Recently we have a read heavy batch job, running in DR env it tooks 1 hour, but in Prod same job tooks 5 hour.
Same hardware spec, same software version/patch, data is SAN replicated (except OS & Sybase binary which is not replicated).
Done few rounds of investigation, no where can find the different between Prod & DR.

Then at SAN storage we observed the difference, in Prod the average I/O size is 16K, and DR ave I/O size is 77K, during the batch job, and that is ~5 times different. However when running db backup we noticed the Prod server can push out more than 200K I/O size.

May I ask what are the Sybase setting affect the I/O size? How can I verify it?