First introduced in Oracle Database 11g, disk group attributes govern various aspects of how a disk group functions.
AU_SIZE specifies the allocation unit size, which is the fundamental unit of space within a disk group. It is also the stripe size for coarse-grained striping. This attribute can be set only during disk group creation.
DISK_REPAIR_TIME specifies the amount of time ASM will wait from when a disk goes offline until ASM drops it and rebalances the disk group. This attribute enables the fast mirror resync feature, whereby ASM keeps track of pending changes on an offline disk during an outage and the extents are automatically resynced when the disk is brought back online.
There are three compatibility attributes. COMPATIBLE.RDBMS specifies the minimum software version required for a database instance to use files in this disk group, whereas COMPATIBLE.ASM specifies the minimum software version required for an ASM instance to mount this disk group. The compatibility attributes are discussed in greater detail later in this lesson.
The value for the disk group COMPATIBLE.ADVM attribute determines whether the disk group can contain Oracle ASM volumes. The COMPATIBLE.ASM must be set to 11.2 first, and the ASM Dynamic Volume Manager (ADVM) drivers must be loaded.
ACCESS_CONTROL.ENABLED and ACCESS_CONTROL.UMASK are discussed in more detail in the lesson tilted “Administering ASM Files, Directories, and Templates.” Both attributes can be set after the disk group is created.
SECTOR_SIZE is used to support 4KB sector disk drives.
From Oracle Database 11g version 11.1.0.7, there is a new attribute, CELL.SMART_SCAN_CAPABLE, that enables smart scan predicate offload processing if all disks in the disk group are Exadata Grid Disks.
$ asmcmd lsattr -lm -G DATA
AU_SIZE specifies the allocation unit size, which is the fundamental unit of space within a disk group. It is also the stripe size for coarse-grained striping. This attribute can be set only during disk group creation.
DISK_REPAIR_TIME specifies the amount of time ASM will wait from when a disk goes offline until ASM drops it and rebalances the disk group. This attribute enables the fast mirror resync feature, whereby ASM keeps track of pending changes on an offline disk during an outage and the extents are automatically resynced when the disk is brought back online.
There are three compatibility attributes. COMPATIBLE.RDBMS specifies the minimum software version required for a database instance to use files in this disk group, whereas COMPATIBLE.ASM specifies the minimum software version required for an ASM instance to mount this disk group. The compatibility attributes are discussed in greater detail later in this lesson.
The value for the disk group COMPATIBLE.ADVM attribute determines whether the disk group can contain Oracle ASM volumes. The COMPATIBLE.ASM must be set to 11.2 first, and the ASM Dynamic Volume Manager (ADVM) drivers must be loaded.
ACCESS_CONTROL.ENABLED and ACCESS_CONTROL.UMASK are discussed in more detail in the lesson tilted “Administering ASM Files, Directories, and Templates.” Both attributes can be set after the disk group is created.
SECTOR_SIZE is used to support 4KB sector disk drives.
From Oracle Database 11g version 11.1.0.7, there is a new attribute, CELL.SMART_SCAN_CAPABLE, that enables smart scan predicate offload processing if all disks in the disk group are Exadata Grid Disks.
$ asmcmd lsattr -lm -G DATA
Group_Name Name Value RO Sys
DATA access_control.enabled FALSE N Y
DATA access_control.umask 066 N Y
DATA au_size 1048576 Y Y
DATA cell.smart_scan_capable FALSE N N
DATA compatible.asm 11.2.0.0.0 N Y
DATA compatible.rdbms 10.1.0.0.0 N Y
DATA disk_repair_time 3.6h N Y
DATA sector_size 512 Y Y
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