Automatic Memory Management for ASM instance

[daljitsb]

Environment: Windows 2003, Oracle 10gR2, 2 node RAC with ASM and multiple databases

Is setting Automatic Memory Management (by setting parameter SGA_TARGET greater than zero) for ASM instance a good thing or not.

Do we have lot of overhead in using Automatic Memory Management, especially for instances that have a low amount of memory allocated. Does Oracle spend more time moving memory allocations back and forth between the pools than doing any real work.

We have about 20 databases running on RAC for that ASM instance.

[hrishy]

Hi

If i remember correctly the default setting for ASM instance is Automatic Memory Management unlesss you change it.

In my previous project i think it was Automatic for al 30+ ASM instances which i know of (unless i have a horrible memory and it has faded in last one month of my bench period :-D)

regards
Hrishy

[daljitsb]

If i remember correctly the default setting for ASM instance is Automatic Memory Management unlesss you change it.
Hrishy

Thanks Hrishy.

But then question is why am I getting this ORA-04031

Thats what I think is the case. But I don't even have the parameter 'SGA_TARGET' set when I look for its value.

I tried to alter sga_max_size to increase share_pool_size, I get error.

SQL> alter system set sga_max_size=140M;
alter system set sga_max_size=140M
*
ERROR at line 1:
ORA-02095: specified initialization parameter cannot be modified


SQL> alter system set shared_pool_size=80M scope=both;
alter system set shared_pool_size=80M scope=both
*
ERROR at line 1:

ORA-32001: write to SPFILE requested but no SPFILE specified at startup


I do have spfile created when I created ASM instance. I tried to change sga_max_size and shared_pool_size in paramater file, the ASM instance won't even start.

SQL> show sga

Total System Global Area 92274688 bytes
Fixed Size 1289076 bytes
Variable Size 65819788 bytes
ASM Cache 25165824 bytes
SQL> sho parameter shared

NAME TYPE VALUE
------------------------------------ ----------- ----------
hi_shared_memory_address integer 0
max_shared_servers integer
shared_memory_address integer 0
shared_pool_reserved_size big integer 2516582
shared_pool_size big integer 48M
shared_server_sessions integer
shared_servers integer 0
SQL> sho parameter target

NAME TYPE VALUE
------------------------------------ ----------- ----------
archive_lag_target integer 0
db_flashback_retention_target integer 1440
fast_start_io_target integer 0
fast_start_mttr_target integer 0
pga_aggregate_target big integer 18035507
sga_target big integer 0
SQL> sho parameter max

NAME TYPE VALUE
------------------------------------ ----------- ----------
java_max_sessionspace_size integer 0
license_max_sessions integer 0
license_max_users integer 0
log_archive_max_processes integer 2
logmnr_max_persistent_sessions integer 1
max_commit_propagation_delay integer 0
max_dispatchers integer
max_dump_file_size string UNLIMITED
max_enabled_roles integer 150
max_shared_servers integer
object_cache_max_size_percent integer 10

NAME TYPE VALUE
------------------------------------ ----------- ----------
parallel_max_servers integer 0
session_max_open_files integer 10
sga_max_size big integer 88M
SQL>

[pando]

you cannot increase sga_max_size and pretend it can allocate memory just like that

look oracle parameter references and see a detailed explanation

[PAVB]

Support Pando; just replace "pretend" with "expect" and all of it will make sense.

[abhaysk]

well but thats how Pando's lingo is.. :-)