Database creation - SGA size

Hi all,
When I try to create a database using DBCA, My default SGA Size : 128. PGA:794. When I click Next button, I receive the following caution...
Following parameters do not meet the recommended minimum size requirements:
An SGA size of atleast 160MB is recommended
Do you want Database configuration Assistant to Change the Parameter? I gave ignore and I changed the SGA size to: 160, I received the bellow caution
SGA Size can not be greater than maxmimum shared memory segment size (1342177728). Refer to oracle installation guide to configrue your operation system kernel parameters.
Please suggest me on the same....
Thanks
Gir

user10737570 wrote:
My other database SGA_MAX_SIZE is 1G.
Now I'm trying to create database using DBCA. By default my sga size allocated is 128MB. It recommends SGA size should be 160MB. I'm not able to extend SGA size. Please refere my previous post...
Could you please tell me why my default screen is showing as 128MB.
ThanksThe oracle installer determines the available sga_size bij calculating free "shared memory"
This is the setting of the maximum shared memory as posted in the first message minus the memory used by your first database, minus some other shared memory stuff.
To overcome this, you have to increase the mamimum shared memory size in your kernel and if needed reboot the system.
If your system happens to be a Redhat Enterprise system, then lookup the variable called
kernel.shmmax = <a certain size>
in /etc/sysctl.conf
Increase that value, and save the file ( as root )
Next run /sbin/sysctl -p to activate the new config

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Hi buddies,
I got some interview questions, might be simple for geeks in DBA. I am in need of answers. Could anyone help me.
Thanks,
Raaj
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A: No, only AIO
B: Yes, depending on hardware.
C: Yes.
D: No.
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Answer: Choose one of the answers that apply
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C: V$ROLLNAME
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information is altered in a specific way every time you log into Oracle,
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B: Creating an appropriate LOGIN.SQL file
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START WITH 394
INCREMENT BY 12
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NOCACHE
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1.-
2.c
3.a
4.a
5.c
6.b
7.a
8.d
9.b
10.a -
11.a
12.c
13.b
14.d
15.c
16.a -
17.a
18.d
19.c
20.a
21. -
22.d
23.b
24.?
hope it helps u.
Thanks
Kuljeet

How to Increase the SGA Size.

Hi Guru's
I want to Know
How to Increase the SGA Size in Database 8.1.7.4.1
My Ram Size is 6 GB
When I query the Below Script
select name, value
from v$parameter
where name in ('shared_pool_size', 'java_pool_size', 'streams_pool_size',
'log_buffer', 'db_cache_size', 'db_2k_cache_size', 'db_4k_cache_size',
'db_8k_cache_size', 'db_16k_cache_size', 'db_32k_cache_size',
'db_keep_cache_size', 'db_recycle_cache_size', 'large_pool_size');
Result
shared_pool_size     300000000
large_pool_size     0
java_pool_size     50000000
log_buffer     10485760
Please Suggest Me the How Much Value also to increase the SGA
My RAM SIZE is 6 GB
Regards
***SBJ***

SGA size on 8i is static , and for increasing the size you have to make the changes in the pfile and bounce the database
First thumb rule is that your SGA should not exceed more than 40% of your PHYSICAL RAM in oracle <= 8i version. You can go around 80% from oracle 9i onwards
http://mohamedazar.wordpress.com/2010/08/30/can-i-increase-sga-target-size-greater-than-sga-max-size/
Edited by: Amigo on Dec 18, 2010 1:31 AM

SGA Size

I will preface this by saying that this is probably a stupid question. I am pretty much an Oracle newbie, but I'm constantly trying to learn stuff. I have done a lot of reading on this topic, so I definitely have my own opinion, but everybody in my office thinks I'm crazy. So here goes...
We run a data warehouse in my shop on a server that has 6 CPUs and 12 GB of RAM, using Oracle 10.2.0.3. I was perusing our server's settings, and I noticed that the SGA was sized at 528 MB. It was not explicitly set in the parameter file, so I'm guessing that this value is calculated from the underlying pool sizes. Here's my stupid question: Isn't this not a good size for the SGA, given how much RAM we have?
Since we are a data warehouse, we should probably give ourselves a lot of RAM for the PGA's (according to Oracle's documentation). So I would like to crank up the SGA_TARGET to (at least) 4 GB and set the underlying pool sizes to 0 to let Oracle manage it all. But it's the fight of my life in my office. I am convinced that giving the SGA more RAM will increase performance.
So, am I crazy or not?

