In Ubuntu... how much computer memory does each Timeshift record use up? And can the whole set of records or just one be deleted and if all, the space reserved for Timeshift be freed? If so, how?

In rsync mode timeshift basically initially copies all files based your settings and then only copies changed files. Each incremental backup contains the changed files and hardlinks from past backups for those unchanged files.

In the schedule section of timeshift you select how many backups to keep. I have not played with timeshift much so I don't know if deleting older backups from the cli will mess the hardlinks.

A follow-on to the previous thread - for which insufficient data was provided. Perhaps the OP should learn to search for, and read, documentation.

Timeshift has a GUI interface that makes all this obvious - space reclamation on backup removal is entirely site specific. Any or all can be deleted at any time - old(-est) ones is obviously more sensible.

I've got Timeshift set up to keep three weekly backups, the incrementals. Their size will depend on what files have been changed since the previous backup. My original backup, the epoch or initial backup, will depend on what directories and files you decide to backup. After each weekly incremental completes the oldest one is deleted automatically.

My Timeshift backup partition is on a second drive; USB external, and at 750Gb is waaaay to big. Putting the Timeshift partition on your primary drive isn't going to help you if it fails! I assume you mean disk space when you say "memory."

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