SGA_MAX_TARGET and SGA_TARGET

What is difference b/w these two parameters ?
If SGA_TARGET= 10G
SGA_MAX_TARGET=15G
Which parameter will be used during startup and Why ?
Any refernce doc aur explanation will be helpful
Regards
Sourabh Gupta

Sourabh85 wrote:
On Windows XP and db version 10.2.0.4
I set the SGA_TARGET=500M and SGA_MAX_SIZE= 1024M.
Started the db and db is started with SGA =1G which means SGA_MAX_SIZE
SQL> show parameter sga
NAME TYPE VALUE
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 1G
sga_target big integer 500M
SQL> show sga
Total System Global Area 1073741824 bytes
Fixed Size 1293588 bytes
Variable Size 696255212 bytes
Database Buffers 369098752 bytes
Redo Buffers 7094272 bytes
So still the question is what is advantage of setting both parameter in pfile.
I think the above behavior is related to Windows only.
Regards
Sourabh GuptaYou've set it in pfile but the database will read the spfile by deafault..
So first you need to check if the database is reading from spfile or pfile..
show parameter spfileif it returns any value then the database is using spfile
if it doesn't return any value the it is using pfile...

Similar Messages

Difference between SGA_MAX_SIZE and SGA_TARGET

Difference between SGA_MAX_SIZE and SGA_TARGET

user8645026 wrote:
Difference between SGA_MAX_SIZE and SGA_TARGETIs discussed in the database forum, not the forum for which the title is " Community Feedback and Suggestions (Do Not Post Product-Related Questions Here)".
Is also discussed in the documentation at http://tahiti.oracle.com

Log Buffer and SGA_target

Hello,
What should be the best sizing for an Oracle db 10g, windows server 2003, 4gb ram + 2 processors, process over 5 mills records a day, using sqlldr, many pls, etc.
Now it has 100m log_buffer and sga_target 612m, but it´s very low and per each second generates log files, till 2 -3 log files per second, the size of each file is 5m.
Please help, I would like it to generate log files per each hour. Please let me know the combination of parameters that I would have to change.
Thanks in advance,
Juan Angel

Mark,
I installed the DB, in fact, I am not a DBA, I am in charge of the revenue assurance department for a Telco company, I do not know that much about setting up a DB, I used to be an oracle analyst only.
How do I resize them?, the manual says about improving the checkpointing, there are two parameters of checkpointing: log_checkpoint_interval=0 seconds, and log_checkpoint_timeout=1800 seconds, 30 minutes, down some parameters of the spfile:
__db_cache_size = 343932928
__java_pool_size = 8388608
__large_pool_size = 20971520
__shared_pool_size = 134217728
background_dump_dest = D:\ORACLE\PRODUCT\10.1.0\ADMIN\RA\BDUMP
compatible = 10.1.0.2.0
control_files = ('D:\ORACLE\PRODUCT\10.1.0\RA\U02\ORADATA\RA\CONTROLFILE\O1_MF_1K9O0R7F_.CTL', 'D:\ORACLE\PRODUCT\10.1.0\RA\U03\ORADATA\RA\CONTROLFILE\O1_MF_1K9O0R9V_.CTL')
core_dump_dest = D:\ORACLE\PRODUCT\10.1.0\ADMIN\RA\CDUMP
db_block_size = 8192
db_create_file_dest = D:\oracle\product\10.1.0\ra\u01\oradata
db_create_online_log_dest_1 = D:\oracle\product\10.1.0\ra\u02\oradata
db_create_online_log_dest_2 = D:\oracle\product\10.1.0\ra\u03\oradata
db_domain = 'megatel.hn'
db_file_multiblock_read_count = 8
db_name = ra
db_recovery_file_dest = D:\oracle\product\10.1.0\ra\flash_recovery_area
db_recovery_file_dest_size = 30536091648
dispatchers = '(protocol=TCP)'
job_queue_processes = 10
log_archive_dest_1 = 'LOCATION=D:\oracle\product\10.1.0\ra\flash_recovery_area'
log_archive_format = 'ARC%S_%R.%T'
log_buffer = 100000256
open_cursors = 300
pga_aggregate_target = 203423744
processes = 150
remote_login_passwordfile = EXCLUSIVE
sga_target = 612368384
sort_area_size = 65536
undo_management = AUTO
undo_tablespace = UNDOTBS1
user_dump_dest = D:\ORACLE\PRODUCT\10.1.0\ADMIN\RA\UDUMP
I appreciate your helping me.
Juan Angel

