SGA_MAX_SIZE & SGA_TARGET

If anyone can explain to me the relationship of these 2 parameters? Chapter 8 Database Concepts doesn't clearly define how and if they are used in tandem.
Matt

Let me simplify it a bit ...
From the links I provided:
SGA_MAX_SIZE has a default. Therefore it does not need to be set.
SGA_TARGET has a default. it does not need to be set. The default is 0, meaning NOTHING is automatically handled.
In the Reference manual description for SGA_TARGET, it provides a link to the Concepts manual. That link is there to provide more detailed information, so we follow it ...
The SGA_MAX_SIZE and SGA_TARGET are in the table of contents of the Concepts manual. Following that, we find
It is significant that SGA_TARGET includes the entire memory for the SGA, in contrast to earlier releases in which memory for the internal and fixed SGA was added to the sum of the configured SGA memory parameters. Thus, SGA_TARGET gives you precise control over the size of the shared memory region allocated by the database. If SGA_TARGET is set to a value greater than SGA_MAX_SIZE at startup, then the latter is bumped up to accommodate SGA_TARGET.
Note:
Do not dynamically set or unset the SGA_TARGET parameter. This should be set only at startup.
There is a lot of additional supporting information in the Concepts manual as well.
Message was edited by: Hans Forbrich
Corrected the interpretation of SGA_TARGET default.

Similar Messages

SGA_MAX_size, SGA_target, PROCESSES Parameters

hi
i have oracle 11g and i want to know what are the uses of these parameters
SGA_MAX_size
SGA_target
PROCESSesAnd how can i change its values ?
If any onne of u has any information about these things please help me
Regards ,

From charles Hooper;
Take a look at page 21 of the Platform Guide for 10g Release 2 (10.2) for Microsoft Windows (32-Bit):
http://download.oracle.com/docs/cd/B19306_01/win.102/b14304.pdf
Each dedicated session's connection to the database on the Windows platform requires at least 1MB of memory - just for the session to connect. With 250 sessions connected, 250MB of memory is required before the sessions even submit their first SQL statement to perform useful work. On 32 bit Windows, each process is limited by default to no more than 2GB of memory - once the 2GB memory limit is reached, the listener will no longer be able to hand off connection requests. It is possible to raise the 2GB limit to just short of 3GB through a change to the server's boot.ini file, but that still does not allow the server to use more than 4GB of memory (and each process cannot use more than roughly 3GB).
Note that you are using the SGA_TARGET. SGA_TARGET cannot be used when USE_INDIRECT_DATA_BUFFERS=TRUE, which will allow Oracle to relocate the database block buffers into the memory region above the 4GB memory mark.
Charles Hooper
Co-author of "Expert Oracle Practices: Oracle Database Administration from the Oak Table"
http://hoopercharles.wordpress.com/
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.

Oracle Parameter (SGA_MAX_SIZE / SGA_TARGET)

Hello together,
since yesterday we have a new oracle database on X64 (64BIT on Windows) with SAP R/3 4.7.
The server have 24GB ram and 2x quad Core CPU.
How can give me a good value for this parameters (for oracle)
SGA_MAX_SIZE
SGA_TARGET
I don't know what is a good size for such a hugh physikal memory!
Thank you
Christian

Hello Christian,
the parameter SGA_TARGET is "not longer" supported by SAP.
Take a look at sapnote #828268
At the beginning of oracle 10g we have activated the ASMM ... but there is still a bug with oracle 10g which results in a hang situation (solved in 11g ... no backport planned)
For more information regarding to the bug... take a look at bugnotes on metalink 4466399/4472338
SGA_MAX_SIZE should be a little bit higher than the sum of all your memory pools (SGA), because of you can extend some areas dynamically on the fly (if you are using a spfile).
Regards
Stefan

Cahnge sga_target & sga_max_size ?

