Just a reminder: this writeDomain call will do an MPI_Allreduce internally to detect where each participant should store its information in the global target buffer. If you do not want this and you already know the size/offset of each rank, use writeDomain(currentStep, globalSize, globalOffset, ...) interface instead.

It seems you are using [this](http://computationalradiationphysics.github.io/libSplash/classsplash_1_1_parallel_domain_collector.html#affdddb7cb251a4082aa349784e29b6a8) interface, right?
There is no stride, source buffer size and offset as described in your code comment.
Moreover, I am not sure if `splashGlobalOffsetFile` is what you want here. You use this as `domainOffset` which is the `Local offset of this subdomain.`. This has nothing to do with file offsets ...