Re: Available free memory in SUN

In article <D7uG4.12263$TM.769368_at_bgtnsc06-news.ops.worldnet.att.net>, "Ben Kim" <kimben_at_worldnet.att.net> wrote:

>I maintain Oracle(8.0.5.1) on SUN(2.6) with 6 G of memory. When I checked
>free memory using
>top or vmstat in UNIX, I saw free memory down to approximately 100M when
>sort_area_size is
>only 64K and about 120 users connected to the database. I don't believe
>we
>are using 5.9G when
>our SGA is about 800M. Or are we really using 5.9G of free memory? The

Sun's website has a good article on how Solaris manages memory:

http://www.sun.com/solutions/third-party/global/SAS/pdf/vmsizing.pdf

I generally watch our swap partition with 'iostat' to make sure that we aren't paging to disk (or at least aren't doing it too much) and 'vmstat' to watch things like the page scan rate.

I've been told that the system tries to keep at least 4,000 Kbytes on the free list (normally the fifth column in vmstat). As long as you are above that, the system really won't be working too hard to find RAM. This seems to be a decent rule of thumb, although doesn't really give a specific judgement as to how much RAM you need and I'm not sure how it applies to systems running stuff like Oracle.

Also look into sar (and sag), it can give you a better picture of how the system loads vary during the day.

drouse Received on Thu Apr 06 2000 - 00:00:00 CDT