gptboot: invalid backup GPT header

John freebsd-lists at
Mon Nov 3 01:44:00 UTC 2014

On Sun, Nov 02, 2014 at 07:15:59AM -0700, Warren Block wrote:
> Clearing the last blocks will remove the warning, at least if the 
> assumption is correct.  ZFS is not supposed to be using the last 
> portion of the disk(*) to make replacing disks of slightly different 
> sizes easier.  Still, I would back up either the whole array, the 
> whole disk, or at least the last 33 blocks of mfid1 first.

Thanks for replying. So, in short - is my data on the array in any 
danger, or is this just a cosmetic issue?

[I think the reason it happened is that during the install process, 
where the installer asks you to choose partitions, I removed 
*everything* from mfid1,2 & 3 as I knew zfs likes to deal with the raw 
disk. I don't want to have to blat the system again though, unless 
absolutely necessary].


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