SRDF/S uses FIFO technique - Realtime

SRDF/A uses cache based deltaset architecture - Data gets transferred once in 15 seconds [Default Cycle Switch Time]

I also understand SRDF/ACP is not a DR/restartable solution like SRDF/A & SRDF/S, but I would like to understand the transfer'period' time for SRDF/ACP mode.

Information from ECN:

With ACP each and every write made from host to array is copied to the target array - so if the host writes data to the same track (i.e. overwrites data) it will copy both writes across the link. Does it mean IO by IO? Without any delay?

From Document:

In adaptive copy write pending mode, data stays in cache until the SRDF emulation moves it across the SRDF links. --> Until? Not IO by IO?

In adaptive copy disk mode, the drive emulation writes data from cache to disk and schedules a request for the SRDF emulation to move data across the SRDF links. When data is scheduled to be sent across the SRDF links, the drive emulation, if needed, writes data back to cache. --> Scheduled? Any defined time period?

The SRDF adaptive copy modes allow the R1 and R2 devices to be more than one write I/O and up to the maximum skew value out of synchronization. By default, the maximum skew value is set to 65535 tracks. Once the maximum skew value is reached, the SRDF emulations must start the synchronization process to transfer updates across the SRDF links from the R1 to the R2 devices. --> Once the maximum skew value is reached? Does it mean transfer will not be kicked off until maximum skew value is reached i.e., 65535 tracks [4GB?]?