PRIMECLUSTER Global Disk Services Configuration and Administration Guide 4.1 (Solaris(TM) Operating System)

1.4 GDS Snapshot Features

GDS Snapshot is software that provides additional functions to GDS.

GDS secures data from disk failures using the mirroring function and realizes continuous service. However, the mirroring function is not capable of protecting data against accidental erasure by the user or data crash due to an application malfunction. Therefore, data back up is mandatory. In a traditional system, the service must be stopped to back up data. GDS Snapshot provides a function for realizing the backup operation that does not influence the service and allows for continuous service.

The causes of cessation of services are not only problems such as disk failure and data damage. In a traditional system, the service must be stopped even for intentional maintenance work such as volume expansion and work applying patches to software. The function provided by GDS Snapshot also reduces system stop time and service stop time when performing maintenance work.

Once GDS Snapshot is implemented, proxy volumes and shadow volumes become available. These volumes are virtual devices that are bound up with GDS logical volumes. The user can make use of the GDS Snapshot function by operating and accessing those proxy volumes and shadow volumes.

The following sections discuss the GDS Snapshot functions provided by proxy volumes and shadow volumes.