The system does work to push the invalid tracks over as quickly as possible however that is how it works.  Any I/O to a currently invalid track is treated as adaptive copy disk.  If you think about it this is how it has to work if you want the host to continue to run.  Edit to add:  If you were to dro this into synch mode very early it would take you a longer time to "catch up" to where you want to do into synch mode as you would be running synchronous I/O's (that have priority) while trying to still synch tracks that have to be read from disk.
So I've been re-reading my SRDF documentation. Specifically the bit where Adaptive copy will switch to SRDF/S to 'catch up' if the skew gets too high (which is configurable). Which of course, you can turn off. But I've been working on the notion that you should really use adaptive copy to 'catch up' your track skew, and switch to sync when it's 'about done'. I presume due to performance reasons.  So can anyone enlighten me - I couldn't spot it in the documentation - what happens when you enable SRDF/S with invalid tracks? Do all IOs get held until it's caught up? Or do new IOs get treated as 'synchronous' where old invalids are still playing catchup? I'd assume there was a performance impact to switching to sync with a lot to catch up, but is it significantly more than the 'normal' SRDF/S overhead?
SRDF/S with a lot of invalids