Se o disco estiver completamente cheio, não. Há uma sobrecarga de pelo menos alguns megabytes para um volume criptografado.
Com a criptografia de todos os discos (dmcrypt), a criptografia de um volume existente não é suportada fora da caixa. No entanto, o luksipc (Ferramenta de conversão no local LUKS) automatiza o processo de criação de um pequeno volume criptografado, copiando um pequenos dados, aumentando o volume (sobrescrevendo o texto simples que acabou de ser copiado), e assim por diante, até que todo o volume seja criptografado. Vou citar o seu aviso:
Before you attempt to do anything with the device, be warned: You may lose some of your data, even all of it (for example if you put the LUKS device key in
/dev/shmand reboot your system before you add another key to the keyring). Power failures are also bad (since you will not have a resume file in that case). Furthermore, luksipc may have bugs that wreak havoc on your data. Also keep in mind that luksipc relies completely on a perfect disk. If your disk has read-problems, it likely will abort somewhere within the middle of the process (most likely also without creating a resume file). If your disk is faulty, get a new one instead of trying to crypt it. And, most importantly: Always have a backup. Now, let's be honest here: You probably don't have a backup. If you had the disk space, you wouldn't have the need to convert data in-place. Or maybe you have one and it's really old. Or the data is not really that important. In any case, please please please do not assume that everything will run smoothly. It may not. You have been warned. I will not be held responsible for any of your actions.That said let me point out that I trusted my software (after thourough testing) enough to let it convert a 1 TB partition without having a backup. This worked nicely. However, your milage may vary.