2.2.5 Volume Management

Sun Cluster uses volume management software to group disks into disk groups that can then be administered as one unit. Sun Cluster supports Solstice DiskSuite, Sun StorEdge Volume Manager (SSVM), and Cluster Volume Manager (CVM). You can use only one volume manager within a single cluster configuration.

You must install the volume management software after you install the Solaris operating environment. You can install the volume management software either before or after you install Sun Cluster software. Refer to your volume manager software documentation and to Chapter 3, Installing and Configuring Sun Cluster Software, for instructions on installing the volume management software.

Use these guidelines when configuring your disks:

• Mirroring of root disks is recommended, but not required.

• All multihosted disks must be mirrored across arrays. An exception to this is the Sun StorEdge A3000, which is configured to mirror or provide hardware RAID5.

• Use of hot spares is highly recommended, but not required.

See "Volume Manager Slices" for disk layout recommendations related to volume management, and consult your volume manager documentation for any additional restrictions.

2.2.5.1 Solstice DiskSuite Considerations

Consider these points when planning Solstice DiskSuite configurations:

• Always use trans metadevices for file systems within disksets.

• If you run with only two disk expansion units, you will need to use Solstice DiskSuite mediators.

• When using Solstice DiskSuite mediators with any disksets in your configuration, only two cluster nodes can act as mediator hosts. Those two nodes must be used for all disksets requiring mediators, regardless of which nodes master those disksets. Therefore, in Sun Cluster configurations with more than two nodes, it is possible for a diskset's mediator host to be one that is not actually a potential master of that diskset.

2.2.5.2 Sun StorEdge Volume Manager and Cluster Volume Manager Considerations

Consider these points when planning SSVM and CVM configurations:

• You must create a default disk group (rootdg) on each cluster node. The rootdg group consists of either one slice (a "simple" disk) or a whole disk. It can be encapsulated.

• If the rootdg consists of a simple disk, a one slice table entry and at least two cylinders on the root disk must be left free.

• If the rootdg is encapsulated, then two disk slice table entries must be left free. In addition, only the root (/), /usr, /var, and swap file systems should be present on the encapsulated root disk.

• Encapsulation makes it more difficult to upgrade the volume manager software; if you anticipate frequent upgrades, encapsulating the rootdg is not recommended. However, if you want to mirror the root disk, you must encapsulate the rootdg.

Insufficient disk space and slices prevent encapsulation of the boot disk later and increase installation time because the operating environment might have to be reinstalled.

You will need licenses for Sun StorEdge Volume Manager if you use it with any storage devices other than SPARCstorage Arrays or Sun StorEdge A5000s. SPARCstorage Arrays and Sun StorEdge A5000s include bundled licenses for use with SSVM. Contact the Sun License Center for any necessary SSVM licenses; see http://www.sun.com/licensing/ for more information.

You do not need licenses to run Solstice DiskSuite or Cluster Volume Manager with Sun Cluster.