Comment by magicalhippo

4 hours ago

> Can you give a more concrete example of what you mean?

There's been several instances. For example, the send/receive code has had bugs leading to cases[1] where the checksum and hence scrub look fine but the data is not.

edit: the recent block cloning has also had some issues, eg[2][3].

I'm pretty sure it's also possible for hardware errors like bad memory to cause the data to get corrupted but the checksum gets computed on the corrupted data, thus it looks ok when scrubbed.

[1]: https://github.com/openzfs/zfs/issues/4809

[2]: https://github.com/openzfs/zfs/issues/15526

[3]: https://github.com/openzfs/zfs/issues/15933

2 comments

magicalhippo

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mustache_kimono  36 minutes ago

> There's been several instances.

I think you're missing the 2nd feature to the parent's point that I take issue with, which is this is not just a bug that a scrub wouldn't find, but it must also be a bug which an fsck would find.

The parent's point is -- ZFS should have an fsck tool because an fsck does something ZFS cannot do by other means. I disagree. Yes, ZFS has bugs like any filesystem. However, I'm not sure an fsck tool would make that situation better?