Dear Friends ,
I want to change the value of sga_max_size , sga_target using "ALTER SYSTEM SET .... scope=spfile " command in my production database server .
Now I need the suggestion which one I need to change First , sga_max_size or the sga_target ?
I want to set ,
sga_target = 15000 M and sga_max_size = 18000 M
Can u plz advice me ?
my another query ,
For the 15000 M sga_target size , what is the recommended size for the PGA , i.e., which value I need to set for the PGA for the value of "sga_target = 1500 M " .
advice me plz ...........
Edited by: shipon_97 on Nov 11, 2008 8:09 PM

>
As mentioned, if you only change spfile value, the order doesn't matter. But to be on the safe side, change sga_max_size first.
Because if you forget to change sga_max_size after your increase sga_target beyond it, your instance can't startup nexttime. You will have to recreate a spfile because you can't edit spfile.
>
For the 15000 M sga_target size , what is the recommended size for the PGA , i.e., which value I need to set for the PGA for the value of "sga_target = 1500 M " .
advice me plz ...........
PGA setting is not directly related to SGA size.
Check Oracle performance tunning guide,
Setting PGA_AGGREGATE_TARGET Initially
Monitoring the Performance of the Automatic PGA Memory Management
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/memory.htm#i47856

Advice on sga_target and sga_max_size

hi,
a little abt my existing system
HP UX 11.11 oracle 10.2.0.4 EBS11.5.10
memory 4GB
SGA 2 GB
i will be increasing physical emory to 20GB today
i need advice on setting sga_target and sga_max_size
currently my SGA_MAX_SIZE=2GB

If you are increasing the physical memory then set the SGA_MAX_SIZE to max estimated size based on application usage and keep the SGA_TARGET to whatever value you have currently.
This helps to increase SGA dynamically (SGA_TARGET) when ever application needs and you no need to shutdown your database.
It is always advised to keep SGA_MAX_SIZE > SGA_TARGET.
Hope this helps.
Regards.
Satishbabu Gunukula
http://oracleracexpert.blogspot.com
[Click here to learn Install and Configure ASM in 10g|http://oracleracexpert.blogspot.com/2009/08/install-and-configure-asmlib-in-10g.html]
Edited by: Satishbabu Gunukula on Aug 21, 2009 12:20 PM

Setting sga_max_size and memory_target

what happens when i set
sga_max_size = 4500
memory_target = 5000M
memory_max_target=5000M
sga_target=0
can / will oracle use more than 4.5GB for sga ?
can pga grow more than 500M ?
startup;
ORACLE instance started.
Total System Global Area 4710043648 bytes
Fixed Size 2234376 bytes
Variable Size 3925870584 bytes
Database Buffers 771751936 bytes
Redo Buffers 10186752 byt

user9198889 wrote:
g777 wrote:
hi
DB and OS version would be nice to see...
look here
http://www.dba-oracle.com/oracle11g/oracle_11g_memory_target_parameter.htm
SGA_MAX_SIZE & SGA_TARGET
linux 5.5
db 11.2.0.2 rac GI 11.2.0.2thanks for the links,
"When using AMM (by setting memory_target, and/or sga_target, the values for the “traditional” pool parameters (db_cache_size, shared_pool_size, &c) are not ignored. Rather, they will specify the minimum size that Oracle will always maintain for each sub-area in the SGA.
so that means PGA wont grow more than 500MB and SGA be set to minimum of 4.5GB?
actually if you carefully read the above comment it doesnt mentiond sga_max_size it only says traditional pools such as db_cache_size etc...
does this also include sga_max_size?
I had a look at the other link to a thread but the question is slightly diffrent, they are discussing relation of sga_target to memory_target, I am intrested to know about sga_nax_size inrelation to memory_target

SGA_MAX_SIZE and swap

Hello,
When I read Doc 778777.1, I found it said: "On most OSs(except solaris) if you specify SGA_MAX_SIZE, then the complete size of SGA_MAX_SIZE is reserved from Swap at instance startup, not from physical RAM." I want to konw why SGA_MAX_SIZE is reserved from Swap? I always thought it was reserved from physical RAM.
Thanks.

Even I am not much clear so could be wrong ;) [See note 761960.1 also]
What i can make out from above 2 notes is that Oracle doesn't want to waste physical memory for additional memory requirement above SGA_TARGET (ie SGA_MAX_SIZE - SGA_TARGET).

Reduced SGA_TARGET, but SGA size not changing?

