Aligning MBR for ZFS boot help

[Cody Ritts]

Offsetting the zfs slice, was one of the the first things I tried, but 
when I boot the loader tells me:

  > zfsboot: No ZFS Pools located, can't boot

I get the feeling that these need to be next to each other
   dd if=/boot/zfsboot of=/dev/ada0s1 count=1
   dd if=/boot/zfsboot of=/dev/ada0s1a skip=1 seek=1024

Good idea on using another fdisk.  I will fire up Arch and give it a go. 
  That will also let me test if the system will not boot with any GPT, 
or of there is something specific to FreeBSDs.  Once I isolate it, I see 
if I can figure out how to make a bug report to Foxconn.

And putting things in perspective, 63M out of 65536M is really nbd.  I 
wish I would have thought of that, so simple.  I guess my head is still 
stuck in 1996 when drives were still measured in MB :)

Thanks,

Cody


On 3/10/13 9:22 AM, Warren Block wrote:
> On Sat, 9 Mar 2013, Cody Ritts wrote:
>
>> Poking around on the internet, it looks like gpart is possibly
>> enforcing geometry boundaries?
>
> Not gpart, but the kernel.  At present, I don't know of any way to use
> FreeBSD for creating MBR slices aligned to anything other than 63
> blocks.  FreeBSD partitions can be aligned inside a slice with an
> offset.  Putting ZFS on one of those partitions may be the easiest way
> to do this.  Put the slice at block 2016, then align the first FreeBSD
> partition inside that slice to 1M and it should land at block 2048.
>
> Another option is to create the MBR with aligned slices using another
> operating system, one that allows deviation from the MBR standard.
> Ronald Guilmette recently showed an interesting approach of starting the
> slice at 63M, the least common multiple of 63 and 1M.
>
> If the BIOS does not like GPT, check for BIOS updates.  And make sure
> the vendor knows about the problem.
>