Issue creating a database: SGA_MAX_SIZE and SGA_TARGET

Hello:
While creating a custom database, I am running into issues with the values I specify for SGA_MAX_SIZE and SGA_TARGET.
The install manual for the product I am creating the database for says that SGA_MAX_SIZE should be >= SGA_TARGET_SIZE. It also wants a minimum of 1Gig for SGA_Target
The Database Configuration Assistant defaulted to 0.64GB for SGA_TARGET and 0.168 for SGA_MAX_SIZE (This is clearly against the instruction in the installation manual).
Who is right? Me or the vendor?
I read some threads that indicate that the vendor may be wrong.
venki

Follow the vendor's instructions.
DBCA has never in its existence made a correct decision yet. It puts all control files and redo logs into one directory.
It doesn't create multiple members for the log file groups.
And its memory management is based on a simple algorithm that has nothing to do with any specific reality.
DBCA is intended for creating a generic database for generic purposes ... and that it does very very well.

Increase the SGA_MAX_SIZE and SGA_TARGET parameters

HI ,
I am using oracle 10g R2 and windows server 2003 .
My server is having 8 GB RAM .
I want to increase the SGA_MAX_SIZE and SGA_TARGET parameters .
I am using the below command , but getting the error
SQL> alter system set sga_max_size=2000M scope=spfile ;
alter system set sga_max_size=2000M scope=spfile
ERROR at line 1:
ORA-32001: write to SPFILE requested but no SPFILE specified at startup
Can someone please help ..

hi
connect as sys user and then try...
first make folder as backup and then copy the old SPFILEorcl to the same folder(backup)
now you can easily modify the files otherwise you will get error..
you will find here..
C:\ORACLE_HOME\database
SQL> alter system set sga_max_size=2000M scope=spfile ;
System altered.OR.
connect as sys user.
and do the following...
1).SQL>create pfile from spfile;
2).modify the pfile and decrease\increase the size of pools.
3).shutdown database.
4). Startup database using created pfile.
if it start ok then.
5.) Recreate the Spfile with the created Pfile.
SQL>create spfile from pfile;sarah

Increase SGA_MAX_SIZE and SGA_TARGET

Hi all,
I want to increase SGA_MAX_SIZE and SGA_TARGET in 10g. Currently we have
SQL> sho parameter sga
NAME TYPE VALUE
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 2384M
sga_target big integer 2384M
And we have 16GB RAM in redhat linux 4(32 bit).Oracle 10.2.0.3 DB.
Because of 32 bit OS, I was not able to increase shmmax more than 4GB.
In this situation how and how much SGA_MAX_SIZE and SGA_TARGET I can increase?
Thanks in Advance,
Sunil

Hi sunilgln,
Given the present state of things, you have to take a meassure of how many RAM is used with nothing running but the OS, that will give you the Linux footprint.
Take note of the amount of physical free memory (using top command)
Later you have to estimate how much swapping are you willing to accept, the SGA you define may be within the ranges of
FREE MEM*90% and FREE MEM*90+(OS FOOTPRINT*%SWAP MEMORY WILLING TO USE)
This is a proposal for setting this up, you need to tune and balance load depending on usage.
Another recommendation, SGA_TARGET is dynamic, SGA_MAX_SIZE is not...but you may set SGA_MAX_SIZE to a full allocation and set SGA_TARGET to a percentage that allocation and gradually use it.
What happens is: the OS will "allocate" a chunk(or chunks) the size given by SGA_MAX_SIZE, but the real usage by the database will be determined by SGA_TARGET.
Hope this helps you
Ignacio
Regards
http://oracledisect.blogspot.com

SGA_MAX_SIZE and SGA_TARGET how to set minimum for pools

Hello, we are on 10.2.0.4, Solaris 5.10. We are using ASMM, so SGA_TARGET and SGA_TARGET size are set. Hence, buffer cache, shared pool, large pool and java pool are automatically sized. However, we do not have any minimum values for those. How do I determine what this minimum value should be?
thank you!

HI,
Yes you need size the minimum value for shared pool, buffer cahce tec... else it will start consuming wholeThe documentaion
states:
You need not set the size of any of these components explicitly. By default the parameters for these components will appear to have values of zero. Whenever a component needs memory, it can request that it be transferred from another component by way of the internal automatic tuning mechanism. This transfer of memory occurs transparently, without user intervention.Can you please explain how would it start consuming the entire SGA?

