Kernel para and sga,pga sizing

Hello,
OS-HP-UX(configured to use high sga /no restrictions)
Current database is running without any issue
Due to increase in physical ram i plan to increase sga and pga(ram is increase about 3 times)
My question:
1)should i also increase sga and pga in same propotion (3 times then existing)
or use 70% ROT formula
2)whatever figure i arrive by analysis for increasing sga,do i need to change kernel parameters also
(does i requre to change kernel parameter every time ram and sga is increased)
Please suggest
Thanks

880991 wrote:
Ok some questions based on your reply:
1)then how any gain in upgrading memory above 4 GB if shmmax cannot be more then 4 GB (32 bit OS),then
SGA also cannot be > 4GB (As per documents SHMMAX should be > SGA)Because the SGA doesn't have to be in one segment. Which version of Oracle are you looking at? It makes a difference!
http://kevinclosson.wordpress.com/2009/07/27/little-things-doth-crabby-make-part-x-posts-about-linux-hugepages-makes-some-crabby-it-seems/
>
2)I read if Operating system is linux can use SGA above 4GB,in fact one of friend told they implemented SGA
4GB on linux configuring VLM/Huge pages,so in that case ( VLM ) needs to set SHMMAX > 4GB (as per memory ROT) of VLM take cares of SGA > 4GB even if SHMMAX is not setintrestingly my friend also mentioned that in there server VLM is set and shmmax is set < 4 GB and SGA > 4GB
still it works without problem when checking SGA usage in dyanamic views its shown as using above 4 GB
,it contradicts what i read in documents,how this is working ,anyone have idea?[url http://download.oracle.com/docs/cd/B28359_01/server.111/b32009/appi_vlm.htm]No contradiction.
Also VLM implementation is restricted to Linux or it can be on set on Unix as well and if its set do all components
of SGA benefit or only buffer cache?
ThanksIt varies, some unix are quite different than others. Specific answers can only be given to specific configurations. I really have to wonder when you are asking about hp-ux and 32 bit.

Similar Messages

Size of Kernel parameter and SGA

Hi,
Can you please suggest me the ideal size of kernel parameters and SGA?
Currently, I have installed 2GB RAM on my machine using Oracle 10.1 database version on Fedora Linux platform. The parameters are currently set as below:
kernel.shmall = 2097152 (2MB)
kernel.shmmax = 2147483648 (2048 MB)
kernel.shmmni = 4096
# semaphores: semmsl, semmns, semopm, semmni
kernel.sem = 250 32000 100 128
I will appreciate if you can give me an idea about the proper size of SGA including SHARED_POOL_SIZE,LARGE_POOL_SIZE AND JAVA_POOL_SIZE.
Thanks in advance.
Jayesh

Oracle's install docs indicate practical minimums. The specific section for Linux x86 is at
http://download-west.oracle.com/docs/cd/B19306_01/install.102/b15660/pre_install.htm#sthref264
The proper size of the pools is always dependent on the workload. It takes experience, understanding of the application and monitoring to size these properly - the realm of the DBA.
However, by setting the SGA_TARGET to some value (less than equal to SGA_MAX_SIZE) and setting these three parameters to '0', the system will use an effective compromise that dynamically changes based on workload.
My suggestion is that the SGA_TARGET and the PGA_AGGREGATE_TARGET be set to ensure the system does not start swapping - when considering all the other normal memory requirements on the system.

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

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

Change a size of PGA and SGA

Hi,
I have a plan to increase size of PGA and SGA. Please recommend me which metric in Statspack report I should monitor to check what is the impact of such change.
Best.

Hi Lesak;
Please check below 2 thread:
How we size SGA
Re: Estimating SGA Size
SGA and PGA size
SGA and PGA size
Regard
Helios

SGA, PGA and SHMMAX Setting

If I have set SHMMAX to 8GB (on 64bit linux) value, does that mean that my SGA+PGA values need to remain within 8GB limit? If my SGA size is 6GB and PGA size is 4GB, does that mean that my OS is going to allocate two shared memory segments?

