I am looking for a convenient solution to the following problem:
I have some large data (tens of GB) that resides on the hard drive of a Mac. Access to the data needs to be restricted so even users with administrative privileges can't access it without a password. At the same time, those people who do have access should have convenient and fast access: ideally, after unlocking them, the restricted files should be visible and accessible in the same way as any other file on the system. It must be possible to run programs that process the data and accessing the files should not be much slower than usual file access. Only read access is needed, not write access.
What sorts of convenient solutions are possible on a Mac (OS X 10.9)?
Is it for example possible (or advisable) to put everything in an encrypted DMG disk image? It could be mounted after entering a password and used as a normal volume afterwards, but I'm not sure if other users who are logged in at the same time will be able to access it. I am not deeply familiar with Mac specific technologies. I understand that usually there is a tradeoff between security and convenience.