Backup only 1% smaller than the original

Getting Help
1 
> restic version
restic 0.18.1 compiled with go1.25.1 on windows/amd64

Somehow my ~11TB backup that took 24 hours ended up being essentially the same size as the original data despite deduplication and max compression. Here’s the command I used:

> restic --repo MyBackup --compression max --option local.connections=1 --read-concurrency 1 backup --no-scan E:\Archive E:\Docs E:\Media...

Strangely enough, it seems auto compression was used despite me specifying max?

> restic --repo MyBackup stats --mode restore-size latest
enter password for repository:
repository 7e3b08e1 opened (version 2, compression level auto)
[0:09] 100.00%  203 / 203 index files loaded
scanning...
Stats in restore-size mode:
     Snapshots processed:  1
        Total File Count:  1383286
              Total Size:  10.990 TiB

> restic --repo MyBackup stats --mode raw-data
enter password for repository:
repository 7e3b08e1 opened (version 2, compression level auto)
[0:08] 100.00%  203 / 203 index files loaded
scanning...
Stats in raw-data mode:
     Snapshots processed:  1
        Total Blob Count:  8932672
 Total Uncompressed Size:  10.716 TiB
              Total Size:  10.607 TiB
    Compression Progress:  100.00%
       Compression Ratio:  1.01x
Compression Space Saving:  1.01%

Is this just a case of unrealistic expectations or did I mess up somewhere? I know for a fact there are dupes and near-dupes on the drive, and all the deduplication and compression benchmarks and posts I came across show far better savings, even ones where restic didn’t come out the winner.

2

Please paste the output from the backup command run.

Also, what data is that? Seems like a lot of binary and hard to compress and deduplicate data, even if you say you have some of that too.

3

Is the output saved anywhere? I checked in AppData\Local\restic for logs but couldn’t find any.

Are things like docx and pdf considered binary? It’s a mix of documents and media. Although the majority of space is definitely taken up by media (pictures, audio, video).

4

Restic outputs to standard out. If you execute restic in the terminal, you will see the output there, like in your examples. If you execute restic some other way, where the output ends up is entirely up to you or that other way – restic just emits output and whatever calls or executes it is responsible for making use of that output.

Generally speaking, as you probably already know :), binary files are not very compressible, and if I’m not mistaken .docx files are already zipped up or something like that (you can open a .docx file in a plain text editor to check this yourself).

If I were to guess this is simply a matter of the data you backed up not lending being very suitable for deduplication and compression. Media files generally don’t compress or deduplicate well. I don’t see anything obviously wrong anywhere.

Regarding compression, I’m pretty sure that you did get max compression, because the compression level is specified per command, so if you specified max compression when you ran the backup then that ought to be what was being used. The output from that run would say which level was used.