I reduced the sga_taget from 1536M to 512M:
alter system set sga_target = 500M scope = memory;
System altered.
select VERSION from v$instance;
VERSION
10.2.0.3.0
show parameter sga
NAME TYPE VALUE
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 1536M
sga_target big integer 512M
But the real memory still showing the original value
show sga
Total System Global Area 1610612736 bytes
Fixed Size 2030456 bytes
Variable Size 1509950600 bytes
Database Buffers 83886080 bytes
Redo Buffers 14745600 bytes
why is that while it's a dynamic parameter?
Thanks a lot for any help.
Edited by: user10484253 on May 13, 2011 8:36 AM
Edited by: user10484253 on May 13, 2011 8:39 AM
Edited by: user10484253 on May 13, 2011 8:41 AM

I would suggest you to check v$sgastat to find out the exact SGA memory you are using currently instead of using "SHOW SGA" when when you set SGA_MAX_SIZE & SGA_TARGET initialization parameters.
Below is a sample output from one of my test dbs. As you can see below my SGA size is only 1GB.
SHOW SGA shows 2GB thats because I have set SGA_MAX_SIZE to 2gb ( which only means that I can grow my sga up till 2 gig , it may not be my current sga size).
you can try increasing or decreasing SGA_TARGET and check memory usage on OS level to see the difference.
SQL>show parameter sga
NAME                                 TYPE        VALUE
lock_sga                             boolean     FALSE
pre_page_sga                         boolean     FALSE
sga_max_size                         big integer 2000M
sga_target                           big integer 1008M
SQL>show sga
Total System Global Area 2087780352 bytes
Fixed Size                  2155336 bytes
Variable Size            1744833720 bytes
Database Buffers          318767104 bytes
Redo Buffers               22024192 bytes
SQL>select name, round(sum(mb),1) mb
2        from (
3      select case when name = 'buffer_cache' then 'db_cache_size'
4                  when name = 'log_buffer'   then 'log_buffer'
5                  else pool
6              end name,
7              bytes/1024/1024 mb
8                   from v$sgastat
9           )group by name
10 /
NAME                  MB
db_cache_size        304
java pool            128
large pool            16
log_buffer            21
shared pool          528
                     2.1
6 rows selected.
SQL> -- V$SGA_DYNAMIC_FREE_MEMORY: Information about the amount of SGA memory available for future dynamic SGA resize operations.
SQL>select * from V$SGA_DYNAMIC_FREE_MEMORY;
CURRENT_SIZE
1040187392- Krishna

(10g)SGA_TARGET 파라미터를 이용한 AUTOMATIC MANAGMENT SGA COMPONENTS

제품 : ORACLE SERVER
작성날짜 : 2004-04-26
PURPOSE
이 문서는 SGA_TARGET 이라는 새로운 파라미터를 이용하여 Automatic
management SGA Components에 대하여 알아보기로 한다.
Explanation
SGA_TARGET 파라미터를 이용한 Automatic management SGA Components에 대하여
설명하기로 한다.
Automatic management SGA Components using SGA_TARGET
Oracle 10g부터 다음과 같은 각각의 SGA component에 대한 값들을 manual하게
설정할 필요가 없다.
shared_pool_size
log_buffer
java_pool_size
large_pool_size
buffer_cache_size
위 SGA 파라미터들의 사이즈를 측정하고 initSID.ora file에 그 값을 설정할
필요가 없음을 의미한다. 사실 SGA 크기를 정의하는 위 파라미터들을 설정하지
않아도 된다.
다만 10g 에서는 SGA_TARGET 이라는 새로운 파라미터만 셋팅하면 된다.
SGA_TARGET 이라는 파라미터는 해당 instance에 필요한 SGA의 최대 크기를
가리킨다.
SGA_TARGET을 152M 로 잡았다고 가정하자. 이것은 SGA가 커질 수 있는 최대 크기가
152M 라는 의미이다. Shared pool, buffer cache, large pool, java pool 과 같은
SGA component들은 이 maximum 사이즈 내에서 할당될 것이다.
오라클은 이러한 component들의 초기 값을 자동으로 계산하고 필요에 따라
자동으로 resize한다.
즉, SGA_TARGET 만 셋팅되어 있으면 shared pool, buffer cache, large pool,
java pool에 대하여 값을 명확히 지정할 필요가 없다.
Example
SGA_TARGET=152M 로 잡았다고 가정한다.(block size is 8K).
SQL> show parameter sga_target
NAME TYPE VALUE
sga_target big integer 152M
오라클은 다음과 같이 SGA component들의 사이즈를 정의한다.
SQL> show sga
Total System Global Area 159383552 bytes
Fixed Size 769328 bytes
Variable Size 72270544 bytes
Database Buffers 62914560 bytes
Redo Buffers 23429120 bytes
여기서 주목할 점은 다음과 같다.
1) SGA_TARGET을 셋팅하면 SGA_MAX_SIZE 의 값은 또한 SGA_TARGET 으로 셋팅된다.
즉, SGA_TARGET = SGA_MAX_SIZE.
SQL> show parameter sga
NAME TYPE VALUE
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 152M
sga_target big integer 152M
2) SGA_TARGET 의 값을 SGA_MAX_SIZE보다 더 크게 설정할 수 없다.
즉, SGA_TARGET <= SGA_MAX_SIZE.
SQL> alter system set sga_target=160M;
alter system set sga_target=160M
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-00823: Specified value of sga_target greater than sga_max_size
Reference Documents
<Note:256913.1>
Oracle Database Concepts 10g Release 1 (10.1)
Part No. B10743-01
Chapter 8: Memory Architecture