Sga_max_size and sga_target values

I have an 11g database on windows with 4GB RAM, I have set the MEMORY_MAX_TARGET and MEMORY_TARGET, what should I do with the pre-existing sga_max_size and sga_target values

memory_target = sga_target + max(pga_aggregate_target, maximum PGA allocated)
MEMORY_MAX_TARGET = sum of the SGA and instance PGA sizes.
For Automatic memory management
set
ALTER SYSTEM SET SGA_TARGET = 0;
ALTER SYSTEM SET PGA_AGGREGATE_TARGET = 0;
Note:
In a text initialization parameter file, if you omit the line for MEMORY_MAX_TARGET and include a value for MEMORY_TARGET, the database automatically sets MEMORY_MAX_TARGET to the value of MEMORY_TARGET. If you omit the line for MEMORY_TARGET and include a value for MEMORY_MAX_TARGET, the MEMORY_TARGET parameter defaults to zero. After startup, you can then dynamically change MEMORY_TARGET to a nonzero value, provided that it does not exceed the value of MEMORY_MAX_TARGET.
Note:
The preceding steps instruct you to set SGA_TARGET and PGA_AGGREGATE_TARGET to zero so that the sizes of the SGA and instance PGA are tuned up and down as required, without restrictions. You can omit the statements that set these parameter values to zero and leave either or both of the values as positive numbers. In this case, the values act as minimum values for the sizes of the SGA or instance PGA.
Reference

SGA_MAX_SIZE and SGA_TARGET

DBAs,
can any one tell me in brief how SGA_MAX_SIZE and SGA_TARGET helps to tune the instance?
i have gone through with vairous link but still confuse.
Regards,
BK

hi BK,
SGA_MAX_SIZE is the maximum sizeof the shared global area (system global area), and SGA_TARGET is set when you want to use ASSM (automatic shared memory management) which is a 10g feature.
You are alos adviced to post oracle version and os.. SGA_TARGET when set, then oracle automatically manages the memory and if not set then you have to set SGA_MAX _SIZE and manually set others memory components accordingly and tune them.
I hope this helps you in a small manner
Thanks and Regards
VD

SGA_MAX_SIZE and SGA_TARGET in Oracle 10G

We have the following H/W with Solaris 9
SPARC-IV 16 CPUs
32GB RAM
128GB swap
What is the optimal size of sga_target and sga_max_size that can be configured for a heavy batch processing oracle server. Nothing runs except oracle in the above server.
We have currently 3GB SGA size , however our heavy queries are very slow.
We have huge updates on tables with more than 200Millions rows.
Do we need to have JAVA_POOL if the java stored procedure are NOT used.
However we are connecting to this database using JDBC also.
Moreover ASM is enabled in this server.
You expert suggetions are always welcome.

That's not a question that can be answered easily. It depends very much on where the time is going. Three main targets:
Writing the log file - which is largely about use of disks, not memory.
Reading data - lots of single block reads suggest looking at a bigger cache
Reading and writing temp because of large sorts/hash joins - pga configuration
One difficulty with TEMP is that the I/Os are often asynchronous, so a session can do a lot of TEMP I/O without recording much time - which means it can cause a problem elsewhere without suffering a problem itself.
You didn't mention the pga_aggregate_size - which is an important consideration in 10g and can be more important than the sga sizing in DSS and batch-like processing. Between them, the SGA and PGA_aggregate_target should probably account for a very large fraction of your memory - but (since you are on Solaris) make sure you look into large memory pages and intimate shared memory, otherwise you may need to leave a lot of memory available for the O/S memory management mechanisms.
As far as the java pool is concerned, check v$sgastat for pools which constantly show free memory, and reclaim any large free volumes.
Bottom line - if you've got the memory in the box, you might as well use it in the best possible place; but at the moment we don't have enough information to tell us where it would be most useful.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk

Relative size of sga_max_size and sga_target to the physical memory

Dear Experts,
I have installed oracle 10.2.0.4 on AIX 5.3 with 32 GB of physical memory.
Let us say other applications on the server consume 10 GB of physical memory.
Now how should i plan the size of SGA_TARGET and SGA_MAX_SIZE on the same.

