06.08.2015 Views

IBM XIV Storage System Copy Services and Migration

IBM XIV Storage System: Copy Services and Migration - Common ...

IBM XIV Storage System: Copy Services and Migration - Common ...

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►Host read operations are performed from the Primary <strong>XIV</strong> (master role), whereas writing isperformed at the primary (master role) <strong>and</strong> replicated to the Secondary <strong>XIV</strong> systems.Refer to 5.5, “Synchronous mirror step-by-step scenario” on page 137, for more details.<strong>XIV</strong> asynchronous mirroring<strong>XIV</strong> asynchronous mirroring is designed to provide a consistent replica of data on a targetpeer through timely replication of data changes recorded on a source peer.<strong>XIV</strong> Asynchronous mirroring exploits the <strong>XIV</strong> snapshot function, which creates apoint-in-time (PiT) image. In <strong>XIV</strong> asynchronous mirroring, successive snapshots(point-in-time images) are made <strong>and</strong> used to create consistent data on the slave peers.The system sync job copies the data corresponding to the differences between twodesignated snapshots on the master (most_recent <strong>and</strong> last_replicated).For <strong>XIV</strong> asynchronous mirroring, acknowledgement of write complete is returned to theapplication as soon as the write data has been received at the local <strong>XIV</strong> system, as shownin Figure 4-2. Refer to 6.6, “Detailed asynchronous mirroring process” on page 173, fordetails.Application Server1231. Host Write to Master <strong>XIV</strong>(data placed in cache of 2Modules))2. Master acknowledges writecomplete to application3. Master replicates to Slave4. Slave acknowledges writecompleteLocal <strong>XIV</strong>(Master)4Remote <strong>XIV</strong>(Slave)Figure 4-2 <strong>XIV</strong> asynchronous mirroring74 <strong>IBM</strong> <strong>XIV</strong> <strong>Storage</strong> <strong>System</strong>: <strong>Copy</strong> <strong>Services</strong> <strong>and</strong> <strong>Migration</strong>

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