842638 wrote:
hi experts.. please answer the question
Im on 10.2.0 linux....
sga_target=200m
sga_max_size=400m
if automatic components take 180MB out of 200MB and lets say manaul components take 10M. so is the remaing 10MB wasted? yes or noWhy wasted? Only after giving memory to the manual components, whatever is left would be given to the automatic components. So nothing would be wasted by this approach.
HTH
Aman....

Installation fails on Ubuntu 8.04

Hi there,
first I tried downloading the .deb file from Oracle and installing it manually. Installation went fine, but I wasn't able to start the database. After trying different things for a couple of hours I gave up and tried to install it from the repository as [mentioned in the docs|http://www.oracle.com/technology/tech/linux/install/xe-on-kubuntu.html]. The problem is, it does not create /etc/init.d/oracle-xe so I am not able to configure it. Is this a known problem?
Currently I am trying it again with the .deb file from Oracle. The problem here is, when connected with SQL*Plus and typing "startup" I get error.
ORA-27102: out of memory
Linux Error: 28: No space left on device
I don't know what it means. I have about 14G of memory available on harddisk.
The minimum requirements seems to be met as well:
# grep MemTotal /proc/meminfo
MemTotal: 4016352 kB
# grep SwapTotal /proc/meminfo
SwapTotal: 8193140 kB
Please help!
Leonid
Edited by: the[V]oid on 13.04.2009 07:13
Edited by: the[V]oid on 13.04.2009 07:31
Edited by: the[V]oid on 13.04.2009 08:40

For first ubuntu is not a certified platform for oracle installation.
file /etc/init.d/oracle-xe is more needed for automated oracle startup/shutdown if server goes down.
You can live without it or create manually.
Startup issues could be related with Your database memory settings. Look into init.ora/spfile.ora and find out what are settings for sga_max_size, sga_target, pga_aggregate_target.

ORA-27300-1-2 Database on Windows 2003 was hung

Hi all,
Our 11g database running on windows 2003 was hung. We bounced the database and reduced SGA_MAX_SIZE/SGA_TARGET =900M from 1200M. Problem was resolve.
SGA_MAX_SIZE/SGA_TARGET =1200M
PGA_AGGREGATE_TARGET=540M
Can anyone explain meaning of below line in trace file..
Memory (Avail/Total): Ph:1659M/4095M, Ph+PgF:13745M/16166M, VA:43M/2047M
1. Was there only 1659M available on Server for Oracle.exe?
2. Or Oracle.exe was looking for 1659M and could not get that?
3. What is the possiblity adding a /3g switch would have helped (if there was just 1659M free on server for Oracle , how /3g will help)
Errors In Alert log
ORA-27300: OS system dependent operation:CreateThread failed with status: 8
ORA-27301: OS failure message: Not enough storage is available to process this command.
ORA-27302: failure occurred at: sssxcpttcs4
In Trace file
ORA-27300: OS system dependent operation:CreateThread failed with status: 8
ORA-27301: OS failure message: Not enough storage is available to process this command.
ORA-27302: failure occurred at: sssxcpttcs4
OS tid = 10208
Memory (Avail/Total): Ph:1659M/4095M, Ph+PgF:13745M/16166M, VA:43M/2047M
CPU Load: 0%
Thanks,
Anuj
Edited by: ***Anuj*** on Jul 12, 2011 2:22 PM

