[tandr]

I'm thinking about using this and have a few questions:

    1. How are hardlinks and duplicate files (same content, different paths) handled?
    2. Does deduplication work on a block/chunk level for partially matching files, or does it only look at whole files?
    3. Is there any specific integration or handling for Copy-on-Write (CoW)?

Thank you!

[pierrebarre]

Hardlinks work as you’d expect: multiple paths point to the same inode and data, so a write through one path is visible through the others. Two separate files with the same contents are stored separately.

There’s no deduplication, either whole-file or block-level. That’s intentional, mostly because of the impact it would have on locality.

If by CoW you mean reflinks, those aren’t currently planned either. They avoid the content matching part of deduplication, but still require sharing extents between files and come with similar locality and complexity tradeoffs. Internally ZeroFS is copy-on-write, with immutable segments and checkpoints, but that isn’t exposed as reflinks.

[tandr]

Thank you for the quick answer.