Repository x3 place then biggest snapshot

[kvetals]

I have repository from Windows backup, which looks like this:

as You can see the biggest snapshot size is 844GiB but the size of the repository on disc is 2.3TB
I’ve tried several command from other topics

restic.exe stats --mode raw-data
repository 8b09418a opened (version 2, compression level auto)
[1:05] 100.00%  1509 / 1509 index files loaded
scanning...
Stats in raw-data mode:
     Snapshots processed:  10
        Total Blob Count:  1127871
 Total Uncompressed Size:  686.211 GiB
              Total Size:  652.053 GiB
    Compression Progress:  100.00%
       Compression Ratio:  1.05x
Compression Space Saving:  4.98%

and

stats --mode restore-size
repository 8b09418a opened (version 2, compression level auto)
[0:03] 100.00%  1509 / 1509 index files loaded
scanning...
Stats in restore-size mode:
     Snapshots processed:  10
        Total File Count:  5248099
              Total Size:  3.472 TiB

I suppose that repository should have the same size as seleced files for the backup or even less (because of archiving during backing up) but as a result:
snapshot size: 844 GiB
disc space: 2,4 TiB
total size: 3,4 TiB (it looks like similar calculation of snapshot sizes: 147 GiB * 7 snapshots + 844 GiB * 3 snapshots = 3554 GiB
Can anyone explain if this backup looks normal or not?
And How to find out where that additional size (2,4 TiB - 844 GiB = 1613 GiB) come from?

[minesheep]

Have you tried to run restic prune? That should remove data not used by snapshots (old data for example).

[kvetals]

Thanks, I think it will solve the problem:

But repo is new there should be no “old” files…
How that could happen and how to prevet that in future? Any idea?

[martinleben]

You have a number of snapshots. Inspect the differences between them and see if there are many temporary files etc in there which you might want to exclude from future backups.

[GuitarBilly]

hello @kvetals
Restic repository size from a high level view:

1. If your data does not really change then your repository size will not change much and approximately equal or smaller (depending on compression) than your original data.

2. However, your repo size can be much much bigger than your local data if your data is changing regularly. Restic will hold all data in the repository until you remove it, i.e. via prune or via retention rules.

Now in your case there seems to be discrepancy between the actual reported disk size of the repo (2.4TiB) and the actual repo size reported by restic (raw, 652 GiB).

You already found out that Prune wants to delete ~1.6TiB data, that is about the delta between the two.
As to where that data comes from you should know best. My best guess is that you have done some partial or interrupted backups inbetween from another source. If the backup is not completed it will not show up in the snapshot list but Restic will keep all partial uploaded data until you prune it.

Hope this helps.