***Anuj*** wrote:
Hi all,
Our 11g database running on windows 2003 was hung. We bounced the database and reduced SGA_MAX_SIZE/SGA_TARGET =900M from 1200M. Problem was resolve.
SGA_MAX_SIZE/SGA_TARGET =1200M
PGA_AGGREGATE_TARGET=540M
Can anyone explain meaning of below line in trace file..
Memory (Avail/Total): Ph:1659M/4095M, Ph+PgF:13745M/16166M, VA:43M/2047M
1. Was there only 1659M available on Server for Oracle.exe?
2. Or Oracle.exe was looking for 1659M and could not get that?
3. What is the possiblity adding a /3g switch would have helped (if there was just 1659M free on server for Oracle , how /3g will help)
Errors In Alert log
ORA-27300: OS system dependent operation:CreateThread failed with status: 8
ORA-27301: OS failure message: Not enough storage is available to process this command.
ORA-27302: failure occurred at: sssxcpttcs4
In Trace file
ORA-27300: OS system dependent operation:CreateThread failed with status: 8
ORA-27301: OS failure message: Not enough storage is available to process this command.
ORA-27302: failure occurred at: sssxcpttcs4
OS tid = 10208
Memory (Avail/Total): Ph:1659M/4095M, Ph+PgF:13745M/16166M, VA:43M/2047M
CPU Load: 0%
Thanks,
Anuj
Edited by: ***Anuj*** on Jul 12, 2011 2:22 PMin the past the default maximum SGA size for 32-bit Oracle was 1.7G

Oracle 11g on Windows XP

Hello All,
I recently downloaded a copy of Oracle 11g for windows and installed it on my windows xp laptop.
I was able to install it without issues but I am unable to create a new database!
A little digging around revealed that there are very less no. of configurable parameters in 11g.
And that we don't have sga_max_size/sga_target anymore! Instead we have memory_target.
But inspite of ensuring all these changes, I keep running to the "end of file on communication channel" error.
Am I missing something here? I am using more-or-less the same approach to creating a database manually, that I have used for 9iR2; 10gR2 .
Any advise will be appreciated.
-Anand

Hello All,
I tried BOTH dbca as well as Manual Create database statement.
I finally managed to locate the alert log file and found a bunch of ORA-7445 Core Dump errors.
Note: With oracle 11g the background_dump_dest parameter is ignored and the alert log location is defined by the DIAGNOSTIC_DEST parameter.
And it points to:
<ORACLE_BASE>\diag\rdbms\<SID>\<SID>\trace
Wed Jul 09 17:03:22 2008
Starting ORACLE instance (normal)
Exception [type: IN_PAGE_ERROR, ] [] [PC:0x1026F5C, _ktfanfy()+0]
Errors in file c:\oracle\product\11g_base\diag\rdbms\hsa11gdb\hsa11gdb\trace\hsa11gdb_ora_3836.trc (incident=2):
ORA-07445: exception encountered: core dump [ktfanfy()+0] [IN_PAGE_ERROR] [] [PC:0x1026F5C] [] []
Incident details in: c:\oracle\product\11g_base\diag\rdbms\hsa11gdb\hsa11gdb\incident\incdir_2\hsa11gdb_ora_3836_i2.trc
Sweep Incident[2]: completed
I am digging deeper in metalink and will keep all posted with findings.
-Anand

