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Configuring replication
22 Dell EMC SC Series: VMware Site Recovery Manager Best Practices | 2007-M-BP-V
Consistency states of frozen snapshot replications during plan execution
1. Once a snapshot is taken of the source volume, the delta changes begin transferring to the
destination immediately. The consistency state of the data within this snapshot is dependent on
whether or not the application had the awareness to quiesce the data before the snapshot was taken.
2. During a recovery plan test, a new snapshot is taken of the destination volume. This is performed per
the VMware SRM specification to capture the newest data that has arrived at the DR site. This means
that the consistency of the data is dependent on whether or not the previous snapshot was
completely transferred. For example, in Figure 6:
a. If the 4:00 p.m. snapshot taken at the primary site was application consistent, but only 75 percent
of the snapshot data had been transferred, the data is considered incomplete. It may be
necessary to perform a manual recovery in order to present the last complete snapshot to the
application (such as the 3:00 p.m. snapshot in Figure 6).
b. If the 4:00 p.m. primary site snapshot was application consistent and performed at the same time
as the SRM recovery snapshot, then 100 percent of that snapshot would transfer. As a result, a
new snapshot would include all of the 4:00 p.m. snapshot data, and the application consistency of
the data would be preserved.
3. Once the SRM recovery snapshot has been taken, a view volume is created from that snapshot.
4. The view volume is presented to the vSphere host (or hosts) at the DR site for the SRM to begin a
test execution of the recovery plan.