High paging activity

malru · 06-16-2006, 01:43 AM

Hi,

I'm working with a 9i RAC database with two nodes,in one
node(having 8 CPUs),paging activity is very high(reason is due to ORACLE process only) it goes to 80%,but in
another node there is no high paging activity,system admin people says the server will go down if it reaches 90%.What can i do to avoid high paging activity?

Note:
When the database is down,paging activity is normal,but only when the database is up,the paging activity is increased.

Thanks,
Malru

nukkel · 06-16-2006, 09:38 AM

Quote:

Originally Posted by malru

What can i do to avoid high paging activity?

Add more main memory.

--n

crabboy · 06-17-2006, 09:36 PM

Or reduce the size of the Oracle cache.

JurgyMan · 06-19-2006, 09:46 AM

modern databases will cache their own file IO...
AIX by default also wants to use a bunch of ram for FILE IO
caching... and so you waste lots of ram by double caching.

Check the values for vmo minperm and maxperm (defaults are 20/80)
I usually lower drastically via:
vmo -p -o minperm%=5 -o maxperm%=20 -o maxclient%=20

Frustin · 06-19-2006, 09:52 AM

also mount your filesystems using dio (direct I/O):

Code:

/oracle:
        dev             = /dev/lvoradata
        vfs             = jfs
        log             = /dev/loglv00
        mount           = true
        options         = dio,rw
        account         = false

Here is a link to a PDF that will tell you all about it.

crabboy · 06-19-2006, 10:01 AM

http://www-128.ibm.com/developerwork.../DirectIO.html

JurgyMan · 06-19-2006, 10:01 AM

Actually, if this is a modern RAC implementation, it'd probably be better off using Concurrent IO instead of Direct IO...

http://oracle.ittoolbox.com/white-pa...urrent-io-2582

crabboy · 06-19-2006, 10:47 AM

Ahh, we actually use both the old and new. Good to know.