SGA+PGA Size allocation

Hi all
I Have a server System Configuration with
RAM size: 16GB Ram & Hard disk Size of 1TB.
I Installed Oracle 11g R2 in the server System
I want to Allocate Dedicated Memory for oracle..
How Should i calculate the Memory size of SGA+PGA for good Performance..

Pl do not post duplicates - Reg:-SGA & PGA Memory Allocation Size

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Reg:-SGA & PGA Memory Allocation Size

Hi all
I Have a server System Configuration with
RAM size: 16GB Ram & Hard disk Size of 1TB.
I Installed Oracle 11g R2 in the server System
I want to Allocate Dedicated Memory for oracle..
How Should i calculate the Memory size of SGA+PGA for good Performance..

Check MOS
*How to calculate the memory used by dedicated and shared servers? [ID 551415.1]*

SGA/PGA Sizes ???

I need help!
I have a Windows 2003 Server (w/sp2) with 4GB of RAM & 2 CPUs. Oracle 10.2.0.2 is installed.
ASMM is ENABLED by default (and it still is)
These are my sga/pga settings:
pga_aggregate_target = 1G
sga_max_size = 1504M
sga_target = 1000M
shared_pool_size = 504M
sort_area_size = 262144000 (250M)
large_pool_size = 104M
db_cache_size = 104M
I believe I should DISABLED ASMM, correct? Otherwise, my settings aren't used.
Based on my 4GB, I think Oracle can use 2GB of that.
What should I set the settings above too?
...thanks

First if you use Oracle's automatic memory management feature and provide spfile parameter values for parameters that are automatically managed by Oracle then the provided values are taken as minimum values for these areas. There are other situations where values for parameters like sort_area_size which is limited to 5% of pga_aggregate_target are in fact still referenced.
With a pga_aggregate_target of 1G I do not see any valid reason why you would have a sort_area_size set to 250M. What is the reason for this?
What kind of environment is this: OLTP, DSS, OLAP?
How many concurrent sessions?
Dedicated vs shared server?
Why do you not want to use automatic memory management? What problem have you encountered?
HTH -- Mark D Powell --

How to recommand sga & pga size for existing database?

Hi All,
In my environment there are 100s of databases running , in few servers we frequently getting the "Unable to allocate the shared memory" during job process. But the server have enough memory to allocate to the databases where ever the memory required.
Now the quesition is how to predict or estimate the required memory of that database?
Thanks

903787 wrote:
Hi All,
In my environment there are 100s of databases running , in few servers we frequently getting the "Unable to allocate the shared memory" during job process. But the server have enough memory to allocate to the databases where ever the memory required.
Now the quesition is how to predict or estimate the required memory of that database?
Thanksquery V_$SGA_TARGET_ADVICE

Oracle 11g SGA & PGA setup

Hi I installed oracle 11g & create database , now i want to use fully optimize database.
Currently my DB server RAM is 16GB, how should i allocate SGA for this.If i used oracle 11g automatic memeory management feature to allocate SGA+PGA, how should i use them.Currentlymy SGA is set to 4GB, Please advise

Hi,
It is depends upon the workload which you have in your organization(future and present situation)
SGA+PGA size will be automatically managed by Oracle. No need to worry about this.
If you need to increase Memory_Max_Size, you can also increase the Memory size in the future.
Thanks

SGA, PGA & RAM Size?

our DB running in dedicated server mode(FYI).
am defining my SGA size 500MB, which is half the size of DB server 1gb RAM, it does not mean that my instance will not go beyond 500mb, if multiple users are connected & start using Sorts,(SORT_AREA_SIZE =1mb), apart from 500mb, each user whoever using sort area space will be allocated 1mb space in 1gB RAM, is it correct?
since SORT_AREA_SIZE can be modified at session level,each user can set their own sort area size, which may lead to paging, is it correct?
Sorts uses memory from PGA,PGA is not part of SGA,hence how to determine the PGA size?, is there any init.ora parameter for sizing PGA in ORACLE 8.1.7?

