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I have recently decided to encrypt my Gentoo Linux installation. I am going to use cryptsetup with LVM. LVM filesystem will be placed inside encrypted dm-crypt partition. I have problem with forgetting passwords. I don't want forget password to cryptsetup because I can lose all of my data. I'd prefer hold backups on encrypted external hard drive. How is your recommends to choosing a good password for full disk encryption? I'm not sure if backup unlocking key on USB will a good idea because in case of necessity of disclosure data and disk keys or passwords I would like to prevent beware leaking it.