The MROLRM system initialization parameter can have a significant effect on the performance of a workload in an MRO function shipping environment.
Setting MROLRM=NO causes the mirror to be attached and detached for each function-shipped request until the first request for a recoverable resource or a file control start browse is received. After such a request is received, the mirror remains attached to the session until the calling transaction reaches syncpoint.
Setting MROLRM=YES in a region receiving function shipping requests causes a mirror transaction to remain attached to the MRO session from first request until the calling transaction reaches syncpoint. This option causes system-dependent effects, as follows:
In general, setting MROLRM=YES is recommended.
Setting MROFSE=YES in the front-end region prevents the
mirror task in the back-end region from being terminated after syncpoint.
The mirror task in the back-end region will only be terminated when the front-end
task terminates.
Use of MROFSE=YES in the front-end region is not recommended
when long-running tasks may be used to function-ship requests. This is because
a SEND session will be unavailable for allocation to other tasks when unused.
It might also prevent the connection from being released when contact has
been lost with the back-end region, until the task terminates or issues a
function-ship request.