Re: upgrade stable/12 -> stable/13 zfs + boot partition Mediasize 64K

On Thu, Feb 11, 2021 at 4:35 PM Russell L. Carter <rcarter_at_pinyon.org>
wrote:

> Greetings,
>
> I really want to jump from stable/12 to stable/13 but one thing is
> causing a hesitancy.  And that is, my main raidz2 system has
> a system boot zfs mirror pair that has boot partition size
> (Mediasize) of 64K, and when I tried to zpool upgrade that pool a
> year or 2 ago I got some scary message something like "boot
> partition size is not large enough".  I asked about this on the
> lists but never received an answer.  So, laziness required me
> to ignore the problem and not zpool upgrade any of my 15 or so
> zpools in the interim.
>
> A few weeks ago I tried to make buildworld/installworld upgrade
> 12->13 but the boot failed in the mounting filesystems phase with it
> couldn't find a bootable target.  So after restoring 12 I decided
> to wait a bit.  In the interim I have upgraded every zpool but that
> one system pool.  All the other freebsd-boot partitions have a size
> of 512K.
>
> So what is the current advice?  Is a freebsd-boot partition size
> of 64K laughably obsolete, and I should get with the program and
> repartition those disks, or can I march blindly into the upgrade?
>
> I guess I just want to understand where these sizes are going in
> the future.
>
> That is laughably small and you need to enter the 21st century.  ;)

I believe the recommendation is 256 MB or even 512 MB these days.

If you partitioned your disks using "-a 1M" with gpart(8) for the
freebsd-zfs partition, then you'll have some slack space between it and the
freebsd-boot partition. Just delete the freebsd-boot partition and create a
larger one in it's place.  I did something similar with some drives that
were part of a separate storage pool that I wanted to make bootable, by
creating a freebsd-boot partition in the slack space before the freebsd-zfs
partition.

If you don't have that slack space at the front, you will need to detach
one of the drives from the mirror, re-partition it, then attach it back to
the mirror.  Rinse and repeat for the other side.  ZFS shouldn't notice the
pool is smaller by 1 MB (there's some internal slack space to allow you to
add drives that are labelled as the same size, but actually have different
numbers of sectors).

Cheers,
Freddie