What are candidate & provisioned disks in ASM

Disks that were discovered but that have not yet been assigned to a disk group have a header status of either CANDIDATE or PROVISIONED.

CANDIDATE

Disk is not part of a disk group and may be added to a disk group with the ALTER DISKGROUP statement

PROVISIONED

Disk is not part of a disk group and may be added to a disk group with the ALTER DISKGROUP statement. The PROVISIONED header status is different from the CANDIDATE header status.  Here PROVISIONED implies that an additional platform-specific action has been taken by an administrator to make the disk available for Automatic Storage Management.

For example, on Windows, the administrator used asmtool or asmtoolg to stamp the disk with a header, or on Linux, the administrator used ASMLib to prepare the disk for ASM.

 

Below are the various HEADER_STATUS in the v$ASM_DISK. I have taken below status from 11gR2.

· UNKNOWN – Automatic Storage Management disk header has not been read

· CANDIDATE – Disk is not part of a disk group and may be added to a disk group with the ALTER DISKGROUP statement

· INCOMPATIBLE – Version number in the disk header is not compatible with the Automatic Storage Management software version.

· PROVISIONED – Disk is not part of a disk group and may be added to a disk group with the ALTER DISKGROUP statement. The PROVISIONED header status is different from the CANDIDATE header status in that PROVISIONED implies that an additional platform-specific action has been taken by an administrator to make the disk available for Automatic Storage Management.

· MEMBER – Disk is a member of an existing disk group. No attempt should be made to add the disk to a different disk group. The ALTER DISKGROUP statement will reject such an addition unless overridden with the FORCE option

· FORMER – Disk was once part of a disk group but has been dropped cleanly from the group. It may be added to a new disk group with the ALTER DISKGROUP statement.

· CONFLICT – Automatic Storage Management disk was not mounted due to a conflict

· FOREIGN – Disk contains data created by an Oracle product other than ASM. This includes datafiles, logfiles, and OCR disks.

When adding a disk, the FORCE option must be used if Oracle ASM recognizes that the disk was managed by Oracle. Such a disk appears

in the V$ASM_DISK view with a status of FOREIGN.