Note 387206.1 ORA-15041: ASM diskgroup with unlike disks sizes

Applies to:

Oracle Server - Enterprise Edition - Version: 10.1.0.2 to 10.2.0.1 - Release: 10.1 to 10.2
Information in this document applies to any platform.

Symptoms

When trying to add datafile to an existing DiskGroups will fail as below even if there sufficient available free space. 
in the diskgroup. 
. 
SQL> alter tablespace testtbs add datafile '+TESTDG1' size 100M; 
alter tablespace testtbs add datafile '+TESTDG1' size 100M 
* 
ERROR at line 1: 
ORA-1119: error in creating database file '+TESTDG1' 
ORA-17502: ksfdcre:4 Failed to create file +TESTDG1 
ORA-15041: diskgroup space exhausted

Cause

The problem occurs when there is a lot of free space in the disk group, but a file cannot be allocated because the free space is not evenly distributed.

Solution

1. Rebalance the diskgroup manually 

OR 

2. Use similarly size disks. 

Testcase 
----------- 
1. create tablespace testtbs at DB instance (1) 
. 
SQL> create tablespace testtbs datafile '+TESTDG1' size 500M; <== 
. 
2. check views at ASM instance 
. 
SQL> select path, free_mb,total_mb,state from v$asm_disk; 

PATH                                        FREE_MB   TOTAL_MB  STATE 
--------------------------------- -----------   --------------  -------- 
/dev/vgs11/rrac1012s_disk01                  24                  300  NORMAL 
/dev/vgs11/rrac1012s_disk02                222                  500  NORMAL 

SQL> select name,free_mb,total_mb,state from v$asm_diskgroup; 

NAME      FREE_MB  TOTAL_MB  STATE 
----------- -----------   -------------  ----------- 
TESTDG1            246                800  MOUNTED 

3. add datafile at DB instance (2) ==> ORA-15041 
. 
SQL> alter tablespace testtbs add datafile '+TESTDG1' size 100M; 
alter tablespace testtbs add datafile '+TESTDG1' size 100M 
* 
ERROR at line 1: 
ORA-1119: error in creating database file '+TESTDG1' 
ORA-17502: ksfdcre:4 Failed to create file +TESTDG1 
ORA-15041: diskgroup space exhausted 
. 
4. execute rebalance at ASM instance 
. 
SQL> alter diskgroup testdg1 rebalance; 
. 
5. check views at ASM instance 
. 
SQL> select path, free_mb,total_mb,state from v$asm_disk; 

PATH                                        FREE_MB TOTAL_MB STATE
--------------------------------- ----------- -------------- --------
/dev/vgs11/rrac1012s_disk01                  85                300 NORMAL 
/dev/vgs11/rrac1012s_disk02                161                500 NORMAL 

SQL> select name,free_mb,total_mb,state from v$asm_diskgroup; 

NAME      FREE_MB TOTAL_MB STATE 
----------- ------------ ------------- ----------- 
TESTDG1            246                800 MOUNTED 

6. add datafile at DB instance ==> succeed 
. 
SQL> alter tablespace testtbs add datafile '+TESTDG1' size 100M; 
. 
7. check views at ASM instance 
. 
SQL> select path, free_mb,total_mb,state from v$asm_disk; 

PATH                                    FREE_MB TOTAL_MB STATE 
------------------------------ ----------- -------------- -------- 
/dev/vgs11/rrac1012s_disk01             35                300 NORMAL 
/dev/vgs11/rrac1012s_disk02           110                500 NORMAL 

SQL> select name,free_mb,total_mb,state from v$asm_diskgroup; 

NAME      FREE_MB TOTAL_MB STATE 
----------- -----------  ------------- ----------- 
TESTDG1            145               800 MOUNTED 
. 

Diskgroup is 800MB and when we try to create tablespace of 500M and trying to add a datafile of 100M will fail even though there is a free space of 246MB in the diskgroup but the same succeeds after rebalance.