Sam, if everyone else in the office thinks you are crazy then you probably are; however, that does not mean that you are not correct in your argument.
The total amount of memory on the machine is not really a good factor for setting your SGA size. It is a limitation. The SGA size should be set based on the application load. Nevertheless the odds are good that doubling the SGA would have a measurable benefit since your machine has so much spare resource available.
Here is an idea. Take a seriies of statspack snapshots or use the AWR reports to measure the system during normal load. Then bounce the database and double the SGA. Rerun the same load and take the measurement. Compare. You ought to be able to sell this idea. When you see the benefit you can then repeat the procedure a couple of times to get up to a 2G, 3G, or 4G SGA.
Remember that your applicaiton will also need PGA and it is easy for the PGA requirements to equal or exceed the SGA requirements. At some point it may also be necessary to add another database instance (and SGA) to the machine so just because you have the memory does not mean that all of it should be put to immediate use.
HTH -- Mark D Powell --

How to decrease SGA size in oracle 9i

hi,
how to decrease SGA size .. now SGA size=400m i want to drecrease to 150m
Thanks,
Mohammed

Why do you want to do this? Is your system low on memory?
Perhaps your DB is on a laptop with
only a small amount of memory?
Well an enterprise database server set of
thread inside a complex service would need
a high powered laptop with large amounts
of memory.
Or perhaps your UAT server has 10 databases
on it all competing for resource?The culprit may not be Oracle.
For example (as you have not told us your operating system, windows linux unix?) IBM's AIX unix operating system comes configured optimally for managing file caching in the OS memory; as Oracle also caches the blocks read from disk sometimes the file system caching is redundant and ends up using memory better allocated to Oracle. In that case you tune the Unix kernel to reduce memory allocated to the file system caching. The default settings allow IBM AIX to take up to 80% of system memory for caching bad if you have allocated 40% to the SGA already.........
The really cool thing about AIX is you can do this on the fly and you don't need to reboot so when you go live you juggle until you get an optimal setting and then monitor.
In the end you may just have to add memory.

Database creation in oracle 9i

can any one tell me step of database creation in oracle 9i
i try many times from 2 days through script because my DBCA is not open
when i click it. DBCA created orcl during instalation but now
it is not running. will i have to install it ?
1)i add db_name=mukesh below db_name=orcl and run script but errors
2)i crete initm.ora by copy init.ora and change db_name=orcl by db_name=mukesh
in initm.ora but errors
1)when i use init.ora without adding db_name=mukesh
i also change undo_management by AUTO to manual i get
SQL> shutdown immediate;
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
SQL> startup pfile=D:\oracle\admin\orcl\pfile\init.ora nomount
ORACLE instance started.
Total System Global Area 135338868 bytes
Fixed Size 453492 bytes
Variable Size 109051904 bytes
Database Buffers 25165824 bytes
Redo Buffers 667648 bytes
SQL> create database mukesh
2 datafile 'D:\oracle\oradata\mukesh\system01.dbf' size 325m
3 logfile
4 group 1 ('D:\oracle\oradata\mukesh\redo01.log') size 100m,
5 group 2 ('D:\oracle\oradata\mukesh\redo02.log') size 100m,
6 group 3 ('D:\oracle\oradata\mukesh\redo03.log') size 100m;
create database mukesh
ERROR at line 1:
ORA-01501: CREATE DATABASE failed
ORA-01504: database name 'mukesh' does not match parameter db_name 'orcl'
after that i add db_name=mukesh below db_name=orcl
SQL> shutdown immediate;
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup pfile=D:\oracle\admin\orcl\pfile\init.ora nomount
ORACLE instance started.
Total System Global Area 135338868 bytes
Fixed Size 453492 bytes
Variable Size 109051904 bytes
Database Buffers 25165824 bytes
Redo Buffers 667648 bytes
SQL> create database mukesh
2 datafile 'D:\oracle\oradata\mukesh\system01.dbf' size 325m
3 logfile
4 group 1 ('D:\oracle\oradata\mukesh\redo01.log') size 100m,
5 group 2 ('D:\oracle\oradata\mukesh\redo02.log') size 100m,
6 group 3 ('D:\oracle\oradata\mukesh\redo03.log') size 100m;
create database mukesh
ERROR at line 1:
ORA-01501: CREATE DATABASE failed
ORA-00200: controlfile could not be created
ORA-00202: controlfile: 'D:\oracle\oradata\orcl\CONTROL01.CTL'
ORA-27038: skgfrcre: file exists
OSD-04010: <create> option specified, file already exists