The size of PGA will depends upon the containts of PGA which are Sort Area, Session Statistics Information, Stack Space, Cursor Information
I am not aware of any parameter to size the PGA.
I will check the documentation and will let you know.
Manu

Increase the SGA and PGA size

Hello Guru,
How do i check what is my SGA and PGA..I am using TOAD..
I need to increase the SGA and PGA size...Please help..
I have a table having 200 million records, all indexes are there for the column..But it hang on in the debugging mode and also compile mode..
So i believe, I need to increase the SGA and PGA size...
Thanks,
Haraprasad...

805936 wrote:
Hello Guru,
How do i check what is my SGA and PGA..I am using TOAD..
I need to increase the SGA and PGA size...Please help..
The current size for both SGA and PGA can be shown depending on the version of the db. For 10g, the SGA size is shown by sga_target parameter and PGA size is shown by pga_aggregate_target parameter. For 11g, the parameter memory_target sets them both.
I have a table having 200 million records, all indexes are there for the column..But it hang on in the debugging mode and also compile mode..
So i believe, I need to increase the SGA and PGA size...No, IMO, your believe doesn't hold much base as the evidence that you have used is insufficient. What is the debugging mode or compile mode ? For what purpose you are using these modes? 200 million is not a very large number if you ask me. Tell us your db version and based on it, generate a Statspack or AWR report and post here.
HTH
Aman....

PGA Size

Hi All,
I have a little question, in our database configuration we have set the PGA size to 720 MB. I'm wondering do we need all this memory size?!!
All our applications that connect to the database are using normal select and dml statements no use of varray of bulk collect. So my questions are:
1. When a new session is established, an allocation of 720 MB is done for that session?
2. the swap file usage is around 33% of 33 GB size, If i reduce PGA size to 100MB for example, it will reduce my swap file usage?
Thankx in advance.

Hi,
My Operating system is HP-UX ita. B11.23
My database version is 9i RAC (9.2.0.6) 2 Instance
OS Ram Size on each instance 16 GB
My SGA Size is 4 GB
I have no accurate method to size my session, but all of the database objects (Function, packages, ..) is using normal PL/SQL and SQL no use of advanced varray, bulk collect, etc.
Here is the result of my select * from v$pgastat (Inst1)
aggregate PGA target parameter     754974720
aggregate PGA auto target     435566592
global memory bound     37748736
total PGA inuse     270964736
total PGA allocated     310807552
maximum PGA allocated     783979520
total freeable PGA memory     11403264
PGA memory freed back to OS     4.63335E+11
total PGA used for auto workareas     16384
maximum PGA used for auto workareas     83709952
total PGA used for manual workareas     0
maximum PGA used for manual workareas     0
over allocation count     0
bytes processed     4.61963E+12
extra bytes read/written     10748186624
cache hit percentage     99.76
For instance2
aggregate PGA target parameter     754974720
aggregate PGA auto target     435566592
global memory bound     37748736
total PGA inuse     270964736
total PGA allocated     310807552
maximum PGA allocated     783979520
total freeable PGA memory     11403264
PGA memory freed back to OS     4.63335E+11
total PGA used for auto workareas     16384
maximum PGA used for auto workareas     83709952
total PGA used for manual workareas     0
maximum PGA used for manual workareas     0
over allocation count     0
bytes processed     4.61963E+12
extra bytes read/written     10748186624
cache hit percentage     99.76
My main concern is is that i want to eleminate Oracle usage of swap file, What should i do ?
I tried to minimize the use of FULL table scans, physical (Disk) reads and also minimize the number of logical (Buffer) reads by checking the values from select * from v$sql on both instances.
can you help me with more ideas to do?
Thanks in advance.

SGA/PGA (Memory) in RAC environment.

