gmirror on different sized disks

[Doug Poland]

Hello,

Until just a few moments ago, I thought I had identical sized drives
(arrays, really) on my i386 6.1-STABLE box.

I was trying to create a gmirror on ar1 from ar0 when gmirror reported
to me:  Provider ar1 too small.

my dmesg reports:
ar0: 152638MB <Promise Fasttrak RAID0 (stripe 128 KB)> status: READY
ar1: 152637MB <Intel MatrixRAID RAID0 (stripe 128 KB)> status: READY

So it would seem I'm 1MB away from being able to create a "whole disk"
mirror of ar0 on ar1.

Is my only recourse to mirror individual slices, as described in
http://people.freebsd.org/~rse/mirror/ ??

Thanks for any help/pointers/suggestions.

-- 
Regards,
Doug