Resizing SGA in 9i
Hi,
How to resize the SGA memory size in 9i. What are all the parameter needs to be change for this?
Right now, DB is running in pfile. Having sga_max_size = 6G.
Thanks in advance!!
There is plenty of info in the fine manuals
http://download.oracle.com/docs/cd/B10501_01/server.920/a96521/create.htm#998095
http://download.oracle.com/docs/cd/B10501_01/server.920/a96524/c08memor.htm#19799
http://download.oracle.com/docs/cd/B10501_01/server.920/a96533/memory.htm#38371
and more !
HTH
Srini
Similar Messages
-
Hi,
I am wokring on 10.2.0.4 and Hp-UX
right now i am using SGA_MAX_SIZE= XX MB and SGA_TARGET=XX MB and using kks_use_mutex_pin=False parameter .
now i want to set following values
SGA_MAX_SIZE= Not set
SGA_TARGET = Not set
Remove kks_use_mutex_pin paraneter ..
I m using spfile ...
how can i do this ...
alter system set SGA_MAX_SIZE= NULL/ ...? scope=both
or how ...oradba11 wrote:
Ok..
but in pfile what value i need to set for disable/No value SGA_MAX_SIZE parameter ...
i want to remove kks_use_mutex_pin parameter alos ...First why you want disable shared memory management?,oracle recommend that use ASMM.In additionally if you want using manual shared memory management then you have set sga_max_size and sga_target=0,and you have to set db_buffer_cahche/shared_pool/log_buffer initialization parameter ,you need manually manage these.If you use pfile then edit it then change these else you use spfile then change alter system set ... scope=spfile and restart database -
Can we resize SGA after setting SGA_MAX_SIZE to some number.
what parameters will be considered whule allocating this size.I hope you are talking about dynamic SGA feature of 9i. Following link would help you in this regards.
http://www.dbazine.com/burleson1.html -
Hi All,
what is the standard method to resize sga, and what are all the things to be considered. Is there any formulat to do that.
Regards
VenuThere are couple of good notes in metalink. However, there is no any thumb rule for siging SGA. I would recommend you to start with a reasonable value and increase accordingly, if required. It alos depends on whether your db is OLTP or DSS.
Jaffar
null -
Performance on Solaris 10 - Operating system paging
Has anyone experience performance issues after an upgrade from Solaris 9 to Solaris 10 on SAP systems with limited memory?
We have many systems that are on servers with 4 Gig of memory and ran well on Solaris 9. After an upgrade to Solaris 10 we are experiencing very high OS system paging rates. The response times of the SAP systems are very poor when this occurs. It seems to take very little load to cause this.
I realize more memory or decreases in Oracle or SAP memory parms will solve this but am wondering if there is anything on the Solaris OS that could resolve this?
Thanks,
DanDISM can be used but in global zone only (according to Sun document "Best Practive for Running Database in Solaris Containers" , the proc_lock_memory privilege which is required to run the ora_dism_ process is not available in non globale zone)
The doc i got is from 2005, so don't know if the Sun recommendations has been updated since then.
In order to activate DISM (if you are in a global zone), sga_max_size should be set up larger than the sum of sga components: db_cache_size, shared_pool_size ...)
Also look for the Sun Blueprint "Dynamic Reconfiguration and Oracle 9i Dynamic Resizable SGA" on http://www.sun.com/blueprints
If you use ISM because in a non-global zone, you can use oracle parameter lock_sga to ensure the SGA is loaded into the RAM and useism_for_pga = true to ensure PGA is loaded into the RAM.
Make sure you have enough RAM to hold filesystem cache (OS memory) , oracle memory, and applications memory
Make sur your PGA and SGA are correctly sized size, since you won't be able to dynamically change the ISM allocation. (see v$shared_pool_advice, v$db_cache_advice, v$pga_target_advice ...)
Take the usual precautions:
- have a successfull backup first
- do the change on a test machine
- and/or ask your vendor before proceeding
Other Doc to read ...
Note 697483 - "Oracle Dynamic SGA on Solaris" (recommends to read Sun doc n°230653)
Note 724713 - parameter settings for Solaris 10, here is an extract :
Only one parameter from SAP note 395438 should remain in file
etc/system
set rlim_fd_cur=8192
As described in SunSolve document 215536, the "Large Page Out Of the Box" (LPOOB) feature of the Solaris 10 memory management, first implemented in Solaris 10 1/06 (Update 1), can lead to performance problems when the system runs out of large chunks of free contiguous memory. This is because the Solaris 10 kernel by default will attempt to relocate memory pages to free up space for creating larger blocks of contiguous memory. Known symptoms are high %system CPU time in vmstat, high number of cross calls in mpstat, and Oracle calling mmap(2) to /dev/zero for getting more memory.
