Re: Free memory in Solaris

From: thiru <tmgn_at_excite.com>
Date: Mon, 21 Jun 1999 14:06:23 -0400
Message-ID: <376E7F1F.FA083C66@excite.com>

Hi Bass,
You are absolutely right. I too got tired of finding an easy way to find out Free memory on Solaris. vmstat or sar does not tell you this. Looks like Solaris Uses up almost every byte of Physical memory you add on, without actaully consuming it.

However you can track Page Faults/sec( pi,po,fr) columns in Vmstat to determine if your system is Paging excessively and wants more Physical memory. If  'fr' (pages freed) steadily declines then the System needs more memory ,if I am right.

Also Swapping should be Zero.

Hope this helps U , a little bit.
-Thiru
 

Bass Chorng wrote:

I am trying to find out how much physical memory is left
after I size my SGA in Solaris. This should be a very
basic and simple question. But it almost turns into a
nightmare.

I know the answer is NOT vmstat - if thats what you are
thinking. It is NOT that simple with Solaris. It IS that
simple with HP-UX, that vmstat shows free lists of memory.
You can multiple your free lists by 4K and get the free
memory in bytes.

I have checked various webs, even with Sun support. There
simply has no straight answers. Basically you need 3rd party
tools. ( I have no idea what vmstat tells you then, to be honest ).
I know man page with vmstat is either wrong or misleading.
I says the column free tells you free mem in bytes, then
a book I read says it tells you free mem in pages - but
neither one matches reality. They are both way off.

Then I read a white paper on Sun Support, it says, it is not
easy....etc, and it never gives you a clear answer.
I can hardly believe this.

So, there must be trillions of DBAs out there sizing memories
in Solaris everyday. How do you guys detemine how much free
( physical ) memory is left on a system? Don't you size
stuff like sort_area_size AFTER knowing how much you have free ?

I hope I am completely wrong, because this question seems to
be too simple and easy to be answerless. So I am seeking help
from the largest pool of Oracle expertises out there - please
share your experience if you know how. I would certainly
appreciate your help.

-Bass Chorng
 DBA
 Lucent Technologies.

Received on Mon Jun 21 1999 - 13:06:23 CDT