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I've read this tutorial:

But I was wondering, if I want a daily backup and weekly backup as they suggest, I do need twice the amount of space of my data on my backup server ?

So if my adata are 500MB, I need 1GB of space (500GB for daily backups, and 500 for weekly backups ?)


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Yes, you'll need twice the space. If that's not acceptable, then you'll have to look for a backup solution a little more sophisticated than rsync, that will do proper differential backups and only store data twice if it's actually been modified.

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rsnapshot: Using rsync and hard links, it is possible to keep multiple, full backups instantly available. The disk space required is just a little more than the space of one full backup, plus incrementals.

I've got Rsnapshot's setup that will keep 6 copies/versions per day, 7 days a week, 4 a month and for as much as 6 months. While it will copy and store entire files, only a small portion of the total count of files would usually be changing on a regular basis.

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Have a look at BackupPC - it uses rsync as one of its backup tools but handles space very cleverly by hard linking between identical files in backup sets:

From the docs...

Features include:

  • A clever pooling scheme minimizes disk storage and disk I/O. Identical files across multiple backups of the same or different PC are stored only once (using hard links), resulting in substantial savings in disk storage and disk writes.

  • Optional compression provides additional reductions in storage (around 40%). The CPU impact of compression is low since only new files (those not already in the pool) need to be compressed.

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