Aligning MBR for ZFS boot help

[Warren Block]

On Sun, 10 Mar 2013, Adam Nowacki wrote:

> I don't think zfsboot is aware of BSD disklabel (offsets other than 0 won't 
> boot). Is there any reason you are using BSD disklabel and not two partition 
> MBR?

MBR slices created on FreeBSD are forced to CHS alignment, pretty much 
always misaligned for 4K-block hard drives or SSDs.

> I also don't think there is any merit in aligning to 1MiB. Most ZFS IOs will 
> be aligned to sector size (ashift). Unless ZFS pool is created with higher 
> ashift then the 63 sector offset is as good as any.

If the drive has 4K sectors, that will be misaligned, potentially 
cutting speeds drastically even if ashift is 9.