Dell MD3600f, MD3620F manual Asynchronous Replication Mode

Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide

Asynchronous Replication

Asynchronous replication removes the restriction that the remote write has to complete along with the local primary write. The MD36X0f will separately queue each remote write to allow the local primary write completion to signal Host I/O completion (thus no waiting for the remote write to complete). Instead, the MD36X0f will manage the queue of remote writes and ensure they all complete eventually.

Figure 3: Asynchronous Replication Mode

1	Host sends Write Request
2.1	Primary(local) controller at the local site takes in the request and stores the request in
	the Replication Repository
2.2	Primary (local) controller writes the data into the primary virtual disk
3	Primary controller sends the completion status to Host
4	Primary controller then sends the write request to the Secondary controller at the
	Remote Site
5	The secondary controller then processes the write request
6	Once the write request is processed, Secondary Controller sends acknowledgement
	to Primary Controller
7	Primary controller removes the entry from the Remote Repository

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