A nice feature of VOL is by setting 2 environment variables HDF5_VOL_CONNECTOR and HDF5_PLUGIN_PATH, users can enable the VOL without changing their application source codes.
While developing a new VOL, we found that HDF5 library caches the values of these 2 variables for the remaining run of the application, no matter if users call unsetenv/setenv to change them before calling H5Fcreate or H5Fopen. This can affect applications that want to open a file using the native VOL and create a new file using another VOL, for example.
It will be great if these 2 VOL env variables can be rechecked at each file create and open time. It makes VOL more flexible. Is there an issue making this happened can be a problem?