Memory page relocation for satisfying large page allocation requests can be disabled by setting the following Solaris kernel parameter in /etc/system
set pg_contig_disable=1
This will not switch off the LPOOB feature. Large memory pages will still be used when enough free space of contiguous memory is available, so the benefits of this feature will remain
Note 870652 - Installation of SAP in a Solaris Zone
Note 1246022 - Support for SAP applications in Solaris Zones
Edited by: Emmanuel TCHENG on Oct 13, 2009 12:02 PM -
Hello,
we have installed two zones with one oracle instance in each zone. It worked ok but our dba admins wants now to resize SGA in one zone to much bigger size (over half of the memory). But the problem is that Oracle says:
SQL> startup
ORA-27102: out of memory
SVR4 Error: 22: Invalid argument
in alert.log file:
Starting ORACLE instance (normal)
Mon Oct 17 13:19:56 2005
WARNING: EINVAL creating segment of size 0x0000000131c00000
fix shm parameters in /etc/system or equivalent
According to Solaris 10 documentation shmmax is obsolete now. After reading some docs I found out that shmmax is now defined as project.max-shm-memory. I want to increase the project.max-shm-memory to over half of the memory (the default size is 1/4 of memory). What is the best way to do that ? I found two ways of doing it (am I right ?!?!):
1) create pool, project (with definition of project.max-shm-memory), zone and associate the project with pool and pool with zone
2) create zone and inside the zone create project (and pool ?) and then run oracle under the project
Am I right that these are the two ways of increasing project.max-shm-memory ? Which is better ?
przemolEven though SUN says many of the kernel tunables are now obsolete in /etc/sytem, some like shmmax actually will still work if reset with the global zone. The default is 1/4 system memory.
-
Resizing Shared Pool or SGA Target??
I need to resize my shared pool to 512M
I am using 10g Enterprise Edition. 10.1.0.4 on windows 2003
Do i need to bounce the db or i can do this task using alter system command w/o shutting down the db??
I believe i will hv to resize the sga_maz_size aswell...
However is it true that if i set the sga_target.. everything will be taken care of.
I am trying to upgrade Oracle EM Grid Control from the basic 10.2.0.2 to 10.2.0.5
According to the read me file, the upgrade patch requires shared pool to be a minimum of 512M.
Note : this is a development server.. hence no applications, no testing is done on it now.. as of now for the smooth install and upgrade.. please help me with correct parameter and values to do this task.
Kind regardsPlease delete one of the posts.. double posting.
-
Tuning of SGA on Oracle 8.0.5 and AIX 4.3.3
Hi folks,
I have an AIX box running AIX 4.3.3 and Oracle 8.0.5.2.0. The original SGA settings are as follows:
shared_pool_size = 150000000
sort_area_size = 1024876
db_block_buffer = 126102
The SGA size then is:
Total System Global Area 1838467232 bytes
Fixed Size 47264 bytes
Variable Size 803287040 bytes
Database Buffers 1033027584 bytes
Redo Buffers 2105344 bytes
I changed the SGA settings to the following:
shared_pool_size = 768000000
sort_area_size = 512000000
The SGA size is now:
Total System Global Area 2227943584 bytes
Fixed Size 47264 bytes
Variable Size 214097920 bytes
Database Buffers 2013265920 bytes
Redo Buffers 532480 bytes
After this change was done, the system ran but the users had some problems running reports in JDEOneWorld.
I then downsize the SGA settings and altered the db_block_buffer to improve buffer cache hits with these settings:
db_block_buffers = 245760
shared_pool_size = 200000000
sort_area_size = 1048576
On restarting the database with the new values, I noted that the SGA size remained unchanged as below:
Total System Global Area 2278475936 bytes
Fixed Size 47264 bytes
Variable Size 264105984 bytes
Database Buffers 2013265920 bytes
Redo Buffers 1056768 bytes
I tried to increase the size of db_block_buffers to 327680 but encountered ORA-27123 when trying to startup the database. I did some searches in metalink and found an article saying that the SGA size cannot exceed 2GB on AIX platforms. (Doc ID: 114934.1). Therefore I resize the db_block_buffers back to 245760.
