Question about Compacting

I have to decide about the off site volume for safety backups. To avoid to buy to much volume I wonder how many percent Duplicati shrinks the stuff it backs up.
I.e. I have about 3 Tb of stuff (mainly professional photo’s). How large will the Duplicati backup be?
Thanks for a reply.
Stay healthy and have a nice day,
Johan Hahn

There is no way to know in advance. The amount of back end storage required depends on several factors: your data files, how often you do backups, the data change rate, and your retention.

If you must know before you buy storage, you could consider backing up your data first to a local destination, as a test.

By the way - for a 3 TB backup I would recommend you use a deduplication block size of 1-5 MB (the default is 100Kib – too small for a 3 TB backup).

Welcome to the forum @Johghahn

What does that imply? Are they RAW images? If they’re already compressed, e.g. JPEG they won’t be compressed again because there’s no point. You do have some control via compression-extension-file.

Apparently even RAW images can be compressed, and this may depend on your camera and settings.

Compressed vs Uncompressed vs Lossless Compressed RAW Options
Which Image Format is Better —RAW vs. JPEG?

Deduplication will probably not help much between photos unless they’re duplicates. Data is too varied.

Beyond the great advice from @drwtsn32 you might also consider a provider that permits expansions.
You may be able to ballpark current size extrapolating from small sample test, but size grows over time.

Thanks for the info!
Have a nice day!
Johan Hahn (NL)

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