Dell EqualLogic PS6210XS EqualLogic Group Manager Administrator s Guide PS Ser - Page 244

To disable snapshot space borrowing, clear the checkbox. NOTE: You can also control snapshot space borrowing under the Group Configuration Defaults tab. Settings specified here apply to newly created volumes only, not to existing volumes. About Replication The replication technology provided by PS Series firmware enables you to copy volume data from one group to another, protecting the data from a variety of failures, ranging from the destruction of a volume to a complete site disaster, with no effect on data availability or performance. Volume replication between different groups provides protection against data loss. If a volume is destroyed, you can fail over to the recovery group and recover data from a replica. Users can then resume access to the recovery volume. After the original volume becomes available, you can fail back to the original group. Traditional replication is different from synchronous replication (SyncRep). You cannot enable synchronous replication on a volume for which traditional replication is configured, and you cannot enable traditional replication on a volume for which synchronous replication is configured. NOTE: A group can have multiple replication partners. However, you can replicate a volume to only one replication partner at a time. Choose the replication configuration that is right for your environment. You can use PS Series replication functionality alone or with Auto-Snapshot Manager (for Linux and Windows), Dell Virtual Storage Manager for VMware (formerly ASM/VE), or Storage Replication Adapter for VMware Site Recovery Manager. See the related product documentation for details. The first step in implementing replication is to configure the replication partners. Replication partners can consist of two or more groups. In the simplest case, a primary group contains the volume you want to replicate and a secondary group stores the replicated data. Each partner plays a role in the replication of a volume, and you can monitor replication activity from either partner: • Primary group Location of the volume - The primary group administrator configures the secondary group as a replication partner and initiates the volume replication operation. Replication of the volume is considered outbound from the view of the primary group. • Secondary group Location of the volume's replica set - The secondary group administrator configures the primary group as a replication partner and delegates space for storing replicas from the primary group. Replication of a volume is considered inbound from the view of the secondary group (sometimes called the destination group). Mutual authentication using passwords provides security between partners. After you configure the two groups as replication partners, you can configure a volume or volume collection for replication, specifying the replication partner, the local group space for the replication operation, and the remote partner space for storing the replicas. The first time you replicate a volume, the primary group copies the entire contents of the volume to the secondary group. For subsequent replication operations, the primary group copies only the data that changed since the previous replication operation started. Eventually, the oldest replicas are deleted from the replica set to free space for new replicas. The amount of space that you allocate for storing replicas limits the number of replicas you can keep on the secondary group. NOTE: To ensure that a complete copy of volume data exists on the secondary group, the most recent, complete replica of a volume cannot be deleted. To access or recover volume data from replicas, you can: • Clone an individual replica to create a new volume on the secondary group. 244 About Backing Up and Protecting Your Data