CV0-003 · Question #91
When the cache receives write data from the hosts, which of the following does the controller send back to the host?
The correct answer is D. Acknowledgement. In write-back caching, the controller sends an acknowledgement to the host once data is written to cache, confirming receipt before the data is flushed to persistent storage.
Question
When the cache receives write data from the hosts, which of the following does the controller send back to the host?
Options
- ARequest
- BHeader
- CFooter
- DAcknowledgement
How the community answered
(25 responses)- A4% (1)
- B8% (2)
- D88% (22)
Why each option
In write-back caching, the controller sends an acknowledgement to the host once data is written to cache, confirming receipt before the data is flushed to persistent storage.
A request is initiated by the host to begin an I/O operation and is not a response sent by the controller back to the host.
A header is a metadata component of a data packet or frame and is not a response type that a storage controller sends to confirm a write operation.
A footer is a trailing metadata element of a data structure and is not a mechanism used by storage controllers to confirm receipt of write data.
When a host sends write data to a storage controller using write-back cache, the controller writes the data to the fast cache memory and immediately returns an acknowledgement to the host signaling that the write is complete. This allows the host to continue processing without waiting for the slower operation of writing to disk. The actual destage of data from cache to disk occurs asynchronously afterward.
Concept tested: Write-back cache acknowledgement in storage controllers
Source: https://learn.microsoft.com/en-us/azure/well-architected/performance-efficiency/optimize-data-performance
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