Clariion Cache: Read and Write Caching
Clariion Read Caching
The Diagram on the left explains Read Caching (Only One SP involved in this process)
Step A: The host is requesting data from the active path to the Clariion.
Step B: If the data is in Cache, the data is sent over to the host.
Step Aa: This step comes into picture if the requested data is not in cache and is now requested from the Disk.
Step Ab: The Disk reads the data in the cache and Step B is performed completing the request.
Clariion Write Caching
The Diagram on the right explains Write Caching (Both the SP’s are involved in this process)
Step A: The host writes data to the disk (lun) through the active path between Host and Clariion. The data is written in cache.
Step B: The Data from above is in Cache (example SPA) is now copied over to the Cache of SPB using the Clariion Messaging Interface (CMI)
Step C: At this point an acknowledgement is sent to the host that the Write is now complete.
Step D: Using the Cache flushing techniques the data is written to the Clariion Disk (lun)