Some support was added to random_directio for testing it with tiered storage. That testing used the original session->flush_tier API which has been removed. In WT-9955 that API usage was modified to use the current checkpoint API usage, modeled after the usage in schema_abort.

However that code change was never fully tested for random_directio. This ticket should focus on testing and making tiered storage testing work for random_directio.

Background: random_directio tests that we are writing the correct things to disk. I works by running a workload a while, then suspending the workload. The test uses direct IO to make a copy of the workload database files – i.e., it bypasses the OS page cache to copy what has actually made it to disk – then makes sure it can restart from it. For tiered storage, we want to do the same thing with local files. There is no need to copy the data in object storage.