As per Oracle® Database Performance Tuning Guide 10g Release 2 (10.2):
You must then divide the resulting memory between the SGA and the PGA.
For OLTP systems, the PGA memory typically accounts for a small fraction of the total memory available (for example, 20%), leaving 80% for the SGA.
For DSS systems running large, memory-intensive queries, PGA memory can typically use up to 70% of that total (up to 2.2 GB in this example).
Good initial values for the parameter PGA_AGGREGATE_TARGET might be:
For OLTP: PGA_AGGREGATE_TARGET = (total_mem * 80%) * 20%
For DSS: PGA_AGGREGATE_TARGET = (total_mem * 80%) * 50%
where total_mem is the total amount of physical memory available on the system.
(http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14211/memory.htm#i49320)

Diffrence Between SGA_TARGET and SGA_MAX_SIZE

Can Any one explain me what is the diference between
SGA_TARGET and SGA_MAX_SIZE
Thanks In Advance.

sga_max_size -- This parameter sets the hard limit up to which sga_target can dynamically adjust sizes. At database start time, Oracle will allocate sga_max_size in RAM (or set sga_max_size to the sum of the existing pool sizes), so in order not to waste RAM it may be a good idea to have sga_max_size and sga_target at the same value, but there may be times when you want to have the capability to adjust for peak loads. By setting this parameter higher than sga_target, you allow dynamic adjustment of the sga_target parameter.
sga_target -- This parameter is new in Oracle Database 10g and reflects the total size of memory footprint a SGA can consume. It includes in its boundaries the fixed SGA and other internal allocations, the (redo) log buffers, the shared pool, Java pool, streams pool, buffer cache, keep/recycle caches, and if they are specified, the non-standard block size caches.

Am I understanding SGA_TARGET and SGA_MAX_SIZE correctly?

Let's say I set SGA_MAX_SIZE to 1024MB and SGA_TARGET to 512MB.
As I understand it, this means that the total SGA size will never exceed 1024MB (that's the "hard cap"). Oracle will try to keep things around 512MB, but may burst up to 1024MB as needed.
Is that correct? Otherwise, I don't see the point of SGA_MAX_SIZE vs. SGA_TARGET.
BTW...I know MEMORY_TARGET and MEMORY_MAX_TARGET are the new 11g params, but Oracle ships XE with those turned off and the 10g SGA_* params and PGA_AGGREGATE_TARGET set...?

Hi,
In Oracle 11g MEMORY_TARGET is for automatic SGA and PGA management.MEMORY_MAX_SIZE is the maximum size to which your MEMORY_TARGET can be allocated.As shown below:
SQL> show parameter %MEMORY%
NAME TYPE VALUE
hi_shared_memory_address integer 0
memory_max_target big integer 1G
memory_target big integer 1G
But,When it comes to managing various other memory component like shared_pool,large_pool,Db_buffer_cache,log_buffer_cache,java_pool we still have to manage SGA_TARGET.
SQL> show parameter %SGA%
NAME TYPE VALUE
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 1G
sga_target big integer 0
Best regards,
Rafi.
http://rafioracledba.blogspot.com/
Edited by: Rafi (Oracle DBA) on Jun 22, 2011 11:54 PM

Ora-00604:error occurred at recursive SQL level 1 and Ora-04023

hi all
i am using oracle linux 5.5 and oracle Database 11g R2 while shutingdown the database i am getting
the following errors.
SQL> shutdown immediate;
Ora-00604:error occurred at recursive SQL level 1
Ora-04023: object select count(*) from reg$SQL>plz can anyone help me out?

Couple of questions related to this issue:
1.Is there anything in alert log. Post last 50 lines from alert log.
2.Is there any trace / log generated by Oracle ?
3.What is Memory_Target parameter value ?
4.What is value of statistics_level parameter ?
5.Did you perform any failed upgradation ?
6.Are there any invalid objects in database ?
Generally ORA-00604 is related to insufficient size of shared pool. Now, i am googling how to get a proper value of shared pool size ? I got that there is a view v$shared_pool_advice which will tell me the answer of this question. Ok, it means now question is how do i get the proper value of shared pool from v$shared_pool_advice; i mean how do i interpret this v$shared_pool_advice view ?
No problem docs are there to answer this question : (How i got this link ? Open a new page---http://tahiti.oracle.com---selected 11.2 docs--in the left hand sided there is a search text box i entered v$shared_pool_advice and i got couple of links)
http://download.oracle.com/docs/cd/E11882_01/server.112/e17110/dynviews_3037.htm#REFRN30239
I will read these links and now i will query this and DBA_HIST_SHARED_POOL_ADVICE views, interpret the values. Ok, but what about my original question i.e. ORA-00604 and 4023 ? If i am at this stage, understood all the values, it means now i can understand the meaning / sense of resizing of shared pool.
ALTER SYSTEM SET statistics_level=TYPICAL SCOPE=SPFILE;
You can monitor V$SGA_RESIZE_OPS to identify the range of values that Oracle is automatically resizing the DB_CACHE_SIZE and SHARED_POOL_SIZE components to. Then, pick an appropriate minimum value based on the range. There's no "magic formula". But V$SGA_RESIZE_OPS shows the sizes that Oracle has been automatically been resizing the SGA components to. The Buffer Cache Advisory section of the AWR report or V$DB_CACHE_ADVICE, V$SHARED_POOL_ADVICE, V$SGA_TARGET_ADVICE and DBA_HIST_SGA_TARGET_ADVICE are views that provide advisory information as well. Hemant @ SGA_MAX_SIZE and SGA_TARGET how to set minimum for pools
So, these are the baby steps if i ever gets ORA-00604 and ORA-04023 on my test database. Do all these and feel free to post the next doubt, i am sure you will get the correct answer.
Regards
Girish Sharma

