ASM Diskgroup Creation Issue

Question

I have 6, two node RAC databases running in the two physical servers.

While I try to create new diskgroup, I get the following error:

ORA-15018: diskgroup cannot be created 
ORA-04031: unable to allocate 2110040 bytes of shared memory ("large 
pool","unknown object","large pool","kfr redo buffer") 

I gather that there isn't enough shared pool resources for the ASM instance to create a new diskgroup. I'm not in a situation to restart ASM instance to increase the shared pool.

My question is if I decide to drop some unused diskgroups will I get to create new diskgroups? Or is it mandatory to increase the shared pool?

Answer 1

15018, 00000, "diskgroup cannot be created"

Cause: The specified diskgroup could not be created.
Action: Check for additional errors reported.

04031, 00000, "unable to allocate %s bytes of shared memory (\"%s\",\"%s\",\"%s\",\"%s\")"

Cause: More shared memory is needed than was allocated in the shared pool or Streams pool. Action: If the shared pool is out of memory, either use the DBMS_SHARED_POOL package to pin large packages, reduce your use of shared memory, or increase the amount of available shared memory by increasing the value of the initialization parameters SHARED_POOL_RESERVED_SIZE and SHARED_POOL_SIZE. If the large pool is out of memory, increase the initialization parameter LARGE_POOL_SIZE.
If the error is issued from an Oracle Streams or XStream process, increase the initialization parameter STREAMS_POOL_SIZE or increase the capture or apply parameter MAX_SGA_SIZE.

There could be two reasons to get this error:

If you are using 11.2.0.2 then there could be a bug(Bug 11684854 : ASM ORA-4031 IN LARGE POOL FROM CREATE DISKGROUP) cosider to upgrade to 11.2.0.3 or higher.

You are running out of Large Pool memory. You have to add memory on large pool size. Also you could consider to use Automatic Memory Management as per this MOS DOC(Doc ID 1107613.1).

Answer 2

Sure you can try, here is my quick test (on 11.2.0.4):

SQL> select pool, bytes from v$sgastat where name = 'free memory';

POOL              BYTES
------------ ----------
shared pool   503941528
large pool      6422528

SQL> drop diskgroup o6cb_fra including contents;

Diskgroup dropped.

SQL> select pool, bytes from v$sgastat where name = 'free memory';

POOL              BYTES
------------ ----------
shared pool   504016600
large pool      8531968

Notice that the increase in free memory (2109440) is almost the same amount that was written in your error message (2110040).

But since you are on 11.2.0.3, if you use default memory settings for ASM, I highly recommend setting the memory parameters manually. The default memory allocation for < 11.2.0.4 versions is too low, it is a recurring issue. 11.2.0.4 allocates at least 1 GB memory, but 11.2.0.3 still uses around 300 MB (which causes problems like the above).

The recommended setting is:

alter system set memory_max_target=4096m scope=spfile sid='*';
alter system set memory_target=1536m scope=spfile sid='*';

From: ASM & Shared Pool (ORA-4031) (Doc ID 437924.1)