We are the part of RDBMS world. As a student when we entered in the world of RDBMS we learned about the attributes of the entity.  I hope you have the idea what we are going to do in this post.  As the heading of the post explains. Today we are going to have look at ASM Disk Group Attributes. Before starting this we must know what is ASM Disk Group? This first line explains the technical definition of ASM Disk Group.

A disk group consists of multiple disks and is the fundamental object that Oracle ASM manages. Each disk group contains the metadata that is required for the management of space in the disk group. Disk group components include disks, files, and allocation units.


What is ASM Disk Group Attributes?

Disk group attributes are parameters that are bound to a disk group, rather than an Oracle ASM instance.

List of attributes are mention below:-

  • AU_SIZE:-   During the creation of the disk group in ASM we set this attribute. We can use this for specified the AU size.When we create a disk group, you can set the Oracle ASM allocation unit size with the AU_SIZE disk group attribute. Its values can be 1, 2, 4, 8, 16, 32, or 64 MB, depending on the specific disk group compatibility level. Larger AU sizes typically provide performance advantages for data warehouse applications that use large sequential reads.
    Every ASM disk is divided into allocation units (AU). An AU is the fundamental unit of allocation within a disk group. A file extent consists of one or more AU. An ASM file consists of one or more file extents.
  • DISK_REPAIR_TIME:-  It specifies the amount of time ASM will wait from when a disk goes offline until ASM drop it and rebalance the disk group. it allows for fast mirror resync feature, whereby ASM keeps track of pending on an online disk during an outage and the extent are automatically synced when the disk is brought back online.
  • COMPATIBLE.RDBMS:-   It explains the information about minimum software version required for the database instance to use files in this disk group.
  • COMPATIBLE.ASM:- It explains compatibility with minimum software version required for an ASM instance to mount this disk group.
  • COMPATIBLE.ADM:-  we can use this attribute to allows the creation of ASM volumes.
  • CONTENT.CHECK:-  it can enable or disable content checking when performing data copy operations like replacing a disk group. We can set TRUE or FALSE. What will be the effect if we set it true?  The logical content checking is enabled for all rebalance operations.
  • CONTENT.TYPE:-  With the help this attribute we can have full information about disk group(DATA, RECOVERY, or SYSTEM).
  • IDP.BOUNDARY:- For configuring Oracle Exadata Storage DBA can use this attribute.
  • IDP.TYPE:- It is also used for configuring Oracle Exadata storage.
  • SECTOR_SIZE:-  Used with CREATE  DISKGROUP to specify the disk sector size.
  • STORAGE_TYPE:- To know the type of the disks in the disk group.
  • ACCESS_CONTROL.ENABLED:- We can use this one for the creation of access control lists(ACL).
  • ACCESS_CONTROL.UMASK:- We can set the default permissions to be set for files created in the disk group.
  • CELL.SMART_SCAN_CAPABLE:- Enables smart scan predicate offload processing if all disk group disks are Exadata Grid Disks.
  • FAILGROUP_REPAIR_TIME:-  We can use the all specification a default repair time for the failure groups in the disk group.
  • THIN_PROVISIONED:-  DBA can enable/disable the functionality to discard unused storage space after a rebalance.

Thank you for giving your valuable time to read the above information.

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