Would a RAM disk fit the bill? Just read all the contents from the copy in non-volatile storage at boot. Cross-platform then by virtue of using what-ever RAM-ba

Would a RAM disk fit the bill? Just read all the contents from the copy in non-volatile storage at boot. Cross-platform then by virtue of using what-ever RAM-based filesystem or block-device options are commonly available on the target OS. For “as fast as possible” you'll need to experiment and benchmark with your workload. Which filesystem is optimal may depend on how you are laying out the data and where the latency/throughput sensitivities are in your use case and the given filesystems. > My prime concern is having an api such as... Having a different API other than it looking like a filesystem would make cross-platform more of a concern, as you then have a data access library not a general filesystem. It will likely to be necessary for best performance though: any filesystem is going to have significant overheads (orders of magnitude) compared to being able to map chunks of the data directly into your process' address space. If abandoning a generic filesystem, perhaps something like sqlite with an in-memory table/db (https://www.sqlite.org/inmemorydb.html https://www.sqlite.org/inmemorydb.html)? Again like the ramdisk option just load up the content from permanent storage on first use.