Hi,
If you getting a problem with DBCA go for manually process:-
I had listed steps which I follow
Step 1: Decide on Your Instance's System Identifier (SID)
Step 2: Create the Initialization Parameter File
Note:- Name the copied init.ora file init<SID>.ora because this is the default naming convention that the Oracle server looks for when it tries to start up the instance ORACLE_HOME/dbs directory (exists over the prefered path)
Edit this file's parameters so that your database and your instance will run effectively on your system.
DB_NAME Must be set to a text string of eight characters or less. During database creation, the value assigned to DB_NAME is recorded in the database's datafiles, redo log files, and control files. If, when you attempt to start the database instance, the value of DB_NAME as recorded in the initialization parameter file and the database name in the control files are not the same, the database will not start.
DB_DOMAIN A text string that specifies the network domain where the database is created.
CONTROL_FILES Is assigned the comma-separated list of control file names to use for the new database. When you execute the CREATE DATABASE statement, the control files listed as values assigned to this parameter are created. If you fail to specify a filename for the CONTROL_FILES parameter, Oracle creates a file with a default operating system dependant filename.
DB_BLOCK_SIZE Specifies the standard block size of the database. This size is used in the creation of the system tablespace and by default in any other tablespaces created. Take care when determining what this value should be because after the database is created, the value cannot be changed.
UNDO_MANAGEMENT Determines whether the database starts in automatic undo management mode. A value of AUTO enables automatic undo management; MANUAL enables manual undo management mode. In 9i, AUTO is suggested, but MANUAL is default.
UNDO_TABLESPACE When the instance starts in automatic undo management mode, it needs to have a tablespace in which to store its undo information. The default is SYS_UNDOTBS and is automatically created if you execute a CREATE DATABASE statement with the UNDO_MANAGEMENT initialization parameter set to AUTO and no UNDO TABLESPACE statement in the CREATE DATABASE statement.
Step 3: Connect to and Start the Instance
Connect to the instance as SYSDBA either using operating system authentication or the password file method of authentication and start up the instance using the STARTUP command.
sqlplus '/ as sysdba'
If your parameter file is not in the default location or is not named init<SID>.ora, you may need to specify the PFILE clause in the STARTUP command for the instance to start.
Because you do not yet have a database attached to the instance, you need to start up the instance in NOMOUNT state:
startup nomount;
The instance is now started and ready for the CREATE DATABASE command.
Step 4: Issue the CREATE DATABASE Statement
create database mydb1 controlfile reuse
Logfile
Group 1 ('/mydb1/log1/log01a.log',
'/mydb2/mydb1/log01b.log') size 50M,
Group 2 ('/mydb1/log1/log02a.log',
'/mydb2/log1/log02b.log') size 50M,
Group 3 ('/mydb1/log1/log03a.log',
'/mydb2/mydb1/log03b.log') size 50M
Datafile '/mydb1/mydb1_system.dbf' 250M
AUTOEXTEND ON MAXSIZE 500M
Undo tablespace mydb1_undo1
Datafile '/mydb/mydb1/mydb1_undo1.dbf' 50M
Default temporary tablespace mydb1temp tempfile
'/mydb/mydb1/mydb1temp1.dbf' size 75M
Extent management local
Character set US7ASCII
MAXLOGFILES 10
MAXLOGMEMBERS 10
MAXLOGHISTORY 1
MAXDATAFILES 500;
Thanks
Pavan Kumar N

