> The command told it to reattach the drive and they expected it to rebuild but instead md saw part of the mirror and simply added the drive as a good drive.

> ZFS catches these tricks because the checksums will fail.

Yea, I think this is the right explanation. I guess it simply doesn’t keep any consistency information that it can check, whereas ZFS keeps a checksum of every block. Having used ZFS, it is difficult for me to understand how anyone could trust anything else. I don’t think that there is anything a ZFS user could do to accidentally destroy their data (aside from obvious things such as deleting the wrong filesystem or pool, which could happen in any case).