FPEM859 You will not receive information about asynchronous I/Os

Explanation
 Qualifying the plan or the authorization ID in
the Db2 START TRACE command
for performance trace class 4 restricts the data that Db2 produces to your task TCB and omits all asynchronous
tasks including Sequential Prefetch.

User response
 To ensure that all Sequential Prefetch related
I/O is traced by Db2 and subsequently
reported by Db2 PE, do not qualify
by plan or by authorization ID.