How to increase SGA size in Oracle 9i release 9.0.1.1.1

Hi,
We have Oracle 2000 server on a intel machine (2.8GHz processor and 2 GB RAM). Virtual memory is :- 3GB.
We have a Oracle 9.0.1.1.1 running on this machine. What are the parameters that I need to set to increase the SGA size. We want a large SGA size with enough space for shared pool.
Thanks in advance.
--Malay

Malay,
First Check out the RAM utilization for the OS Kernel and remaining to the applications and then to SGA.
We have Oracle 2000 server on a intel machine (2.8GHz processor and 2 GB RAM). Virtual memory is :- 3GB.I suppose its Windows 2000 Server!!!
& What's the size of the Database?
all these things allow you to decide how "large" you can increase the SGA

How much can go for SGA size in 32-bit Linux OS for 11i

Dear all,
I am looking for a better solution to my doubt from all the Guru's.
My requirement is that need to get minimum SGA size =10GB for my production system. At present my 11i application server and database running on Red Hat Enterprise Linux AS release 4 (Nahant Update 2) 2.6.9 42.ELsmp (32-bit) system with SGA size of 2GB with multi-node installation. Now we are planning to move from this old server to another set servers for production system with higher capacity.
Basically my requirement is that, for new server minimum SGA size=10GB in 32-bit linux OS, so please help me out to find the right solution.
Version details
RDBMS : 10.2.0.2.0 &
Oracle Applications : 11.5.10.2
thanks,
Ajikumar G

Hi,
Refer to below link that can help out
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:30011178429375
Reason for refering to link is you can get better information instead of explaning my self - I might miss some thing - just in case.
- Pavan Kumar N
Oracle 9i/10g - OCP
http://oracleinternals.blogspot.com/

Database creation error ucing DBCA

Hi!
When i istalled oracle 9i .the installation is suucessful but database creation is not.
the database creation aborted with error invalid size entry(expected 419...1232 but found 4192...1230 )
Pls Help
Hainder Kaur

Hi,
Again run database create assistance by ./dbca and choose custom option for creating database,in this option oracle run database creation's scripts and i hope this time u will not face the same problem.
Thanks
Kuljeet

Reduced SGA_TARGET, but SGA size not changing?

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

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

Altering SGA size

Hi,
We are in the process to increase the size of SGA to improve the performance of our Production Database, as its performance have been degraded.
Our database server is having total 2GB of RAM.
SGA_MAX_SIZE is not defined in the init.ora file
The following are the details of database memory structures :
Total System Global Area = 180.63088 (MB)
database buffers = 53.4921875 (MB)
shared_pool_size = 100 (MB)
large_pool_size = 0.5859 (MB)
java_pool_size = 20 (MB)
db_block_buffers = 6847 bytes
db_block_size = 8192 bytes
So how much SGA size can we increase to improve the performance of the database server?
which parameters from above are required to be altered and upto how much size ?
Kind request to provide the guidance.
Regards.

hi
this depends upon organization to organization
well just check this out the link
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/create.htm#ADMIN00207
Hope this helps
CHeers

Swapping and Database Buffer Cache size

I've read that setting the database buffer cache size too large can cause swapping and paging. Why is this the case? More memory for sql data would seem to not be a problem. Unless it is the proportion of the database buffer to the rest of the SGA that matters.

