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In a simple write-through mode, each put and remove operation involves a corresponding request to the persistent store; therefore, the overall duration of the update operation might be relatively long. Additionally, an intensive cache update rate can cause an extremely high storage load. For such cases, you can enable the write-behind mode, in which update operations are performed asynchronously. The key concept of this approach is to accumulate updates and asynchronously flush them to the underlying database as a bulk operation.

Write Behind is s key capability as it ensures that write operations are lightening fast, at the same time it is absolutely required to know that write behind is working properly because any glitch in it's operation can cause loss of data. That's the reason it is important to always monitor this process so that if there is an issue in it's operation, it can be fixed before the cache is flushed.

This test monitors the write behind operations and gather key metrics like frequency, overflow, errors etc., which can provide valuable insights into the process efficiency and health.

Measurement	Description	Measurement Unit	Interpretation
wrtBehBufferSize	Indicates the total count of cache entries which are not yet saved down to disk database.	Number	Indicates the total count of cache entries which are not yet saved down to disk database.
wrtBehCriticalOverflow	Indicates the total number of cache overflow events recorded since the write-behind cache has been turned on.	Number	If there are too many cache overflow events, means the cache size is less than needed for application performance.
wrtBehErrorRetry	Indicates the total number of cache entries which are currently in retry mode.	Number	If there are too many errors resulting in retries it could be a problem with database which needs to be investigated.
wrtBehFlushFrequency	Indicates the time period after which write behind operations is invoked.	Seconds	Frequency and batch size should be set to an optimal value, it should not too high that too much data is being accumulated and no too low that there is no value.
wrtBehFlushSize	Indicates the size of internal buffer that triggers write behind operation even before it is due.	MB
wrtBehFlushThread	Indicates the number of threads employed in write behind operation.	Number	There should be optimal number of threads performing the operation, in case the operation is taking more time than required, you might have to think about adding more threads.
wrtBehStoreBatchSize	Indicates the maximum size of batch for write behind operation.	MB	Batch size should be set to an optimal value.
wrtBehTotalCritOverflow	Indicates the total number of cache overflow events recorded since the write-behind cache has been turned on.	Number	If there are too many cache overflow events, means the cache size is less than needed for application performance.