IBM XIV Storage System Copy Services and Migration

4.2 Mirroring schemesMirroring, whether synchronous or asynchronous, requires two or more XIV systems. Thesource and target of the asynchronous mirroring can reside on the same site and form a localmirroring or they can reside on different sites and enable a disaster recovery plan. Figure 4-3shows how peers can be spread across multiple storage systems and sites.Replication SchemeXIV System EXIV System BXIV System AMirrored CGMasterM irroredMirrored VolMasterMirrored CGMasterStoragePoolXIV System CMirrored CGSlaveXIV System DMirrored VolSlaveMirrored VolSlaveMirrored VolMasterMirrored CGSlaveStor agePoolStoragePoolFigure 4-3 Mirroring replication schemesUp to 16 targets can be referenced by a single system. A system can host replication sourcesand separate replication targets simultaneously.In a bi-directional configuration, an XIV system concurrently functions as the replicationsource (master) for one or more couplings, and as the replication target (slave) for othercouplings. If production applications are eventually running at both sides, the applications ateach site are independent from each other to ensure data consistency in case of a site failure.Figure 4-3 illustrates possible schemes for how mirroring can be configured.Chapter 4. Remote Mirroring 75