Checking the Internal Consistency of Disk Group Metadata

You can check the internal consistency of disk group metadata using the ALTER DISKGROUP statement with the CHECK keyword. You can use this statement to check specific files in a disk group, specific disks or all disks in a disk group, or specific failure groups within a disk group. The disk group must be mounted to perform these checks.

By default, the CHECK DISK GROUP clause verifies all of the metadata directories. Oracle ASM displays summary errors and writes the details about the errors in an alert log. The CHECK keyword performs the following operations:

• Verifies the consistency of the disk

• Cross checks all of the file extent maps and allocation tables for consistency

• Checks that the alias metadata directory and file directory are linked correctly

• Verifies that the alias directory tree is linked correctly

• Checks that Oracle ASM metadata directories do not have unreachable allocated blocks

The REPAIR | NOREPAIR clause specifies whether Oracle ASM should attempt to repair errors that are found during the check. The default is NOREPAIR. Use the NOREPAIR clause to receive alerts about inconsistencies and to suppress Oracle ASM from resolving the errors automatically. The following example statement checks for consistency in the metadata for all disks in the data1 disk group:

ALTER DISKGROUP data1 CHECK ALL;