Two levels of backup.<p>1. Daily backup. Personal documents take up one directory tree amongst the many directory trees of my /home/username directory which is backed up in full every day. Those daily backups are discarded in a reverse-exponential way, such that there many recent backups and fewer older backups.<p>Those daily backups are duplicated twice more on to two separate external hard drives.<p>2. Monthly backups, documents only. The whole of my documents directory tree is tarred and compressed as a monthly 'snapshot' and this is stored as three separate instances on three separate hard drives, one internal and two external. Those monthly backups are stored indefinitely and never discarded.<p>NOTE: I know I should have another copy stored off-site as 'belt and braces', but I know from painful experience that 'cloud storage' can be less dependable than a home-grown solution. And the triple-copy on-site system has served me well so far.