Setting sga_target in Oracle10g using spfile in Window OS

Question

Hi all
Previously we used to set the parameter values thru initora
Now we wish to follow the default spfile for parameters as provided by Oracle.
When we give
alter system set pga_aggregate_target = ???M;
it works properly but the same syntex does not work properly for'
processes as well as sga_target
1. Kindly guide the exact syntix to set these parameters
2. Also advise whether setting sga_target would be sufficient or do we need to set sga_max_size also and possible advantage
3. Role of Oracle Processes and what should be the ideal number for Live installation with say 100-150 simultaneous users. RAM available is enough say 8GB.
Suresh Bansal

Answer 1

Suresh Bansal wrote:
Hi all
Previously we used to set the parameter values thru initora
Now we wish to follow the default spfile for parameters as provided by Oracle.
When we give
alter system set pga_aggregate_target = ???M;
it works properly but the same syntex does not work properly for'
processes as well as sga_target
1. Kindly guide the exact syntix to set these parameters
2. Also advise whether setting sga_target would be sufficient or do we need to set sga_max_size also and possible advantage
3. Role of Oracle Processes and what should be the ideal number for Live installation with say 100-150 simultaneous users. RAM available is enough say 8GB.
Suresh BansalBoth SGA_MAX_SIZE and PROCESSES are parameters that cannot be changed dynamically, because you have omitted the SCOPE= clause of ALTER SYSTEM it takes it's default of BOTH. SGA_TARGET is modifiable in memory, but only up to the limit specified by SGA_MAX_SIZE which defaults to whatever you have SGA_TARGET set to, this means in a default setup you can only reduce SGA_TARGET. From my system
SYS @ DB10G >show parameter SGA_
NAME                                 TYPE        VALUE
sga_max_size                         big integer 584M
sga_target                           big integer 584M
SYS @ DB10G >SELECT NAME,ISSYS_MODIFIABLE
  2* FROM V$PARAMETER WHERE NAME LIKE 'sga%'
SYS @ DB10G >/
NAME                                                                             ISSYS_MOD
sga_max_size                                                                     FALSE
sga_target                                                                       IMMEDIATESo I have 584m set for both as a result I can reduce the size, but not increase it.
SYS @ DB10G >alter system set SGA_TARGET=600M;
alter system set SGA_TARGET=600M
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-00823: Specified value of sga_target greater than sga_max_size
SYS @ DB10G >alter system set SGA_TARGET=400M;
System altered.But I can set it in the spfile.
SYS @ DB10G >alter system set SGA_TARGET=600M SCOPE=SPFILE;
System altered.You only need to set SGA_TARGET, but if you set SGA_MAX_SIZE larger you give yourself room for growth later. This should be clear from the demo above.
PROCESSES controls the size of Oracle's internal process table (externalized as v$process) which is why you can't dynamically reset it, you'll need more entries in this process table than you anticipate user sessions, generally about 15-25% more.
Niall Litchfield
http://www.orawin.info/