DPL: add option to force parentFile colocation

[ktf]

No description provided.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 883a847 at 2026-06-11 01:41:

## sw/BUILD/O2Physics-latest/log
CMake Error at /sw/slc9_x86-64/CMake/v4.1.4-2/share/cmake-4.1/Modules/CMakeTestCCompiler.cmake:67 (message):
    ninja: build stopped: subcommand failed.

Full log here.

[jgrosseo]

@costing I vaguely remember that there are SEs which are counted equivalent because they are close by. Would the check created by @ktf work for this case?

[costing]

I think the exact SE name is checked in the whereis output. Which is ok, the secondary files are supposed to be stored in the same locations as the original ones, not in nearby SEs.

Just that enabling this check for every file will double the load on the catalogue. We already return the list of PFNs at a ::Open() of the original and the secondary files. So if the check could be deferred to when the files are actually about to be used it would not put additional pressure on the databases. In this form it can be used for one time debugging / optimizing step, but it cannot be done regularly or by default.

[jgrosseo]

I agree. This should run as an extra special train and not be enabled for user trains.