Recently we decided to consolidate the LUN’s presented to ASM on AIX box.
Prior to consolidation ASM was using 16 x 100G LUN’s. Post consolidation we would only have 2 LUN’s
1 x 1 TB
1 x 600 GB
SYSADMINS created new LUN’s and presented them to AIX server.
Now when I started creating the diskgroup, ASM was not allowing to create diskgroup and throwing following error
ERROR at line 1: ORA-15018: diskgroup cannot be created ORA-15099: disk '/dev/rhdiskXX' is larger than maximum size of 2097152 MBs
We knew disks are surely not exceeding this size. But when queried v$asm_disk
SQL>select path, total_mb, free_mb from v$asm_disk where header_status='CANDIDATE'; PATH TOTAL_MB FREE_MB -------------- ---------- ---------- /dev/rhdisk10 4293918720 0 /dev/rhdisk11 4293918720 0 /dev/rhdisk12 4293918720 0
It was showing CANDIDATE disks of size 4095TB. Well we even didn’t had that much store in SAN (so no question of sysadmin making any mistake)
Operating system was showing correct disk size
bootinfo -s hdisk10 1048576 bootinfo -s hdisk11 614400
After checking for known ASM & AIX bugs, found following
Bug 9495887: ASM RECOGNIZE 1.25 TB DISKS AS 4,095.25 TB DISKS ON AIX.
NOTE: As per this BUG, Versions confirmed as being affected is 126.96.36.199. But in my case it is also seen in 10.2.0.5
Workaround is to create diskgroup by specifying actual disk size
SQL> create diskgroup fradg external redundancy disk '/dev/rhdisk10' size 1000G, '/dev/rhdisk11' size 614400M;
Metalink Doc Ref –
NOTE [ID 9495887.8] – Bug 9495887 – AIX: ASM does not recognize correct diskgroup size for large disks
NOTE [ID 1095202.1] – ASM 11gR2 Incorrectly Recognize Disks (e.g. 1.25 TB) As 4,095.25 TB Disk On AIX.
NOTE [ID 1345562.1] – Master Note For Automatic Storage Management (ASM) For Operating System (OS) Administrators