If you have enough memeory you can enable pseudo swap also.

Regards,
Sooraj

[Dennis Handly]

>Sooraj: If you have enough memory you can enable pseudo swap also.

11.31 has it always on, so you should always enable pseudo swap on previous versions.
And 32 Gb is "enough" memory. :-)

[SoorajCleris]

Ha ha .. :) you are right... Thanks Dennis,

I read this (the below) long back, and I liked the way he said..


If there is no device or filesystem swap; the system uses pseudo-swap as a last resort. Pseudo-swap is never reserved; it is either free or pseudo-allocated. In reality, we never swap to a pseudo-swap device, because it's in memory. If we utilize pseudo-swap, we need to appreciate that it is simply a mechanism for fooling the virtual memory system into thinking we have more swap space than we actually have. It was designed with large memory systems in mind, where it is unlikely we will ever need to actually use swap space, but we do need to configure some swap space.

[Michael Steele_2]

http://docs.hp.com/en/1219/tuningwp.html

a) you're only using 20% of physical memory
memory 32739 6523 26216 20%

b) you're using none of swap.

c) you don't need lvol9 and should recapture it.