EMS LOG About SNAPMIRROR SYNCHORONOUS EXCEPTION Splitter critical thresh

"HA Group Notification from node1 (SNAPMIRROR SYNCHORONOUS EXCEPTION: Splitter critical threshold breached [OWM]) NOTICE" were received,  but snapmirror still insycn. 

I was find in same question in communtiy,  it was say that "It just recorded the event that one of the snapmirror synchronous resource pool (OWM) has reached a high threshold, due to which a recycling was activated to reclaim the unused ones. This is indicative of a workload operating on many small files. That's what triggered this event."

But I still have few point didn't  understand. My question as below:

1. The root cause is still unknown, why will trgger out?
2. Why OWM hit the threshold ? 
3. Why there was so much workload operating on many small files ?

Thank you.