What puzzles me is why the SGA size does not reflect my latest init.ora settings? Does anyone have any idea on how I can get the SGA to reflect the updated values in the init.ora file?I did a find and here are the files I got:
278529 12 -rw-r--r-- 1 oracle dba 8332 May 12 1998 /u01/app/oracle/product/805/dbs/init.ora
278531 0 lrwxrwxrwx 1 oracle dba 43 Apr 14 2001 /u01/app/oracle/product/805/dbs/initklb.ora -> /u01/app/oracle/admin/klb/pfile/initklb.ora
278532 0 lrwxrwxrwx 1 oracle dba 45 Apr 14 2001 /u01/app/oracle/product/805/dbs/initklb_0.ora -> /u01/app/oracle/admin/klb/pfile/initklb_0.ora
49154 8 -rw-r--r-- 1 oracle dba 4657 Sep 7 2000 /u01/app/oracle/product/orig_db/initklb.ora
49155 8 -rw-r--r-- 1 oracle dba 4657 Jul 27 2000 /u01/app/oracle/product/orig_db/initklb_0.ora
151553 4 -rw-r--r-- 1 oracle dba 2985 Aug 4 2006 /u01/app/oracle/product/luz/pfile/initklb.ora
49161 8 -rw-r--r-- 1 oracle dba 4118 Oct 11 11:22 /u01/app/oracle/admin/klb/pfile/initklb.ora
135169 4 -rw-r--r-- 1 oracle dba 2896 Aug 4 2006 /u01/app/oracle/admin/klb/pfile/backup/initklb.ora
49168 8 -rw-r--r-- 1 root dba 4687 Jul 21 2001 /u01/app/oracle/admin/klb/pfile/archive/initklb1.ora
49162 8 -rw-r--r-- 1 oracle dba 4657 Dec 23 1999 /u01/app/oracle/admin/klb/pfile/archive/initklb_0.ora
The instance name is KLB so the applicable files are:
278531 0 lrwxrwxrwx 1 oracle dba 43 Apr 14 2001 /u01/app/oracle/product/805/dbs/initklb.ora -> /u01/app/oracle/admin/klb/pfile/initklb.ora
278532 0 lrwxrwxrwx 1 oracle dba 45 Apr 14 2001 /u01/app/oracle/product/805/dbs/initklb_0.ora -> /u01/app/oracle/admin/klb/pfile/initklb_0.ora
49154 8 -rw-r--r-- 1 oracle dba 4657 Sep 7 2000 /u01/app/oracle/product/orig_db/initklb.ora
49155 8 -rw-r--r-- 1 oracle dba 4657 Jul 27 2000 /u01/app/oracle/product/orig_db/initklb_0.ora
151553 4 -rw-r--r-- 1 oracle dba 2985 Aug 4 2006 /u01/app/oracle/product/luz/pfile/initklb.ora
49161 8 -rw-r--r-- 1 oracle dba 4118 Oct 11 11:22 /u01/app/oracle/admin/klb/pfile/initklb.ora
135169 4 -rw-r--r-- 1 oracle dba 2896 Aug 4 2006 /u01/app/oracle/admin/klb/pfile/backup/initklb.ora
49168 8 -rw-r--r-- 1 root dba 4687 Jul 21 2001 /u01/app/oracle/admin/klb/pfile/archive/initklb1.ora
49162 8 -rw-r--r-- 1 oracle dba 4657 Dec 23 1999 /u01/app/oracle/admin/klb/pfile/archive/initklb_0.ora
Now, exclude the files in the product, backup and archive directories (the pfile should be in the pfile directory), and that leaves us with:
49161 8 -rw-r--r-- 1 oracle dba 4118 Oct 11 11:22 /u01/app/oracle/admin/klb/pfile/initklb.ora
(Which is the file that I edited)
As I mentioned previously, my client is not prepared to perform an upgrade on both Oracle and AIX. As much as I would like to have them upgrade to the latest versions, it is just not possible.
Oracle 8.0.5 does not have spfiles, so there is no way for me to edit a spfile unless this is one of those undocumented tricks floating around. -
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 AMI 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 -
Dear All,
We are using Oracle 10g R2 on windows 2003.Our sga_max_size=2000m and sga_target=800m.We have enabled ASM.
