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9 PS Series Asynchronous Replication Best Practices and Sizing Guide | BP1012
2.3 Local reserve, delegated space and replica reserve
Local reserve is a volume-level setting that defines how much space is allocated on the primary group to
support replication processing. Delegated space is a group -level setting that defines the total space
dedicated to receiving and storing inbound replica sets on the secondary group from a primary group
replication partner. Replica reserve is a volume-level setting that defines how much space is allocated per
volume from delegated space on the secondary group for storing all replicas of the volume (the replica set).
The locations and relationships between local reserve, delegated space and replica reserve are shown in
Figure 1.
Local reserve, replica reserve, and delegated space
A storage group can also have multiple replication partners. One typical example is where multiple locations
need to replicate to the same remote disaster recovery site. For example, in Figure 1, volumes within the
EAST and WEST groups are both replicating to the DR group. It is not necessary to have separate pools to
support each site. A single pool at the remote site can have partnerships with up to 16 other sites and receive
replicas from them. In Figure 1, two primary sites (EAST and WEST) are replicating into the same pool on the
secondary (DR) site. Of course the DR site in this example must be sized appropriately to support replica
storage requirements for both of the replication partnerships shown.