GEOM: the primary GPT table is corrupt or invalid after RAIDZ creation

[a.smith at ukgrid.net]

Hi,

  Looks to me like you are creating 4k aligned partions (adxp1) and  
then not using them.
I think you need to do:

gnop create -S 4096 ad6p1 (you have 4086 so hopefully just a typo from you)
zpool create raidz tank ad6p1.nop ad8p1 ad10p1 ad12p1 ad14p1

Using adx[.nop] at the zpool create stage is using the whole usable  
disk, not the aligned GPT partion you went to the trouble of creating  
(gpart add -t freebsd-zfs -b 2048 ad6).

cheers Andy.