ZFS & proxmox-boot-tool


Apr 22, 2019
I installed Proxmox 7.x through the ISO on a Hetzner test server on ZFS with 4 HDDs. When upgrading to Proxmox 8, I encountered the documentation on switching to proxmox-boot-tool again (https://pve.proxmox.com/wiki/ZFS:_Switch_Legacy-Boot_to_Proxmox_Boot_Tool) but I'm not sure if I'm understanding it correctly or if I need it.

The current system is booted in legacy boot mode, and it appears to work fine. Unfortunately I did not note the version of grub installed before upgrading, so now it's the version contained in Proxmox 8. The guide to switching to proxmox-boot-tool implies that there should be a separate partition of 512M usable to convert to UEFI boot, but my partition structure looks different and I don't recall changing anything on purpose:

Device Start End Sectors Size Type
/dev/sdd1 48 2047 2000 1000K BIOS boot
/dev/sdd2 2048 4196351 4194304 2G Solaris /usr & Apple ZFS
/dev/sdd3 4196352 31251759070 31247562719 14.6T Solaris /usr & Apple ZFS

part2 on each disk is added into a 'bpool' zpool, and part3 is used for the ZFS rpool. Disks are using GPT disk labels.
To me, it looks like part1 is not used/needed at all, part2 is way oversized for /boot, and there is no "placeholder" partition for UEFI boot.

As this is more of a home lab server, I did not document my installation settings as diligently as I would have for production systems, so I'm hoping somebody can help me understand:

- Where does this part1 "BIOS boot" partition come from? How do I figure out if I actually need that?
- Did I misconfigure something in Proxmox / ZFS and should part1 be the ZFS bpool and part2 the potential UEFI placeholder partition?
- If the system boots and runs fine, does it even make sense to migrate to using proxmox-boot-tool?
- If yes, what would I need to look out for? I assume I would have to resize the bpool partitions and create a new UEFI partition on each disk?

Thanks in advance for any help - I am a bit stumped how to dig further here and don't want to risk making the server unbootable.


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