The SHMMAX parameter is used to define the maximum size (in bytes) for a shared memory segment and should be set large enough for the largest SGA size.
http://www.idevelopment.info/data/Oracle/DBA_tips/Linux/LINUX_8.shtml
http://books.google.co.in/books?id=2ImPFP6Yk64C&pg=PA357&lpg=PA357&dq=PGA+is+included+in+SHMMAX&source=bl&ots=On3S7-CEX0&sig=LhOYOO946hrPZh-cIUEzWNiwpRg&hl=en&ei=xyLOTJqaC4yYvAONm7T3Dw&sa=X&oi=book_result&ct=result&resnum=5&ved=0CCwQ6AEwBA#v=onepage&q&f=false
Please close the thread as answered.

Difference between UGA, PGA and SGA in oracle

please tell me what is the difference between UGA, PGA and SGA in oracle in the simple layman language
thanx in advance

UGA
The User Global Area (UGA) is a memory area (RAM) that holds session-based information.
Shared Server Area
When running in [[Shared Server]] mode (MTS with shared servers and dispatchers), sessions can be served by multiple server processes. As a result, the UGA cannot be stored in the [[PGA]], and is moved to the [[SGA]] (shared global area).
Dedicated Server
When running in [[Dedicated Server]] mode (one session = one dedicated process), the UGA is stored in the [[PGA]] (process global area).
i have question......
how to check and monitor the cpu usage ,temporary and memory usage in db?
ple could any body explain me.................
Edited by: 821205 on Dec 20, 2010 7:59 AM

Stream Pool Sizing and SGA AMM

Hi DBAs,
Just a very general question. I have enabled the SGA AMM. So the Stream Pool Size is not defined. Sometime I am getting the warning for messages are spilling over. Should I increase the SGA or Disable the Automatic Memory Managent and define the Stream Pool Size explicitly. I am using Oracle 10.2.0.4 (single instance). I have heard from some experts that SGA AMM feature doesn't scale well some time but not sure how it manage the streams pool. If SGA AMM is not enabled then SGA only allocate 10% for Stream Pool. Total System RAM is 16GB and SGA Max and Target is 8 GB.
Should I increase the SGA AMM enabled or explicitly define the Stream Pool Size? Any suggestion please ..
Regards
-Samar-

When you set SGA_TARGET, normally the value of STREAMS_POOL_SIZE is 0 and AMM allocate memory as needed by the system.
Nevertheless, if you set it, then it means you request the minimum value for streams_pool_size not to shrink below this value.
You did not precise if the spilling occurred on Source or on Target.
-On source, it means that the messages are not propagated fast enough (usually this is paired with flow control in effect) and the excess messages are spilled to disk queue table.
-On Target, it means the apply process is not fast enough, and messages received in the buffered queue table are spilled onto the disk queue table (your aq$_<queue_name>_P)

SGA/PGA best practice

With an XE limitation of 1GB for the PGA and SGA, how would one best preserve this limitation?
In other words, how would one minimise the PGA and SGA usage via ones interface with Oracle?
For instance, in a SQL query I was building I could either (The query has multiple aggregates on multiple tables in a 'one to many' join relationship):
1) Use WITH clauses
2) Use inline views
3) Use standard views
4) Use temporary tables
5) Maybe more possibilities
Without much of an insite into how Oracle 'works' it's difficult to gauge which of these is less 'resource hungry'.
Possibly there is a reference on how to use the PGA & SGA efficiently?
Or possibly a more definitive explanation on what's actually stored in these memory areas (rather than just 'prorgam' and 'system' data).
Regards all,

