RE: SGA/PGA question
- From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>
- To: "Harvinder Singh" <Harvinder.Singh@xxxxxxxxxxxxx>, "ORACLE-L" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 25 Aug 2006 17:00:44 -0400
You can use the pmap command on Solaris to see exactly how the memory
usage of a process breaks down.
Do:
pmap -x <pid of server process>
Consider that all server processes will show the SGA shared memory
segments as part of the server process address space, but that does NOT
mean that each process has that much memory allocated, that's the whole
point of shared memory. So, look at the output of 'pmap' and don't
count the lines that indicate "shared" and that will give you an idea of
how much memory is being consumed by each server process. To get an
idea of system wide memory consumption, consider that you should start
with the amount of allocated shared memory, and then sum all the
non-shared memory listed from pmap for all processes on the box.
Careful not to double count the shared memory.
Also, particularly on a box with such memory shortage, don't be stingy
w/ swap. Make you have swap AT LEAST 2x your total physical memory.
Try the 'swap' command with the '-l' and '-s' options, check the man
page for explantions of their outputs.
Hope that helps,
-Mark
--
Mark J. Bobak
Senior Oracle Architect
ProQuest Information & Learning
Ours is the age that is proud of machines that can think and suspicious
of men who try to. --H. Mumford Jones, 1892-1980
-----Original Message-----
From: Harvinder Singh [mailto:Harvinder.Singh@xxxxxxxxxxxxx]
Sent: Friday, August 25, 2006 4:49 PM
To: Bobak, Mark; ORACLE-L
Subject: RE: SGA/PGA question
What are the commands to check the memory usage by each process on sun
box, since sga is 600gb and pga 200gb and still we are seeing 0 free ram
left so there must be other processes to check before I can change and
of this parameters. I completely agree that we need bigger machine but
still I need to solve this issue for 2-3 weeks.
Regards
--Harvinder
-----Original Message-----
From: Bobak, Mark [mailto:Mark.Bobak@xxxxxxxxxxxxxxx]
Sent: Friday, August 25, 2006 4:40 PM
To: Harvinder Singh; ORACLE-L
Subject: RE: SGA/PGA question
Hi Harvinder,
First off, there is no pga_target parameter. I'll assume you're
referring to pga_aggregate_target. With it set to 200MB and expecting
900 dedicated server processes connecting concurrently, that's about
233017 bytes per server process for pga memory. That's WAY too small.
Assuming that you have 2GB RAM, and you're ok w/ the 600MB you've
allocated to sga_target, well, perhaps you could try bumping
pga_aggregate_target to 900MB. But, even there, you're only at 1MB per
server process. Unless you have VERY MODEST memory usage requirements,
that's not going to be enough.
You need a box with more memory. Shared server (aka MTS) is not a
panacea.
Also, are you using raw devices? If you're on cooked filesystems, are
you using direct I/O? If not, the OS will use memory to cache your
datafiles in the filesystem layer, and consume memory there too.
Bottom line, you need more memory....
-Mark
--
Mark J. Bobak
Senior Oracle Architect
ProQuest Information & Learning
Ours is the age that is proud of machines that can think and suspicious
of men who try to. --H. Mumford Jones, 1892-1980
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Harvinder Singh
Sent: Friday, August 25, 2006 4:24 PM
To: ORACLE-L
Subject: SGA/PGA question
Hi,
We have 10.1.0.3 installed on sun solaris 10 having 2GB RAM and 2GB swap
file. In our system 4-5 application starts at same time and each
requires about 180 connections to the database. So about 900~ processes
can be connected at the same time and we have set the following
parameters:
Processes = 1000
Pga_target = 200MB
SGA_TARGET = 600MB
We are using the dedicated server model and getting following error
frequently and also notice that physical RAM drops to 0 MB free:
Ora-12500 (unable to start the dedicated process)
Since this is just a development box, so to fix this issue we are
planning to move to MTS model.
Is there any other way to solve this issue, if we have to go to the MTS
model what should be the value of PGA and SGA to be set?
Thanks
--Harvinder
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