RE: SGA/PGA question

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

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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_at_MetraTech.com] 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_at_il.proquest.com] 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_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] 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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http://www.freelists.org/webpage/oracle-l

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http://www.freelists.org/webpage/oracle-l Received on Fri Aug 25 2006 - 16:00:44 CDT