SGA is used in 2 main areas: parsing the SQL and avoiding disk reads by having stuff in memory. There is one SGA for all of XE instance.
PGA is used heavily for sorting, hash joining and 'working stuff'. The PGA is created for each Dedicated Server process. Much of the PGA is inside the SGA for Shared Server processes
SGA: (There are exceptions to each of these 'Rules Of Thumb' or 'ROT' statements)
Good coding technique will allow reuse of SQL and avoid as much as possible reparsing;
Use bind variables;
Do not create SQL on the fly;
Avoid dynamic SQL (concat strings to create SQL on the fly);
Forget about tweakiing the buffer cache as it is mainly a performance thing that you can't do much about in XE;
WITH clause is nice as it may reduce the count of subqueries;
Leave it with 'automatic memory management' (again a perf hit, but it will attempt to optimize mem availability);
Don't reinvent - Use the features that are loaded as they will likely get statements out faster, releasing memory faster;
Stored Views may (often do) grab unneeded table data. When joining to stored views, see whether they can be replaced by cleaner code;
Do not create SQL on the fly.
PGA:
Use shared server when feasible (at risk of performance hit);
Global Temp Tables go into PGA, watch the use;
Maximize reuabale SQL, minimze all other languages (remote or in DB) including PL/SQL;
Watch for PGA wasters such as UNION vs the better UNION ALL, and unneeded sorts;
PGA is 'swapped out' to Temporary tablespace. Make sure temp tablespace big enough ... it's not counted in the 4GB disk;
Avoid using COMMIT except at end of transaction. Avoid COMMIT in loops. Make sure undo tablespace is big enough ... it's not counted in the 4GB disk ;
Did I mention it's not a good idea to create SQL on the fly?

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;

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

AWR SGA+ PGA usage

Hi
We're doing some performance testing on our database. The SGA is set to 1.5GB and PGA set to 0.5GB. At some point we are runnning out of memory as we ramp up the number of users and transactions .
What I'm looking for is to graph the PGA and SGA usage seperately regular intervals (a line graph) showing their increaase as users ramp up.
Anyone any ideas on how I can get this information whether through AWR or manually.
Thanks in advance.

You have not posted the version you are on. You should use automatic pga management and unset the values for areasize parameters (if there is no specific reason for keeping them).
ORA-04030: out of process memory when trying to allocate 8389132 bytes (pga heap,redo read buffer)
Doing block recovery for file 3 block 76812
Resuming block recovery (PMON) for file 3 block 76812What are the OS level statistics of memory usage ?
It simply means that Oracle (rather OS...as Oracle is also going to request memory from OS only) is running out of memory. Most common reason behind that is use of features like bulk collect without any limit clause which causes the pga memory to grow beyond pga_aggregate_target...and finally sucking all the memory available. Further requests for memory allocation start failing with ORA-04030.
Also, please post the output from v$pgastat using tags.
Edited by: amardeep.sidhu on Nov 24, 2010 9:29 AM

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

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 concept

We have a production Oracle 11g DB in which SGA_TARGET is 0 but ASSM is enabled but the documentation on Oracle says that if SGA_TARGET is 0 means that ASSM is disabled. Also, PGA_AGGREGATE_TARGET is 0 but Maximum PGA allocated is around 1 GB.
I hope, my question is clear that concept seems to be confusing where SGA_TARGET is 0 but ASSM is enabled and also PGA_AGGREGATE_TARGET is 0 but maximum PGA allocated is 1 GB.
Please revert with the reply to my query.
Regards

972145 wrote:
Thanks for your reply but there is some confusion. ASMM is automatic shared memory management which seems to be similar to AMM which is automatic memory management. ASMM can be seen from OEM under Database Configuration->Memory Advisors. I guess, there is ASM which is automatic storage management to do with reduntant copies of data to provide fault tolerance.
ASMM - 10g setting for the automatic SGA using the parameter sga_target .
AMM - 11g setting for both SGA and PGA, uses the parameter memory_target
ASM - Automatic Storage Management, nothing to do with SGA or PGA
ASSM - Automatic Segment Space Management, for the tables and nothing to do with the PGA and SGA
Aman....
Edited by: Aman.... on Jan 21, 2013 3:53 PM corrected the typo

Kernel para and sga,pga sizing

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