RecoverPoint Write Phase:

In the RecoverPoint replication process, the write splitter plays a crucial role in intercepting writes from the host and forwarding them to both the production storage and the RecoverPoint appliances (RPAs).

Write Splitter Functionality:

The write splitter intercepts write I/O requests from the host and splits the I/O to both the production LUN and the RPAs. This ensures that the data is written to both the primary storage and replicated copies.

Acknowledgement Process:

During the write phase, the write splitter must ensure that the data is successfully written to the production LUN before acknowledging the write request back to the host.

This is because the primary concern is ensuring data integrity and confirming that the data is safely stored in the production environment before any replication considerations.

Detailed Workflow:

Step 1: Host issues a write request.

Step 2: The write splitter intercepts the write request.

Step 3: The write splitter forwards the write to the production LUN and the RPAs.

Step 4: The production LUN processes the write and sends an acknowledgement back to the write splitter.

Step 5: Upon receiving the acknowledgement from the production LUN, the write splitter then sends an acknowledgement back to the host.

According to the Dell RecoverPoint for Virtual Machines 6.0.1 vSphere HTML5 Plugin Administrator's Guide:

'The write splitter sends an acknowledgement to the host after it receives an acknowledgement from the production LUN' (vrpa.pdf, p.17).

'Ensuring that the write is committed to the production LUN before sending an acknowledgement to the host guarantees data integrity and consistency' (vrpa.pdf, p.18).