Guys,
I would like to get your inputs on SGA / PGA settings on a RAC database.. Does LMS/LMON/LMD process use memory which is part of PGA or these process allocate memory at OS level ?
I would like to see the usage of Memory used by a database.
below sql from Mr. Kyte's website i have used. Somehow i am not getting real usage of the system. Any help would be appreciated.
Thanks
select
ssst.sid,
stn.name ,
round(ssst.value/1024/1024,2) memory ,
USERNAME,
COMMAND,
OSUSER,
MACHINE,
TERMINAL,
PROGRAM ,
ssst.STATISTIC#
from v$statname stn,v$sesstat ssst , v$session ses
where stn.STATISTIC# = ssst.STATISTIC# and
ssst.sid = ses.sid and
name like 'session%pga%memory%'
order by 3 asc ;
Edited by: P explorer on Aug 28, 2009 9:56 PM

From sql script, that get "session pga memory","session pga memory max" each of session in oracle database(on that node)
You'll see
sid: session id
memory:
if "session pga memory" = pga memory in this session now
if "session pga memory max"= maximum pga memory in this session.
program: os program name
More deatails abour v$session http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/dynviews_2088.htm#REFRN30223
If need to know all PGA size in that node
"session pga memory":
select
round(sum(ssst.value)/1024/1024,2) memory
from v$statname stn,v$sesstat ssst , v$session ses
where stn.STATISTIC# = ssst.STATISTIC# and
ssst.sid = ses.sid and
name ='session pga memory';
"session pga memory max":
select
round(sum(ssst.value)/1024/1024,2) memory
from v$statname stn,v$sesstat ssst , v$session ses
where stn.STATISTIC# = ssst.STATISTIC# and
ssst.sid = ses.sid and
name ='session pga memory max';
Or if you need to check PGA memory all nodes (RAC)
COLUMN username FORMAT A20
COLUMN module FORMAT A20
SELECT a.inst_id,
NVL(a.username,'(oracle)') AS username,
a.module,
a.program,
Trunc(b.value/1024) AS memory_kb
FROM gv$session a,
gv$sesstat b,
gv$statname c
WHERE a.sid = b.sid
AND a.inst_id = b.inst_id
AND b.statistic# = c.statistic#
AND b.inst_id = c.inst_id
AND c.name = 'session pga memory'
AND a.program IS NOT NULL
ORDER BY b.value DESC;

Huge long time direct path read temp, but pga size is enough, one block p3

Hi Gurus,
Can you please kindly provide some points on my below questions. thanks
my env
select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
OS: Linux 4 2.6.39-100.5.1.el5uek
session operation: update a partition which have 4 partitions and total 16G
session trace info:
the session keep at active status and waiting for below wait event for more than 70 hours, and os iostats and cpu are almost idle on most time.
WAIT #8: nam='direct path read temp' ela= 7615 file number=202 first dba=105072 block cnt=1 obj#=104719 tim=1344850223569499
WAIT #8: nam='direct path read temp' ela= 5989 file number=202 first dba=85264 block cnt=1 obj#=104719 tim=1344850392833257
WAIT #8: nam='direct path read temp' ela= 319 file number=202 first dba=85248 block cnt=1 obj#=104719 tim=1344850399563184
WAIT #8: nam='direct path read temp' ela= 358 file number=202 first dba=85232 block cnt=1 obj#=104719 tim=1344850406016899
WAIT #8: nam='direct path read temp' ela= 349 file number=202 first dba=85216 block cnt=1 obj#=104719 tim=1344850413023792
WAIT #8: nam='direct path read temp' ela= 7975 file number=202 first dba=85200 block cnt=1 obj#=104719 tim=1344850419495645
WAIT #8: nam='direct path read temp' ela= 331 file number=202 first dba=85184 block cnt=1 obj#=104719 tim=1344850426233450
WAIT #8: nam='direct path read temp' ela= 2641 file number=202 first dba=82880 block cnt=1 obj#=104719 tim=1344850432699800
pgastat:
NAME VALUE/1024/1024 UNIT
aggregate PGA target parameter 18432 bytes
aggregate PGA auto target 16523.1475 bytes
global memory bound 1024 bytes
total PGA inuse 75.7246094 bytes
total PGA allocated 162.411133 bytes
maximum PGA allocated 514.130859 bytes
total freeable PGA memory 64.625 bytes
PGA memory freed back to OS 40425.1875 bytes
total PGA used for auto workareas 2.75195313 bytes
maximum PGA used for auto workareas 270.407227 bytes
total PGA used for manual workareas 0 bytes
NAME VALUE/1024/1024 UNIT
maximum PGA used for manual workareas 24.5429688 bytes
bytes processed 110558.951 bytes
extra bytes read/written 15021.2559 bytes
Most operation in PGA via query on V$SQL_WORKAREA_ACTIVE
IDX maintainenance (sort)
My questions:
1. why 'direct path read temp' just read one block every time, my understanding is this event can read one block and multiple blocks at one read call, why it keep read one block in my session?
2. my pga size is big enough, why this operation can not be treated with in PGA memory, instead of read block from disk into temp tablespace?
Thanks for you inputs.
Roy

