On 01/17/2012 10:31 PM, Marc Schwarzschild wrote:
Thank you. I gather from this that I can safely halt or reboot while a disk is mounted, right?
From the LUKS metadata point of view yes (there will be still encryption key in memory but that's different problem). From the filesystem POV above LUKS - it depends. If it is remounted read-only, there should be no data loss on [un]expected reboot. (If you reboot while some write IOs are in-flight, of course you get some corruption.) Anyway, distro initscripts should handle this during controlled shutdown for all mounted devices. Milan
--- January 17, 2012 Milan Broz sent: --- On 01/16/2012 03:48 PM, Marc Schwarzschild wrote: > I am setting up an external USB encrypted drive. I can mount it > manually after I boot the computer. I understand that I must > issue the 'cryptsetup luksClose' after I umount the disk. How do > I arrange for this as part of the Debian halt process so it > happens automatically when the server is shutdown? It is not cryptsetup job, it should be part of initscripts/systemd to correctly unmap active devices on shutdown. (Usually it tries to unmap all crypto disks except device with root fs which is just remounted read-only. Recent systemd is able to unmouteven root device properly.) For hot-plugged disks it is usually handled by some GUI service, usually based on udisks. > What happens > if there is a power failure and 'cryptsetup luksClose' was not > executed? For LUKS, no need to worry after power failure - luksClose just remove kernel mapping (kernel state) it doesn't touch on-disk metadata at all. (Of course there can be some filesystem damage after power failure, but that's not LUKS related, it can happen even for unencrypted fs.) Milan
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