Administrator Guide

Data replication primer
12 Dell EMC SC Series: Synchronous Replication and Live Volume | CML1064
Figure 3 demonstrates the write I/O pattern sequence with semi-synchronous replication.
1. The application or server sends a write request to the source volume.
2. The write I/O is committed to the source volume.
3. The write acknowledgement is sent to the application or server.
The process is repeated for each write I/O requested by the application or server.
For each write I/O that completes that process, there is an independent and parallel process:
a. The write request is sent to the destination.
b. The write I/O is committed to the destination.
c. The write acknowledgement of the mirror copy is sent to the source array.
The commits at the source and destination volumes are not guaranteed to be in lockstep with each other.
Semi-synchronous replication write I/O sequence