ZFS and zpool mistake

[Matthias Fechner]

Dear list,

I installed a freebsd with freebsd on a zfs root and only one disk:
  pool: zroot
 state: ONLINE
  scan: none requested
config:

	NAME         STATE     READ WRITE CKSUM
	zroot        ONLINE       0     0     0
	  ada0p3     ONLINE       0     0     0

This disk was now insterted into the computer and boots fine.
The next step I wanted was to setup a mirror with a second disk.

So I inserted a second disk, configured everything with gpart and added
the disk to the zroot with:
zpool add zroot gpt/disk1
(I think I had to execute zpool add zroot mirror gpt/disk1, this is not
clear from the man page)

And now I have a problem, it seems not to be a mirror but a stripe:
	NAME         STATE     READ WRITE CKSUM
	zroot        ONLINE       0     0     0
	  ada0p3     ONLINE       0     0     0
	  gpt/disk1  ONLINE       0     0     0

Is there any chance to get it into a mirror?

I don't think there was anything written to the second disk but I cannot
remove it anymore.

Has anyone a tip for me, howto convert the stripe to a mirror?

Thanks,
Matthias

-- 
"Programming today is a race between software engineers striving to
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produce bigger and better idiots. So far, the universe is winning." --
Rich Cook