Restic create big cache

[kapitainsky]

@zcalusic

The only question is why would anyone want to do such a silly thing

Only to see this edge case behavior:) Indeed it is unlikely in real life.

@yogasu data can for example generate massive metadata changes when yours not. There is no simple formula linking number of files to cache size.

Here you are example of metadata changes driven backup size (it of course results also with massive cache size):

Tracking down large metadata changes

I have a macOS 11.2.3 (but the problem persisted even with 10.4.6) client where every backup that’s taken every hour adds around 400-450 MB new data to the repository. I’m trying to nail down what it is that’s generating this much changed data, because the stuff the user herself changes shouldn’t be more than a few tens of MBs. I am able to reproduce the problem fully, by running a backup, and even if I do so with just a couple of minutes between the runs, the problem appears, although if I do …

So massive factor is how many files change - as it generates new metadata. So e.g. I backup 1 million files, they never change - 10 snapshots later I have 10m files in my repo but only 1m unique. Then in very different situation whith every file changing before taking new snapshot (even if it is only metadata change) I will end up with also 10m files in repo but metadata part will be many times larger.