ZFSBoot try and bsdlabel bootstrap code

[Doug Rabson]

On 13 May 2009, at 09:29, Randy Bush wrote:

> next week, i have to do a system install on a 24tb array which has no
> cdrom.  i want to use raidz2.  the new issues to me are
>  o install from usb stick
>  o installing on a new zfs
>  o boot from zfs
>
> i have a couple of systems where i did a small bootable gmirror
> partition on the first two drives, and then gave the rest of the  
> drives,
> and other whole drives, to zfs.  i could do that this time too, i
> guess.  but i wondered if i could do an install which was pure zfs.
>
> i have been collecting email on the subject for six months.  so now i
> have some clues and some confusion.  is there a zfs capable loader?
>
> i will be doing this a jet-lagged.  is there a recipe?

There is basic support in the FreeBSD-current tree which covers  
booting from simple disks, mirrors and collections of mirrors. I have  
patches for raidz and raidz2 but they really aren't ready for prime  
time (they work in small test cases but not for larger real-world  
arrays).

What you could do to allow the installation of ZFS boot code in the  
future is use GPT to partition the drives and create a small boot  
partition. Something like this:

	# gpt create -f da0
	# gpt boot -b /boot/pmbr -g /boot/gptzfsboot da0
	# gpt add -t freebsd-zfs da0

The bootstrap code in /boot/gptzfsboot doesn't currently support raidz  
or raidz2 but initialising the array this way will make it easier to  
install a functioning bootstrap at a later date.