951241 wrote:
since the session(which was from hard code application) is completed.First of all, you showed wait events from sql trace in the first post. Is the tracing was disabled in the latest execution?
>
I just generated the AWR for that period, as get long elapsed time SQL as following
Elapsed Time (s) Executions Elapsed Time per Exec (s) %Total %CPU %IO SQL Id
3,075.35 0 85.10 91.03 8.68 duhz2wtduz709
524.11 1 524.11 14.50 99.29 0.30 3cpa9fxny9j35
so I get execution plan as below for these two SQL,
select * from table(dbms_xplan.display_awr('&v_sql_id')); duhz2wtduz709
PLAN_TABLE_OUTPUT
| Id | Operation         | Name        | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | UPDATE STATEMENT |             |       |       |     4 (100)|          |
|   1 | UPDATE           | WORK_PAY_LINE |       |       |            |          |
|   2 |   INDEX RANGE SCAN| WORK_PAY_LINE |     1 |    37 |     3   (0)| 00:00:01 |
Note
- automatic DOP: Computed Degree of Parallelism is 1 because of parallel thresholdI am not sure the why elapsed time in AWR is different with time in execution plan. Column "Time" in an execution plan is estimated time. In this execution plan Oracle expects to get 1 row, estimated time is 1 sec.
So, you need to check why estimated cardinality is such low, check statistics on the table WORK_PAY_LINE.
You update 10Gb from 16Gb table via Index Range Scan, it looks inefficient here by two reasons:
1. when a table updated via Index Range Scan optimized index maintenance is used. As a result some amount (significant in your case) of workareas is required. Required size depends on size and number of updated indexes and "global memory bound", 1Gb in your case.
2. if required table buffers will not be found in the cache it will be read from disk by single block reads. If you would use Full Table Scan then buffers for update most likely will be found in the cache because before it read by multiblock reads during Full Table Scan.
Figures from your AWR indicate, that only ~ 9% the session waited for I/O and 91% it worked and used CPU
Elapsed Time (s) Executions Elapsed Time per Exec (s) %Total %CPU %IO SQL Id
3,075.35 0 85.10 91.03 8.68 duhz2wtduz709 This amount of CPU time partially required for UPDATE 10Gb of data, partially for sorting during optimized index maintenance.
I would propose to use Table Full Scan here.
Also you can play around and create fake trigger on update, it will make impossible to use optimized index maintenance, usual index maintenance will be used. As a result you can check the same update with the same execution plan (with Index Range Scan) but without optimized index maintenance and "direct path .. temp" wait events.
Alexander Anokhin
http://alexanderanokhin.wordpress.com/

SGA & PGA target

Hi all,
My questions is regarding how to set up SGA & PGA target values giving DB server is MS 2003 Enterprise 64 edition sever with 63 GB of RAM. Our DB’s version is 10.2.0.3 and RACed with 2 instances.
Currently our setting for SGA is 23 GB and PGA is 4 GB. I ran the memory advisor it display different optimal values for those two instances (35 GB and 23 GB for SGA, 5 GB and 4 GB for PGA). Guess our db is not well balance loaded.
I would like to know if there is any rule(s) that SGA can’t be more than certain percentage of total RAM for the server.
Thanks a lot in advance.
Have a great weekend!!
Shirley

