Solaris

here is the thing :

# prtmem - is a part of memtool and that is not recomended to run on prod i guess

#netstat -kp | grep pp_kernel
For me there is no option as - k in netstat on solaris 10

#mdb -k

I really dont have any idea about this dubugger but i will chk it out ..

Tell me this thoguh what sar -k shows in my case .. didnt that meant that kernel is using so much memory ?

That is a very old rule of thumb which I no longer agree with. Memory is so cheap and plentiful these days that you should hardly ever require swap, if you do it is a sign of problems. I generally don't ever configure more than 4GB of swap, even on a 64+GB system.

In fact, if your physical memory is alot, of course Im not asking you to give 128 GB for your swap. But you will t least need 16Gb of swap for a 64 0r 128 configuration minimally.

This is the architecture of Solaris. You will need additional swap for your paging and the space for your coredump(which might be Huge in size). You won't want your system to crash further after a system panic, would you?

incredible - of course your dump could be rather large but i run m9000's and have never seen a core file greater then a few gigs tops. we are talking about 1-4 TBs of memory and 64 sparc64 VI (128 cores) processors.

For your info M series is a collaboration of Fujitsu with SUN and their architectures do differ.. Though you may find M9000 is working like a 6900 system..
If its gonna be a "SUN" mid-range or highend servers, what I say still makes sense.

Yes, I agree with this. The old 2 pounds of swap for every pound of memory was back in the old days when memory was expensive and it was cheaper to use disk swap.

If you have 7 GB of RAM, something is really wrong if you need 14GB of swap.

4GB of swap is more than enough, good post Annihilannic. Thanks.

There is a lot of infomation in this thread which is not valid. Almost everything Incredible has stated in this thread is incorrect in terms both of system configurations and reasons for choosing swap size.

A few points worth note.
In summary you can get by to some extent if you don't have enough memory by adding swap, but it will hurt performance. Ideally you should have enough memory to run all your applications in memory, and the general rule of thumb nowadays is about 30% of memory for swap but there are more detailed reccomendations in the Solaris documentation.

Jim Laurent at Sun wrote a blog on this topic about a year ago, which you could look up.

EDIT: Found the blog:Solaris FAQ: Myths and facts about Solaris swap space : Jim Laurent's Weblog