Chunk size setting


I have the following use case :

Each time I download on my PC a lot of new photos from my camera, I backup them immediately. Later, gradually, I set metadata on the photos (title, location, etc…). And then I backup them again.

The average size of my photos is 6-10MB.

With Borg I can set the chunk strategy so this new backup doesn’t increase the backup size so much. With Kopia, the backup size increases as if I had added new photos. In others words, if I modify the metadata of a 8MB photo, the backup size increases by 8MB.

Are there some evolutions planned on this topic ?

Thanks for any answer.

This does not sound right. Kopia only backs up changed chunks. What splitter algorithm are you using with Kopia?

Kopia only backs up changed chunks.

Yes, but I suppose that if the chunk size is larger than my photo, it creates a new chunk, even if I have modified only a few Kbytes of metadata into the photo.

What splitter algorithm are you using with Kopia ?

I don’t understand this question : I didn’t find any “splitter algorithm” choice into KopiaUI.

You can see the splitter algorithm option under Repository. It is set when you originally create a repository, so you likely are using DYNAMIC-4M-BUZHASH if you did not change it. You can change this to a smaller chunk size, but you will need to recreate the repository as far as I know. There are also performance tradeoffs with using smaller chunks (see the discussion at Deduplication efficiency), but if most of your files are small, then you may benefit from a smaller chunk size.

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Thank you very much for this answer !

I will try it.