Pool disappears after reboot, previous partition (whatever it is) reappears instead

[ggrocca]

Mojave 10.14.6, OpenZFS installed with brew (OpenZFS on OS X 1.9.4 Mojave.pkg)

By "disappears" here I don't mean "it's not imported", I mean actually, really disappears (no output from zpool import). The problem - on that particular machine at least (a macbook pro 13 unibody), and on that specific partition - is reproducible. I create, I reboot, nothing is there anymore.

It happens on a SSD partition (disk0s3). Previous partitions are: disk0s1 EFI, disk0s2 APFS with the OS. There's also another internal disk (disk1, HDD, entirely devoted to ZFS), plus a bunch of usb disks with ZFS, no problem there.

Whenever I reboot, disk0s3 reverts back to whatever partition was there before creating a ZFS pool in its place, be it a fat32 one or a HFS one or whatever.

I've tried to search here and on the internet, but I found nothing and I got no effin' clue to whatever's going on. My search results are obscured by people that cannot find their pool because it's not automatically imported, but this is not my case at all. This is not the only macOS machine on which I use ZFS - on one machine in particular I have exactly the same configuration, with a pool on a SSD partition and a pool on a whole magnetic disk. I use ZFS on Linux too, and it's the first time I encounter a situation like this.

If anyone has any ideas about how to proceed, I would be grateful. I don't have specific knowledge about ZFS internals, but I'm a software developer and I'm comfortable with the command line, so if there's debugging to do, I might try it if there are instructions to follow.

[ggrocca]

This was way simpler than I thought. Thanks to a kind user in the OpenZFS on OSX forum, I've discovered that the problem was that a while ago it became mandatory to manually set the partition type to bf01 when creating a pool on a slice. I've posted a full solution on super user, for future reference to anyone that arrives here because of a similar problem. I'm closing the issue (it wasn't a issue to begin with).