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50 PS Series Asynchronous Replication Best Practices and Sizing Guide | BP1012
Another option, which in some cases may be quicker and easier, is to connect the secondary storage systems
in the local (primary) data center, establish the replication partnership, and do the initial full synchronization
over the full-speed, local iSCSI SAN network. After the initial replication is complete, shut down the secondary
storage and move it to the secondary or remote site. When the link is established, bring up the secondary
storage and only the delta changes (the differences since the previous replication) will be replicated.
As mentioned previously, the use of WAN accelerators or optimizers is yet another method that may help to
improve the efficiency of replicating large amounts of data over a WAN. These devices sit on either side of the
WAN link and perform functions such as data deduplication, caching, and other packet optimization.
7.8 SAN-based replication or host-based replication
The asynchronous replication feature ships with every PS Series array to help meet the needs of most
replication requirements. With host-based replication products, the host CPU will be responsible for reading
data off the SAN, and then moving it from the host to the destination replica site. There may be situations
requiring a host-based replication product instead of PS Series asynchronous replication. Here are some
examples:
 The specific RPO or RTO requirements of an application cannot be satisfied by the capabilities of PS
Series asynchronous replication alone.
 There is no network path available between the array controllers in the primary PS Series SAN group
and the secondary group, and using the Manual Transfer Utility will not meet RPO/RTO requirements.