Systemd boot for ZFS installation - grub fallback option?

AveryFreeman · 2017-12-27 23:57:23

Hello,

I'm interested in switching to systemd boot so I can make use of https://github.com/dasJ/sd-zfs

However, I'm worried about performing the switch.

Has anyone ever done this that can tell me what I can do in the event of a failure? Is there a way I can boot to a ZFS volume without grub if systemd-boot doesn't work / is configured incorrectly? Most 'rescue usb' or 'live usb' packages don't support ZFS...

Thanks

jasonwryan · 2017-12-28 00:01:18

Not an Installation issue, moving to NC...

seiichiro0185 · 2017-12-28 05:57:53

It very much depends on the kind of failure you are seeing. For a misconfigured systemd-boot entry, you can edit the entry right from the boot menu (as long as you don't disable this option) as you can with grub. If systemd-boot is completely broken (e.g. you don't get to any Menu / CLI at boot) you will need a livecd / usb (but thats the same with grub). Also editing the bootentries / systemd-boot config should be possible with any kind of LiveUSB/CD, since they need to reside on the (FAT32-Formated) EFI System Partition. Since Kernel and Initrd also need to be on a Partition readable by systemd-boot (which doesn't know ZFS) you also have the initrd rescue shell in case your bootentry works but something goes wrong mounting the ZFS root.

I used this setup for quite some time and never had a problem with it (Now using btrfs since I don't use any raid (Laptop only has one SSD anyways) and I don't have to mess with the out-of-kernel modules)

For LiveCDs with ZFS included you can always build your own archlinux iso with ZFS-Support using archiso. Also AFAIK the (Archlinux based) Antergos Live/Install CD has ZFS support built in.

AveryFreeman · 2017-12-28 14:56:00

@jasonwryan thanks, I wasn't quite sure which forum would be best
@seiichiro0185 I will have to do more research on how ZFS support is implemented for the boot process - it's installed in the vmlinuz by using hooks in mkinitcpio.conf, right?

does systemd-boot used the same initramfs images that grub does? So many questions ... must more google ...

Thanks, that's a great starting point. I'm sure I'll have more questions soon ...

seiichiro0185 · 2017-12-29 15:21:55

basically boot is like this:

bootloader -> kernel (vmlinuz-linux) -> initrd (initramfs-linux.img) -> rootfs

kernel +initrd are the same regardless of bootloader, so systemd-boot or grub makes no difference as long as kernel and initrd are outside of the zfs root.

Mounting of the zfs root happens in the initrd trough the hooks configured in mkinitcpio.conf

Arch Linux

#1 2017-12-27 23:57:23

Systemd boot for ZFS installation - grub fallback option?

#2 2017-12-28 00:01:18

Re: Systemd boot for ZFS installation - grub fallback option?

#3 2017-12-28 05:57:53

Re: Systemd boot for ZFS installation - grub fallback option?

#4 2017-12-28 14:56:00

Re: Systemd boot for ZFS installation - grub fallback option?

#5 2017-12-29 15:21:55

Re: Systemd boot for ZFS installation - grub fallback option?

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