Data Domain : MTREE Replication

Mtree replication allows an mtree to be copied in its entirety between two Data Domain systems. The mtree replication will only copy blocks from the source to the target which do not exist on the target. Mtree replication can be used to provide a DR position, additional resiliency for a source Data Domain or to migrate from one unit to another. It should be remembered that any data which has been replicated via mtree replication will not be known within NetBackup. VTL mtree replication however can be thought of as similar to moving physical cartridges between libraries.

To view a list of mtrees available on the Data Domain

#mtree list

To set up the replication run the following command on both the source and target DD systems

# replication add source mtree://<SOURCE_DATA_DOMAIN_HOSTNAME>/data/col1/<MTREE_NAME> destination mtree:/<DESTINATION_DATA_DOMAIN_HOSTNAME>/data/col1/<MTREE_NAME>

The replication needs to be established between the configured hostnames of the data domain units, that is the hostname which is returned if the `hostname` command issued.

It may be that the replication data needs to traverse different interfaces however rather than the interface to which the data domain hostname, as configured in the command above, is bound to. The units may have interfaces connected to a dedicated backup network for example.

 

It is possible to amend the interface the replication data is sent over with the following command being run on the source data domain unit

# replication modify <replication_context> connection-host <target_data_domain_replication_hostname>

The reciprocal command needs to be run on the target data domain unit pointing at the correct interface on the source unit

# replication modify <replication_context> connection-host <source_data_domain_replication_hostname>

With the replication setup on each Data Domain it can then be initialised from the source unit

# replication initialize mtree://<SOURCE_DATA_DOMAIN_HOSTNAME>/data/col1/<MTREE_NAME>

There are several commands which can then be used to check the progress or performance of the replication, such as 

# replication show stats

# replication show detailed-history all