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8 PS Series Asynchronous Replication Best Practices and Sizing Guide | BP1012
Term
Description
Secondary group
A group containing the replica or copy of the source volume(s).
Destination group
Same as secondary group.
Delegated space
The amount of space on the secondary group that is delegated to a
replication partner, to be reserved for retaining replicas.
Replica reserve
The space allocated from delegated space in the secondary group to store
the volume replica set for a specific volume.
Local reserve
The amount of space reserved on the local or primary group for holding
temporary snapshots and failback snapshots of the source volume.
WAN emulator
A device used to simulate distance and impairments in a WAN.
1
PS4000, PS4010, PS4100, PS4110, PS-M4110, and PS4210 arrays may only have two members in a pool, or 28
members if using VMware Virtual Volumes (VVols).
2.2 Configuration limits and storage requirements
PS Series arrays allow for up to 256 volumes for replication per group (PS4000 to PS4210 series arrays are
limited to 32 volumes enabled for replication per group), but only 16 volumes per group can be simultaneously
replicating. A group may also have up to 16 replication partners. A volume can have only one replication
partner at a time.
Asynchronous replication requires reserved disk space on both the primary and secondary groups. The
amount of space required depends on several factors:
Volume size
The amount of data that changes (on the source volume) between each replication period
The number of replicas that need to be retained on the secondary site
If a failback snapshot is retained on the primary group
The default values that appear in Group Manager are sufficient to ensure that enough space is reserved for at
least one successful replication, even if the entire contents of a volume are altered between replicas. Initial
replication of a volume will cause the complete contents of the volume to be copied to the secondary group.
Subsequent replication events will copy only the changed data.