Hi
Here is my approach:
1) consider free physical memory (meassure must be taken with Oracle down)
2) substract a 10% of that amount as a margin
3) if the box is exclusive for Oracle, the remaining amount may be your SGA+PGA limit
4) if not is exclusive, then substract memory required for other services, then you'll get the SGA+PGA limit.
5) Substract your PGA size, giving the SGA figure
For instance
59 Gb - 6 Gb = 53 Gb - 4 Gb = 49 Gb
(63 Gb -4 Gb [estimated OS footprint + IO cache]) = 59 Gb free physical memory
Setting PGA+SGA beyond the free physical memory figure, may lead to swaping and degraded system performance.
Regards
http://oracledisect.blogspot.com

SGA, PGA and... little extra?

Will oracle process use some extra "non oracle" memory for OS related stuff?
Mean, not considering SGA, I connect a database process and I see:
SQL> select p.program,
2 p.spid, pm.category, pm.allocated/1024 allocated, pm.used/1024 used, pm.max_allocated/1024 max_allocated
3 from V$PROCESS p, V$PROCESS_MEMORY pm
4 where p.pid = pm.pid
5 and p.spid =2650;
                                                                                                        Max
                                                                          Allocated       Usedd   allocated
PROGRAM                        SPID                     CATEGORY                 Kb          Kb          Kb
oracle@uxlabhost11             2650                     SQL                      14           9          42
oracle@uxlabhost11             2650                     PL/SQL                   56          34          57
oracle@uxlabhost11             2650                     Other                  1501                    1501That's allocated PGA after having connected and done nothing else
So it somehow allocated 1.4 Mb upon start-up...
Now question is. Do oracle processes use OS memory which cannot be considered as SGA or PGA?
Reason being my trying to estimate memory needs for a database server. Many I've read correct formula should be SGA + max allocated PGA + some_extra_just_in_case...
Is there an estimate on how much that "some_extra_just_in_case" would be per process?
If OS dependent, I'm implementing on RHEL 6...
thanks

So, I've used pmap...
Got 257 enties in the form "4096K rw-s- /dev/shm/"
since we are using AMM , that should do for PGA and SGA ... some 1052672 Kb, which process is attached to...
yet pmap then continues to display other entries....
0000002a95557000      4K r-x-- /opt/oracle/product/11g/lib/libodm11.so
0000002a95558000   1024K ----- /opt/oracle/product/11g/lib/libodm11.so
0000002a95658000      4K rw--- /opt/oracle/product/11g/lib/libodm11.so
0000002a95659000      4K rw---    [ anon ]
0000002a9565a000    392K r-x-- /opt/oracle/product/11g/lib/libcell11.so
0000002a956bc000   1024K ----- /opt/oracle/product/11g/lib/libcell11.so
0000002a957bc000     40K rw--- /opt/oracle/product/11g/lib/libcell11.so
0000002a957c6000      4K rw---    [ anon ]
0000002a957c7000    864K r-x-- /opt/oracle/product/11g/lib/libskgxp11.so
.. TRUNCATED...
0000003fb810a000     64K rw---    [ anon ]
0000003fbbd00000     84K r-x-- /lib64/libnsl-2.3.4.so
0000003fbbd15000   1020K ----- /lib64/libnsl-2.3.4.so
0000003fbbe14000      4K r---- /lib64/libnsl-2.3.4.so
0000003fbbe15000      4K rw--- /lib64/libnsl-2.3.4.so
0000003fbbe16000      8K rw---    [ anon ]
0000007fbffde000    136K rwx--    [ stack ]
ffffffffff600000      4K r-x--    [ anon ]
total          1276452KNotice "total 1276452K"
So you saying non SGA/PGA would be 1276452 - 1052672?
That would be too much... yet if pmap another process, almost all flags (hex column) but [ stack ] are the same....
So how to tell which of those are shared and which are "exclusive" to the process, i.e: The "some extra just in case" mem...
thanks

Sga max size is different

We use Oracle 11gr2 on win2008R2.
Our member set sga max size by
alter system set sga_max_size scope=spfile; max size to 6GB.
And we restared that OS and DB instance , then
show parameters sga_max_size was 7.6GB
Why is that ?