I got an alert message in enterprize manger which says virtual memory paging is happening and its impact is 100%.
Now,Is this problem related to SGA?Do i have to resize my sga_max_size ?
We have 4gb RAM 460 gb hard disk what would be the ideal size for sga?
Regards,
KrisFor guidelines over SGA & memory, refer discussion here...
Re: windows 32bit sga and pga limits
But actual sizing of SGA depends on your application needs. If it needs more SGA, it does. You might need to add more RAM to your server to cope up with existing workload for a given number of users. -
We bought a server for oracle data warehousing which has got 200GB RAM. Can I set set my SGA_TARGET to 100GB. Is it true the more SGA size result in better performance.
Thaks
jeevanHi Jeevan,
I would not set sga_target, it can cause RAM thrashing . . .
In an article titled Automatic Shared Memory Management we see:
http://www.oracle.com/technology/pub/articles/10gdba/week17_10gdba.html
Some pools in SGA are not subject to dynamic resizing, and must be specified explicitly. Notable among them are the buffer pools for nonstandard block sizes and the non-default ones for KEEP or RECYCLE. If your database has a block size of 8K, and you want to configure 2K, 4K, 16K, and 32K block-size pools, you must set them manually.
Their sizes will remain constant; they will not shrink or expand based on load. You should consider this factor when using multiple-size buffer, KEEP, and RECYCLE pools.
In addition, log buffer is not subject to the memory adjustment—the value set in the parameter log_buffer is constant, regardless of the workload. ( In 10g, a new type of pool can also be defined in the SGA: Streams pool, set with parameter streams_pool_size. This pool is also not subject to automatic memory tuning.)
Is it true the more SGA size result in better performance. Yes, but it may not be much, or it could be alot! It depends.
On a dedicated server, your goal is to allocate all the RAM, without causing swapping. I have my notes here:
http://www.dba-oracle.com/art_dbazine_ram.htm
Hope this helps . . .
Donald K. Burleson
Oracle Press author
Author of "Oracle Tuning: The Definitive Reference"
http://www.rampant-books.com/book_2005_1_awr_proactive_tuning.htm -
(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 Architecture842638 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.... -
ASMM - sga dynamic components and standby
Are SGA dynamic modifications "transferred" from the primary to the standby?
i.e: if __shared_pool is resized in primary will this also trigger standby?
Trying to determine if dynamic pools may somehow end up being different upon switchover/failover or if it's possible that upon switchover standby's dynamic shared_pool size results smaller than that of former primaryAbsolutely, yet there are some things DG broker does upon switch over. Was wondering if somehow standby would be "updated" upon switcher...
But then again, it's SGA as a hole may be smaller to begin with...
Were you to tell if the following is true or false:
"After activation standby database may have a SGA configuration different than that of primary"
what would you say?
Hole intention here is to determine whether after a switch over it's possible to start getting ORA-04031 on account of dynamic pools being different
and oracle struggling to re-size them...
Suppose we have a 6Gb SGA... primary has been working full steam for say 2 months and dynamic pools are set by oracle in the following way:
shared_pool...3Gb
cache...3Gb
Now if standby has not acknowledged those dynamic changes, it may be using values of it's own... maybe a larger cache... say
shared_pool...1Gb
cache...5Gb
Now we switch-over and if sga settings are not "synced", then new primary will have 2Gb less of shared pool...
Application kicks in, shared pool runs low... Oracle will have to move 1 or 2Gbs from cache to shared pool, this will cause serious latching and most likely ORA-04031
so is that likely to happen? -
Constant change in SGA components up-down
hello,
we are developement database oracle 10gR2 on windows plateform
ASMM is on.
i am surprised to know that our smart oracle is doing a lot of shrink and grow on SGA components specially shared pool and db buffer cache
is it ok or some thing wrong?
i checked another development DB and found that it should be infrequent..
do i need to turn of the ASMM?
