Re: Available free memory in SUN

Martin Hepworth (maxsec_at_totalise.co.uk) wrote:
: Ben Kim wrote:
: >
: > All,
: >
: > 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
: > database is OLTP
: > server. Sometimes, I saw free memory up to 4G when 120 users are connected.
: > But I believe
: > these are idle users.
: > Any ideas as why we are using so much memory?
: >
: > THANK YOU!!
 
: HI
: 'free memory' (RAM actually) is used by SOlaris as file cache, so its a
: bit more fun to get actual free RAM on solaris.
 

: proctool (from www.sunfreeware.com) can help. and theres some stuff on
: www.sunworld.com that descibes how things work and calculating usages
: etc.

The 'Free memory' reported on Solaris is actually the current amount of WASTED memory. Solaris tries to use all of the memory pool for disk cache and frees it to programs dynamically. You should be more worried if you have plenty of 'free memory' because this means that Solaris is probably not optimising the memory pool correctly.

This disk caching is making a big improvement to your system performance.

Rather look at the amount of swap in use, this is a better indicator of if you have enough physical memory.

( ISTR that memory usage reporting has been changed in Solaris 8, so   my comments refer to Solaris 7 and earlier ) Received on Thu Apr 06 2000 - 00:00:00 CDT