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Global-Active Devices for HDS Storage Arrays

The global-active device (GAD) is a virtual volume that spans across physical storage systems that are separated by up to metro distances. The GAD provides non-disruptive, highly available data, and continuous I/O, even when one of the members of the GAD fails.

With Commvault software, you can configure virtual storage machine (VSM) array details in Array Management and enable snapshot backups of GAD pairs. Then, you can use IntelliSnap backups to create snapshots of GAD pairs on Hitachi Virtual Storage Platform G1000 (VSP G1000) storage systems. The GAD configurations are supported through existing IntelliSnap features such as Array Controllers and the Remote Snap MediaAgent.

With the Commvault software, you can configure virtual storage machine (VSM) arrays and GAD pairs that you can create to maintain a synchronous, remote copy of a data volume on the primary VSP G1000 storage system.

The HDS VSP using Targetless CCI Engine does not support GAD.

Technical Details of the Global-Active Devices for HDS Storage Arrays

VSM arrays function as physical storage arrays. You create the resources that are provisioned to the VSM in a base storage array, but the VSM array functions independently.

GADs consist of array pairs, one of which is a VSM array, to maintain two copies of the data and to provide uninterrupted I/O, failback mechanisms, and failover mechanisms. The array pair is called a GAD pair.

The GAD pair keeps a local copy and a remote and synchronous copy of the data. There are two possible combinations for GAD pairs:

  • Physical + VSM: One end of the GAD pair is a VSM array, and the other end is a physical array.
  • VSM + VSM: Both ends of the GAD pair are VSM arrays.

In the Commvault software, the VSM arrays use the thin image (TI) engine or the shadow image (SI) engine of the HDS virtual storage platform (VSP) to back up data. You can then move the backed-up data to disks or to tapes, and you can restore it.

 IntelliSnap supports the following ways of protecting GAD pairs:

  • In MetroCluster environments by creating snapshots at both ends of a GAD pair
  • In a single server where data resides on a GAD pair along with a Microsoft Multipath I/O (MPIO) solution or a Hitachi Dynamic Link Manager (HDLM) solution
  • In a clustered server, where data resides on a GAD pair, with or without a cross-path configuration

Last modified: 3/1/2019 9:53:46 PM