the out put from a query shown this
WHEN COMPONENT OPER_TYPE INITIAL_SIZE/1024 FINAL_SIZE/1024
May-16:19:53:17 DEFAULT buffer cache STATIC 3031040 3014656
May-16:19:53:17 large pool GROW 0 16384
May-16:19:53:17 DEFAULT buffer cache INITIALIZING 3031040 3014656
May-16:19:53:17 ASM Buffer Cache STATIC 0 0
May-16:19:53:17 DEFAULT 32K buffer cache STATIC 0 0
May-16:19:53:17 DEFAULT 16K buffer cache STATIC 0 0
May-16:19:53:17 DEFAULT 8K buffer cache STATIC 0 0
May-16:19:53:17 DEFAULT 4K buffer cache STATIC 0 0
May-16:19:53:17 DEFAULT 2K buffer cache STATIC 0 0
May-16:19:53:17 RECYCLE buffer cache STATIC 0 0
May-16:19:53:17 KEEP buffer cache STATIC 0 0
May-16:19:53:17 DEFAULT buffer cache STATIC 0 3014656
May-16:19:53:17 streams pool STATIC 0 0
May-16:19:53:17 java pool STATIC 0 16384
May-16:19:53:17 large pool STATIC 0 16384
May-16:19:53:17 shared pool STATIC 0 688128
May-16:20:30:59 shared pool GROW 688128 704512
May-16:20:30:59 DEFAULT buffer cache SHRINK 3014656 2998272
May-17:10:50:40 DEFAULT buffer cache SHRINK 2998272 2981888
May-17:10:50:40 streams pool GROW 0 16384
May-17:10:50:42 DEFAULT buffer cache SHRINK 2981888 2965504
May-17:10:50:42 streams pool GROW 16384 32768
May-17:11:04:38 shared pool GROW 704512 737280
May-17:11:04:38 DEFAULT buffer cache SHRINK 2965504 2932736
May-17:11:05:08 shared pool GROW 737280 770048
May-17:11:05:08 DEFAULT buffer cache SHRINK 2932736 2899968
May-17:11:06:01 DEFAULT buffer cache SHRINK 2899968 2883584
May-17:11:06:01 shared pool GROW 770048 786432
May-17:11:20:38 DEFAULT buffer cache SHRINK 2883584 2850816
May-17:11:20:38 shared pool GROW 786432 819200
May-28:15:24:06 DEFAULT buffer cache SHRINK 2850816 2818048
May-28:15:24:06 shared pool any suggations/advice/help??
thank youI saw this a lot on an highly OLTP system once at 10gR2. My SGA was thrashing wildly between buffer cache and shared pool due to a bug in AMM and it was causing performance impact (cursor S pin on X) for no apparent reason. This was particularly prevalent when I moved from a two to a three node cluster.
If you check out v$sga_resize_ops and see if you see a lot of thrashing (sometimes once every three seconds on one instance for 3 hours, then it'd switch to another instance), then my solution was to hardcode the various settings and disable AMM. However, in your case, you're resizing fairly irregularly - probably due to either an undersized component or workload changes. AMM is meant to do what you're describing - is it causing you any issue or is it something that you've noticed and are curious about? -
DB : 10.2.0.4.
Solaris 10
V$SGA_TARGET_ADVICE
SGA_SIZE SGA_SIZE_FACTOR ESTD_DB_TIME ESTD_DB_TIME_FACTOR Estd Phys Reads
3840 .25 3232050 1.7373 899,492,073
7680 .5 1989312 1.0693 491,807,585
11520 .75 1887363 1.0145 483,839,033
15360 1 1860387 1 477,158,810
19200 1.25 1828574 .9829 477,158,810
23040 1.5 1811831 .9739 452,537,415
26880 1.75 1784855 .9594 452,537,415
30720 2 1784855 .9594 452,537,415
select * from V$SHARED_POOL_ADVICE;
SHARED_POOL_SIZE_FOR_ESTIMATE SHARED_POOL_SIZE_FACTOR ESTD_LC_SIZE ESTD_LC_MEMORY_OBJECTS ESTD_LC_TIME_SAVED ESTD_LC_TIME_SAVED_FACTOR ESTD_LC_LOAD_TIME ESTD_LC_LOAD_TIME_FACTOR ESTD_LC_MEMORY_OBJECT_HITS
4448 0.4938 1003 60183 292126109 0.976 9889315 3.6641 471339446
5360 0.595 1906 92900 295279970 0.9865 6735454 2.4955 478822120
6272 0.6963 2817 135896 296561700 0.9908 5453724 2.0206 482918542
7184 0.7975 3727 181357 297393539 0.9936 4621885 1.7124 493254538
8096 0.8988 4635 220801 298361940 0.9968 3653484 1.3536 505060512
