Why is DB2 (much) slower than Oracle?
Just performed a NW7.01 ECC6.04 Hetro migration Oracle 10G -> DB2 9.7.003. AIX 6.1 Power 5 -> AIX6.1 on Power 7, extra CPUs and extra memory. Everything is going well, except peformance is not as we had wished.
The new host has penty of horsepower (2times old) both CPU, Memory and IO (by way of an XIV disk array)
Can see plenty of batch jobs running in SAP (sm50) but can see infrastructure (Power 7, XIV disk array) running not even at 50% of CPU capacity and hovering around 10~20%of maximal IO demonstrated capacity. Indexing seems similar and query paths similar to Oracle. 20GB RAM allocated to DB2 instance (single central instance). DB is 1.5TB.
What is seems is that DB2 is not asking enough of the infrastructure, the old power5 system was driven harder by Oracle, ie it appears that Oracle was better at extracting more data in a single thread (disp+work) than DB2. This is particular apparent in sequential reads ( index range scans).
Any suggestions to force DB2 to make better use of the system resources available to it?