If MEMORY_TARGET is set to a non-zero value:
If SGA_TARGET and PGA_AGGREGATE_TARGET are set, they will be considered the minimum values for the sizes of SGA and the PGA respectively. MEMORY_TARGET values can range from SGA_TARGET + PGA_AGGREGATE_TARGET to MEMORY_MAX_TARGET.
Now check if your memory_target is set.
Read this metalink note as well:
Automatic Memory Management (AMM) on 11g (Doc ID 443746.1)

Sga&pga

Hi all;
i wanna learn something about sga and pga... I have r11 instance on linux and db version is 10.2.0.3...Let say my sga=5 Gb and pga is=3gb...my server has 20gb ram...when i look my usage by top command and i see that:
Mem: 20550320k total, 20491732k used why linux allocate all those area?
i have 20 Gb ram and sga+pga=8 soo which oracle process use 12 Gb?
and advicer gives me adivice about SGA... it offers 10 Gb SGA... if i rise my sga what is my benefit? what it would change?
thanks alot

Hi hussien;
Thanks for again answers and help
You need to identify what other processes are running on this node. For example, if you have CM running on the database tier node, then it is expected to find more memory allocated. You can simply stop all the services on the server and start it one by one, and each time and keep an eye on the allocated memory.Its my mistake, coz i talked wiht my client and they said me they are working on this machine and thatswhy i had this memory usage.. sory for this mistake again (but your post helped me alot,coz i asked them what they are doing for a now ,and they gave me that answer :),thanks for leading)
Since you are on 10g, I would suggest you also go through the following document.
Note: 295626.1 - How To Use Automatic Shared Memory Management (ASMM) In Oracle10g
https://metalink2.oracle.com/metalink/plsql/ml2_documents.showDocument?p_database_id=NOT&p_id=295626.1
If you still have any queries, please feel free to post it here.Thanks for note.. i am reading it and its soo usefull for me, thanks for sharing your knowledge here wiht us hussein..
you are an oracle angle :)
regards
Helios
Edited by: helios on 12.May.2009 06:58

Oracle SGA components manual allocation

All,
Phyical memory : 420G My database version : 11.2.0.3 running on linux machine.
Memory_target = 200G . I would like to allocate this value to following SGA components. I don't want to automatic memory management enabled. Can you please guide me how to split 200G for following components. Is there any percentage for each components ?
db_cache_size
db_recycle_cache_size
db_keep_cache_size
large_pool_size
java_pool_size
shared_pool_size
pga_aggregate_target
streams_pool_size
log_buffer
Thanks

There is no 'default' settings for the components. Oracle tell you, when you create a database with DBCA, that the values provided by that tool are for a sample database and you should tune them to how you see fit.
This is what I would do (assuming this is a test environment, of course):
- If you're using HugePages, disable it.
- Run with AMM but give some key components a 'minimum' value (such as SGA, PGA, shared_pool, etc) so it's not too crazy. Setting everything at 0 can have performance issues with some databses, strangely.
- Run an entire workload cycle (day, week, etc) - enough batch processing to mimic a realistic workload on Production
- Check out the dynamic views/AWR reports to see what the database advises with the various components.
- If you want to use HugePages, then set the SGA and PGA to whatever you've determined from the AWR reports. You can choose whether to specify minimum values for the SGA components.
- If you're not using HugePages, you really should use AMM. What I do is give the SGA and PGA minimum values and allow the database to decide which one gets the 'extra' memory that's left over. That way, the SGA doesn't drop to an impossibly small size and cause everything to crap out.
Mark

SGA+PGA Size allocation

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