Memory issue, Oracle 10g in Solaris 10 zone

I know many memory questions have been asked, but I couldn't find any similar to the problem I'm seeing.
Starting from a fresh server boot, I have 12G of available memory, or nearly that anyway. Oracle 10g is installed with no databases created.
After creating a database and running a few sql scripts to create tablespaces and users, my available memory is down to 3.5G.
Rebooting the solaris zone containing Oracle does not restore any available memory. Shutting down the database does not restore any available memory.
Why does Oracle seem to absorb so much available memory and not release it? I created the database from scripts and restricted the overall sga by a good bit over the defaults and while this did reduce the memory the oracle processes use, I'm still seeing this continual absorption of memory to the point where running any imports takes forever because my memory seems to bottom out. I saw it go down (using top, and vmstat) to about 500M at one point.
Is there any utility that I can use, either solaris or sqlplus that will free up system memory?
Message was edited by:
tsmori

After creating a database and running a few sql scripts to create tablespaces and users, my available memory is down to 3.5G.
What are your settings fpr SGA_MAX_SIZE, SGA_TARGET and PGA_AGGREGATE_TARGET?
Shutting down the database does not restore any available memory.
Hmm that's really strange. We are running Oracle 9i on Solaris 10 Containers and didn't have any problems with memory leaks.
Dim

Mpv cache size issue.

I update any VCS packages I use about once a month. After my June update mpv (mpv-git 0.38211.af25e0a-1) stopped playing radio streams - or so I thought.
Probably because of https://github.com/mpv-player/mpv/commi … c11e258671 my radio-playing script broke. I finally figured out it was because of cache fill, when it started playing a minute after I launched it. I fixed it by disabling the cache - the file is not seekable anyway. Setting cache to e.g. 64 KB, instead of the now-default 25000 KiB works too.
If you're using a current build of mpv-git, can you please try
mpv --no-config --cache=no http://xstream1.somafm.com:8880
and
mpv --no-config http://xstream1.somafm.com:8880
and see (hear) if there's any difference? You can try some different radio streams too. SomaFM's Underground Eighties has also another url they advertise as firewall-friendly: http://ice.somafm.com/u80s (in case you have problems with http://voxsc1.somafm.com:8880 ). Both streams are 128k mp3.
mpv 0.3.10-1 from the repos sets eh cache to 320 KiB but it's from before the change, as the man page still mentions --audiofile-cache.
I've never bothered to read mpv (or mplayer for that matter) man page. I wasn't even reading the console output as it was passed through awk (my radio-playing script). Disabling cache seems like the right solution, but I'd like to hear some other opinions and ideas before I put this in the wiki.
This thread will also make the issue a bit move visible for anyone who was left scratching their head after mpv update, like I was.

I am not specified SGA_MAX_SIZE, SGA_TARGET in pfile.
But in show parameter given below value
SQL> sho parameter SGA_MAX_SIZE
NAME TYPE VALUE
sga_max_size big integer 10743694360
SQL> sho parameter SGA_TARGET
SQL>
Regards
Mayil

Oracle Parameter file

Hi,
my Oracle DB is 10.2.0.5 version
O.s. Linux Red Hat
I need to modify some parameter into parameter file:
Some parameters are below:
audit_sys_operations
audit_trail
compatible
db_cache_size
event
java_pool_size
job_queue_processes
large_pool_size
pga_aggregate_target
processes
session_cached_cursors
sessions
sga_max_size
sga_target
into path $ORACLE_HOME/dbs I've these files:
init.ora
initdw.ora
spfileorcl.ora
pfileORCL.ora
orapworcl
spfileORCL.ora
Which step I have to perform to change these parameters?
Thanks in advance!

first of all check whether you are using pfile or spfile.
SHOW PARAMETER SPFILE;
If you get the output in the VALUE column then you can directly issue the below command to change the parameters:
ALTER SYSTEM SET <PARAMETER_NAME>=<VALUE>;
You need to use the SCOPE clause depending on the nature of the parameters.
If you dont get the output in the VALUE column, then its better to create the spfile by using the command:
CREATE SPFILE FROM PFILE;
Then you can use the above method.
And if you want to use the pfile only, then you have to change the parameters manually in that file.
Some parameter changes need the bouncing of the database, while some dont need.

SGA_MAX_SIZE & SGA_TARGET

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