User I/O and db file parallel read is high in AWR report

Hi,
We have one performance issue during a job execution.
From the awr report we have identified one query with a table having millions of records causing problems and then we had also fine tuned that query by changing it's code and by using the optmizer hints. It is being executed in plsql batches. After fine tuning, On the first batch execution(first 5000 records) the query is taking only 5 mins, but on the consecutive batches it is consuming more time( more than 30 mins).
From the awr report I got the statistics as
Release : 11.2.0.2.0
Instance Efficiency Percentages (Target 100%)
Buffer Nowait %: 100.00 Redo NoWait %: 100.00
Buffer Hit %: 85.44 In-memory Sort %: 99.98
Library Hit %: 99.76 Soft Parse %: 99.15
Execute to Parse %: 88.91 Latch Hit %: 100.00
Parse CPU to Parse Elapsd %: 87.32 % Non-Parse CPU: 98.65
The buffer hit % is good. On each batch execution it is taking different set of records.
Top 5 Timed Foreground Events
Event Waits Time(s) Avg wait (ms) % DB time Wait Class
db file parallel read 120,485 42,540 353 89.60 User I/O
DB CPU 3,794 7.99
db file sequential read 145,074 606 4 1.28 User I/O
db file scattered read 70,030 556 8 1.17 User I/O
direct path write temp 12,423 21 2 0.04 User I/O
So the I/O is our main concern since that query contains one table with millions of records.
Host CPU (CPUs: 24 Cores: 24 Sockets: 4)
Load Average Begin Load Average End %User %System %WIO %Idle
1.40 1.45 0.6 0.3 3.7 99.0
Load is also normal.
From the Time model statistics , sql execute elapsed time is 98.27% of db time and only 7.99% is that of DB CPU.
Memory Statistics
Begin End
Host Mem (MB): 64,318.0 64,318.0
SGA use (MB): 30,720.0 30,720.0
PGA use (MB): 488.2 497.1
% Host Mem used for SGA+PGA: 48.52 48.54
Both the size of sga_max_size and sga_target are 32,212,254,720(32gb) bytes and that of
pga_aggregate target is 629,145,600(600mb)
from this it is evident that the memory is still available(so increase in memory size is not an option).
The sql statistics for that query shows like that
Elapsed Time (s) Executions Elapsed Time per Exec (s) %Total %CPU %IO SQL Id SQL Text
44,950.03 55 817.27 94.67 6.99 94.72 79dgmrxh4kv74 SELECT /*+ index(cdr_data cdr_...
I can't understand whether the problem is in the database side or with the query?
If the problem is with the query, then how it has been executed in 5 mins for the first batch ?
(all the batches are having 5000 records each).
And how can we reduce the db file parallel read ?
Your valuable advice will be greatly appreciated.
Thanks in advance
Manoj Kumar N

"db file parallel read" is likely to be associated with something like index prefetching.
See:
http://www.freelists.org/post/oracle-l/RE-Calculating-LIOs,11
http://aprakash.wordpress.com/2012/05/29/index-range-scan-and-db-file-scattered-read-as-session-wait-event/
http://jonathanlewis.wordpress.com/2006/12/15/index-operations/
Tune the SQL.
Review the execution plan.
Check whether the statistics are accurate.
Review whether the index hint (and others that we can't see) is appropriate.

SGA_MAX_TARGET and SGA_TARGET

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