Administrator Guide

Working in the Replications topic
Topics:
• About replicating virtual volumes in the Replications topic
• Viewing replications
• Querying a peer connection
• Creating a peer connection
• Modifying a peer connection
• Deleting a peer connection
• Creating a replication set from the Replications topic
• Modifying a replication set
• Deleting a replication set
• Initiating or scheduling a replication from the Replications topic
• Stopping a replication
• Suspending a replication
• Resuming a replication
• Manage replication schedules from the Replications topic
About replicating virtual volumes in the
Replications topic
Replication for virtual storage provides a remote copy of a volume, volume group, or snapshot—thereafter known as volume—on a
remote system by periodically updating the remote copy to contain a point-in-time consistent image of a source volume. After an initial
image has been replicated, subsequent replications only send changed data to the remote system. All replications, including the initial one,
only replicate data that has been written as opposed to using all pages of data from the source. This feature can be used for disaster
recovery, to preserve data, and to back data up to off-site locations. It can also be used to distribute data.
Replication prerequisites
To replicate a volume, you must first create a peer connection and replication set. A peer connection establishes bi-directional
communication between a local and remote system, both of which must have FC or iSCSI ports and a virtual pool. The system establishes
a peer connection by connecting a host port on the local system with a user-specified host port on the remote system, then exchanging
information and setting up a long term communication path in-band. Because the communication path establishes a peer connection
between the two systems, replications can occur in either direction.
To verify that a host port address is available before creating a peer connection, use the query peer-connection CLI command. This
command provides information about the remote system, such as inter-connectivity between the two systems, licensing, and pool
configuration. For more information on this command, see the Dell EMC PowerVault ME4 Series Storage System CLI Guide. For more
information on peer connections, see Creating a peer connection, Deleting a peer connection, and Modifying a peer connection.
After you create a peer connection, you can create a replication set. A replication set specifies a volume, snapshot, or multiple volumes in a
volume group (hereafter known as volume) on one system of the peer connection, known as the primary system in the context of
replication, to replicate across the peer connection. When you create a replication set, a corresponding volume is automatically created on
the other system of the peer connection, known as the secondary system, along with the infrastructure needed for replication. The
infrastructure consists of internal snapshots used for replication operations:
• A replication set for a volume consumes two internal snapshots each for the primary volume and the secondary volume if the queue
policy is set to Discard, or three each if the queue policy is set to Queue Latest.
• A replication set for a volume group consumes two internal volume groups if the queue policy is set to Discard, or three if the queue
policy is set to Queue Latest. Each internal volume group contains a number of volumes equal to the number of volumes in the
base volume group.
Internal snapshots and internal volume groups count against system limits, but do not display.
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