Unanswered: Heavy Dynamic Prefetch.....How to control ?
Version details : DB2 V6.1; OS390 V2.8
One of my bufferpool is having Negative HIT ratio.
For that BP, there is only one large 32 Partitioned TSpace containing a heavily used table (mainly for online txn) of some million rows.
The reason I observed for negative hit ratio, is that, for the tableSpace allocated to the BP the usage of DYNAMIC PREFETCH (Async i/O) is far more than the no of GETPAGES requests.
I used the formula
HITRATIO = (GETPAGE-(SYNC_RIO + ASYNC_i/o) )/GETPAGE.
We tried with increasing the BPSIZE to three fold ...but didnot show any improvement in performance.
Could anybody help me out how to control the DYNAMIC PREFETCH ??