Sun Microsystems 5310 NAS manual Volume Groups

■Standard volume - A logical structure created on a storage array for data storage. A standard volume is created using the Create Volume Wizard. If the premium feature is not enabled for snapshot volumes or Remote Volume Mirroring, then only standard volumes will be created. Standard volumes are also used in conjunction with creating snapshot volumes and remote mirror volumes.

■Snapshot volume - A point-in-time image of a standard volume. A snapshot volume is the logical equivalent of a complete physical copy, but you create it much more quickly and it requires less disk space. The volume from which you are basing the snapshot volume, called the base volume, must be a standard volume in your storage array.

■Snapshot repository volume - A special volume in the storage array created as a resource for a snapshot volume. A snapshot repository volume contains snapshot volume metadata and copy-on-write data for a particular snapshot volume.o Primary volume - A standard volume in a mirror relationship that accepts host I/O and stores application data. When the mirror relationship is first created, data from the primary volume is copied in its entirety to the associated secondary volume.

■Secondary volume - A standard volume in a mirror relationship that maintains a mirror (or copy) of the data from its associated primary volume. The secondary volume remains unavailable to host applications while mirroring is underway. In the event of a disaster or catastrophic failure of the primary site, the system administrator can promote the secondary volume to a primary role.

■Mirror repository volume - A special volume created as a resource for each controller in both the local and remote storage array. The controller stores mirroring information on the mirror repository volume, including information about remote writes that are not yet complete. The controller can use the mirrored information to recover from controller resets and accidental powering-down of storage arrays.

■Source volume - A standard volume that contains the data that will be copied to another volume, which is known as the target volume. A source volume can be either a standard volume, a snapshot volume, the base volume of a snapshot volume, or a primary volume of a mirrored pair.

■Target volume - A standard volume to which the data on the source volume is being copied. When a volume is selected as a target volume, any existing data on the volume will be completely overwritten and the volume will automatically become read-only after the copy operation has completed, to protect it from host write access. After the volume copy completes, you can use the Copy Manager to disable the Read-Only attribute for the target volume.

Volume Groups

A volume group is a set of drives that the controller logically groups together to provide one or more volumes to an application host. When creating a volume from unconfigured capacity, the volume group and the volume are created at the same time. When creating a volume from free capacity, an additional volume is created on an existing volume group (Figure 3-28).

Chapter 3 Storage Arrays 3-65