Asynchronous file IO in .Net

I'm not sure I see why option 1 wouldn't work for you. Keep in mind that you can't have two different threads trying to use the same FileStream at the same time - doing so will definitely cause you problems. BeginRead/EndRead is meant to let your code continue executing while the potentially expensive IO operation takes places, not to enable some sort of multi-threaded access to a file.

So I would suggest that you seek and then do a beginread.

What we did was to write a small layer around I/O completion ports, ReadFile, and GetQueuedCompletion status in C++/CLI, and then call back into C# when the operation completed. We chose this route over BeginRead and the c# async operation pattern to provide more control over the buffers used to read from the file (or socket). This was a pretty big performance gain over the purely managed approach which allocates new byte[] on the heap with each read.

Plus, there are alot more complete C++ examples of using IO Completion ports out on the interwebs

What if you loaded the resource (file data or whatever) into memory first and then shared it across threads? Since it is a small db. - you won't have as many issues to deal with.