Well I am always a defender of the large DB buffer cache. Setting the bigger db buffer cache alone will not in any way hurt Oracle performance.
However ... as the buffer cache grows, the time to determine 'which blocks
need to be cleaned' increases. Therefore, at a certain point the benefit of a
larger cache is offset by the time to keep it sync'd to the disk. After that point,
increasing buffer cache size can actually hurt performance. That's the reason why Oracle has checkpoint.
A checkpoint performs the following three operations:
1. Every dirty block in the buffer cache is written to the data files. That is, it synchronizes the datablocks in the buffer cache with the datafiles on disk.
It's the DBWR that writes all modified databaseblocks back to the datafiles.
2. The latest SCN is written (updated) into the datafile header.
3. The latest SCN is also written to the controlfiles.
The following events trigger a checkpoint.
1. Redo log switch
2. LOG_CHECKPOINT_TIMEOUT has expired
3. LOG_CHECKPOINT_INTERVAL has been reached
4. DBA requires so (alter system checkpoint)

Need to Increase SGA Size

Hi,
RDBMS : 11.1.0.7.0
OS : RHEL 5 (X86_64)
EBS : 12.1.3
My Database Server RAM size is 128 gb
Currently my Parameters are
SGA_Target = 2g
SGA_max = 2g
Shared_pool_size = 600m
Kernel Parameters are :
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.sem = 256 32000 100 142
kernel.shmmni = 4096
kernel.msgmni = 2878
fs.file-max = 6553600
net.ipv4.ip_local_port_range = 1000 65000
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 262144
My question is...
As My project manager is asking to increase the SGA Size as i have 128gb RAM of server.
Maximum how much i can increase the SGA Size
It is PRODUCTION Server... Now it's running with out any issue... but so much RAM is there y can't we use....?
Please advice..
Thanks,

As per the Note
Maximum SHMMAX values for Linux x86 and x86-64 [ID 567506.1]
=======================================================================
QUESTION 2
===========
What is the maximum value of SHMMAX for a 64-bit (x86-64) Linux system?
ANSWER 2
===========
Oracle Global Customer Support officially recommends a " maximum" for SHMMAX of "1/2 of physical RAM".
The maximum size of a shared memory segment is limited by the size of the available user address space. On 64-bit systems, this is a theoretical 2^64bytes. So the "theoretical limit" for SHMMAX is the amount of physical RAM that you have. However, to actually attempt to use such a value could potentially lead to a situation where no system memory is available for anything else. Therefore a more realistic "physical limit" for SHMMAX would probably be "physical RAM - 2Gb".
In an Oracle RDBMS application, this "physical limit" still leaves inadequate system memory for other necessary functions. Therefore, the common "Oracle maximum" for SHMMAX that you will often see is "1/2 of physical RAM". Many Oracle customers chose a higher fraction, at their discretion.
Occasionally, Customers may erroneously think that that setting the SHMMAX as recommended in this NOTE limits the total SGA. That is not true. Setting the SHMMAX as recommended only causes a few more âshared memory segmentsâ to be used for whatever total SGA that you subsequently configure in Oracle. For additional detail, please see Document 15566.1, "SGA, SHMMAX, Semaphores and Shared Memory Explained"
==========================================================================
Our server RAM is 128 gb.... as per the note 1/2 of the physical RAM we can assign for SHMMAX parameter... (apprx 60gb)
How can i understood this answer for my configuration......
Please advice...
Thanks,

ORACLE SGA size

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
jeevan

Hi 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

Increase the SGA size!

Hi,
We are using EBS 12.0.6 and DB 10.2.0.3.
Currentlly My SGA is 2 GB and we have 8 GB of RAM, and Swap area is 10 GB.
Please recommemded us to SGA size and related DOC ID.
thx.

Hi again;
In addition to my previous post also check
Oracle Database 10g Automated SGA Memory Tuning Doc ID: 257643.1
How To Use Automatic Shared Memory Management (ASMM) In Oracle10g Doc ID: 295626.1
Hope it helps
Regard
Helios

Database creation - SGA size

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