CODEWITHSUNDEEP
backuprsyncrollback
puk
puk

Reputation: 16782

Does rsync make a backup copy or a history of backup copies?

Many tutorial sites mention making hourly/daily/weekly backups with rsync [1], [2], and even more claim to set up rsync like Mac's Time Machine [3], [4], [5]. But when I look at the code, it seems like they make currentBackup/ folder, next time around they rsync against this currentBackup to only copy over the changes necessary, then delete the currentBackup and set the new folder to be currentBackup. But what if I want daily backups likes so

March-10-44-BC/
March-11-44-BC/
March-12-44-BC/
March-13-44-BC/
March-14-44-BC/
March-15-44-BC/

So on March 16 I can 'roll back' to the March 15 version or the March 14 version. I have noticed each site mentions something called hard links. Since I can't understand what this is, perhaps this retains information capable of performing 'roll backs'. If not, what am I supposed to do? Keep all previous backups and tar.gz them?

Upvotes: 2

Views: 2842

Answers (1)

blahdiblah
blahdiblah

Reputation: 34011

For these purposes hard links serve as "copy on write" copies of the files. If a file is unchanged, hard linked "copies" of it don't take up any extra space. When the file is changed, because of the hard links, a new copy with the changes is created instead. See Wikipedia for more information.

So rsync does mainly backup, but can provide some archiving functionality as well. This is in contrast to other backup software like Time Machine that always and automatically provide archiving as well as backup.

Upvotes: 2

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