You can use VSTs to determine how many after-image blocks have been written. The VST table used for this purpose is _ActAILog. The fields with the relevantinformation are _AiLog-TotWrites and _AiLog-BytesWritn. The _AiLog-TotWrites field's value is an integer representing the number of after-image blocks written to after-image files.
Refer to the after-image block size to see how much data is involved. Take samples at the start of the time period and at the end of the time period. The difference between these fields results in the count of after-image blocks that have been written.
Using this method to determine after-image volume is preferable to other methods, as it is more flexible, easier to maintain, and less intrusive on database performance.
