So what will happen if you are busy encrypting or decrypting a drive and there is a power failure that causes your PC to go down ? I tested this in my lab to see what will happen. When you install the TMEE (Endpoint Encryption) client, it installs a Service that boots up with the client. This driver is responsible for looking at the state of the encryption status on the hard drive.
So lets look at the first scenario : Rebooting while Encrypting
You just installed TMEE on the PC. It will do a reboot and then after that boot into the OS and start the encryption. Thus you can work while the drive is being encrypted in the backend. While it is encrypting you have a power failure. You then boot the PC. The Service will start up and see that the drive have stop encrypting and would then start the encryption process again. It will continue from where it stopped.
Scenario two : You are busy with a Recovery Console Decryption and Power failure
So you have booted into the Recovery console and busy with a decryption and there is a power failure. You boot back into the Recovery Console. From here you can start the decryption process again. TMEE will see that the drive is partially Decrypted and continue with the decrypt process. Note that the decryption process is not started automatically…you have to start it.
Scenario three : Busy with Recovery Console Decryption, power failure, power restored and then OS boots up…
Basically the same as scenario two, but you missed the “boot from cd” after the power failure and now the Windows OS boots with a half encrypted drive. Once the OS have booted the TMEE Service will detect that you have a half encrypted drive and start to re-encrypt the drive. Note that you were busy with a decryption…that does not matter. The TMEE Service will ensure that the drive gets encrypted again after the reboot. You will need to go into the recovery console and start the decryption again.
At any time you can open the Recovery Console and see what the status is of the encryption. See below :