9008 1 5545 261361 299316429 1 2698995 1 513945687
9920 1.1012 6454 302969 299825751 1.0017 2189673 0.8113 519805862
10832 1.2025 7364 339053 300255540 1.0031 1759884 0.6521 523957488
11744 1.3037 8275 378601 300634363 1.0044 1381061 0.5117 526926143
12656 1.405 9185 417826 300896107 1.0053 1119317 0.4147 529096861
13568 1.5062 10095 459922 301113075 1.006 902349 0.3343 530783472
14480 1.6075 11005 498736 301345932 1.0068 669492 0.2481 532135345
15392 1.7087 11916 537009 301509644 1.0073 505780 0.1874 533262509
16304 1.8099 12827 578447 301627190 1.0077 388234 0.1438 534189757
17216 1.9112 13738 619789 301731503 1.0081 283921 0.1052 534989978
18128 2.0124 14649 657592 301824963 1.0084 190461 0.0706 535717904
SIZE_FOR_ESTIMATE SIZE_FACTOR BUFFERS_FOR_ESTIMATE ESTD_PHYSICAL_READ_FACTOR ESTD_PHYSICAL_READS ESTD_PHYSICAL_READ_TIME ESTD_PCT_OF_DB_TIME_FOR_READS ESTD_CLUSTER_READS ESTD_CLUSTER_READ_TIME
624 0.1 74841 2.6614 47516415301 94395449 191.3 3647787264 4146408
1248 0.2 149682 1.6766 29934104258 43087455 87.3 2298011136 2612129
1872 0.3 224523 1.371 24476781857 27162117 55 1879057920 2135908
2496 0.4 299364 1.2222 21820896898 19411827 39.3 1675168384 1904149
3120 0.5 374205 1.1306 20185187699 14638567 29.7 1549596672 1761413
3744 0.6 449046 1.0703 19109692149 11500095 23.3 1467031808 1667562
4368 0.7 523887 1.0325 18434906180 9530958 19.3 1415229184 1608678
4992 0.8 598728 1.0144 18111181243 8586282 17.4 1390377088 1580429
5616 0.9 673569 1.0052 17947537521 8108739 16.4 1377814400 1566149
6240 1 748410 1 17853869396 7835403 15.9 1370623616 1557976
6864 1.1 823251 0.9971 17802737449 7686190 15.6 1366698240 1553514
7488 1.2 898092 0.9957 17777323790 7612035 15.4 1364747264 1551296
8112 1.3 972933 0.9949 17762716920 7569405 15.3 1363625856 1550021
8736 1.4 1047774 0.9943 17752761824 7540354 15.3 1362861696 1549153
9360 1.5 1122615 0.9939 17745136756 7518104 15.2 1362276352 1548487
9984 1.6 1197456 0.9936 17739260102 7500951 15.2 1361825152 1547975
10608 1.7 1272297 0.9933 17734415936 7486817 15.2 1361453312 1547552
11232 1.8 1347138 0.993 17729261699 7471781 15.1 1361057664 1547102
11856 1.9 1421979 0.9925 17719763099 7444057 15.1 1360328320 1546273
12480 2 1496820 0.9603 17144546936 5765489 11.7 1316169600 1496078ON EM,
Finding The SGA was inadequately sized, causing additional I/O or hard parses.
Impact (minutes) 129.7
Impact (%) 20.2
Increase the size of the SGA by setting the parameter "sga_target" to 26880 M
Currently , SGA is sized 16G and we have 32GB RAM On the machine and we are planning to increase the RAM t 128G.. ADDM and AWR reports confirms the same.
Upon the above considerations, can I increase the SGA to atleast 26880M.
Plese guide?
KaiHi Kai,
Upon the above considerations, can I increase the SGA to atleast 26880M. Just beware, in 10.2 some databases have performance issues that are caused by resizing operations:
http://www.dba-oracle.com/t_amm_automatic_memory_resize.htm
BTW, there is also weirdness in 11g AMM:
http://www.oraclealchemist.com/oracle/strange-behavior-with-memory_target/
You might consider doing manual pool sizing, if this applies to you . . .
ADDM and AWR reports confirms the same. ADDM has been known to make naive and reckless recommendations . . .
This increase seems fishy to me, I would run the buffer pool advisory independently . . .
Hope this helps . . .
Donald K. Burleson
Oracle Press author
Author of "Oracle Tuning: The Definitive Reference"
http://www.rampant-books.com/book_2005_1_awr_proactive_tuning.htm
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