Dell SRDF Introduction

Write operations in synchronous mode

In synchronous mode, data must be successfully written to cache at the secondary site before a positive command completion status is returned to the application host that issued the write command.

The following diagram shows the steps in a synchronous write operation:

1. The application host sends a write command to the local array. The host emulations write data to the cache and create a write request.
2. SRDF emulations frame updated data in the cache according to the SRDF protocol, and transmit it across the SRDF links.
3. The SRDF emulations in the remote array receive data from the SRDF links, write it to the cache and return an acknowledgment to SRDF emulations in the local array.
4. The SRDF emulations in the local array forward the acknowledgment to host emulations which pass it on to the application host.