As an alternative to using encrypted disk images, I created a FileVault 2 encrypted partition in Lion for some important data on the SSD in my MacBook Air. The password is not stored in a keychain. Once it is unlocked, I can unmount and mount it again without authenticating, even after logging out and back in again. Nothing short of restarting seems to lock this partition again.
Re-locking an internal encrypted partition while logged in is possible in other implementations of whole-disk encryption, and for FileVault 2, according to the man page for diskutil, specifically, for the command
diskutil coreStorage unlockVolume,
"This verb unlocks an LVF by providing that authentication; as the LVs are thus appear
as dev nodes, any file systems upon them are automatically mounted. To "re-lock" the
volume, make it offline again by ejecting it, e.g. with
While this does work as it should with encrypted external drives, it does not seem to work on my encrypted internal partition. I can eject the logical volume, which is /dev/disk1, but it does not get locked. Trying to eject its containing Logical Volume Family, Physical Volume, or Logical Volume Group, results in errors, even using administrator privileges. I tried variations, using unmount, unmountDisk, referring to the device UUIDs, with no luck. What am I doing wrong here?