Configuring ASM: Disk Groups Page

Use the Configure ASM: Disk Groups page to:

  • Create a new disk group

  • Add disks to an existing disk group

  • Edit the disk compatibility attributes for a disk group

  • Manage the templates of any disk group

  • Mount, dismount, mount all, dismount all, and drop diskgroups

Configure ASM: Disk Groups Page Sections

Configure ASM: Disk Groups page is arranged into the following sections. To access help for a particular section of the page, click the Help button for that section, or click one of the following links.

  • Creating a Disk Group

  • Edit Attributes for Disk Group Page

  • Manage Templates Page

Disk groups are mounted automatically at ASM instance startup. This makes them available to all database instances running on the same node as ASM. The disk groups are dismounted at ASM instance shutdown. ASM also automatically mounts a disk group when you initially create it, and dismounts a disk group if you drop it.

Element Description
Disk Group Name Name of the disk group
Size (GB) Size of the disk group in GB.
Free (GB) Reflects the free space in GB after taking mirroring into account.
Redundancy Values can be any of the following:

  • EXTERNAL. Requires a minimum of one disk device. The effective disk space in an external redundancy disk group is the sum of the disk space in all of its devices. If you select this option, ASM does not mirror the contents of the disk group.

  • NORMAL. By default ASM uses two-way mirroring for datafiles and three-way mirroring for control files, to increase performance and reliability. Alternatively, you can use two-way mirroring or no mirroring. A normal redundancy disk group requires a minimum of two failure groups (or two disk devices) if you use two-way mirroring. The effective disk space in a normal redundancy disk group is half the sum of the disk space in all of its devices. For most installations, Oracle recommends that you use normal redundancy disk groups.

  • HIGH. The contents of the disk group are three-way mirrored by default. To create a disk group with high redundancy, you must specify at least 3 failure groups (a minimum of 3 devices). Although high-redundancy disk groups provide a high level of data protection, you must consider the higher cost of additional storage devices before deciding to use this redundancy level.
State Values can be any of the following:

  • MOUNTED. Disk groups are mounted automatically at ASM instance startup. This makes them available to all database instances running on the same node as ASM. To unmount a disk group whose state is originally set to MOUNT, right click to select the option DISMOUNT.

  • DISMOUNTED. The disk groups are dismounted at ASM instance shutdown. ASM also automatically mounts a disk group when you initially create it, and dismounts a disk group if you drop it. To mount disk groups whose state is originally set to UNMOUNT, by right click the selected diskgroup and select MOUNT.

Click Mount All to mount all the disk groups, and click Unmount All to dismount all the disk groups together.

Right-click a disk group to add a disk group, edit attributes for the disk group, manage templates, drop or dismount the disk group.

Related Links

Creating a Disk Group

Edit Attributes for Disk Group Page

Manage Disk Group Templates Page