Some notes on RootOnZFS article in wiki

Robert Noland rnoland at
Mon Dec 21 15:21:29 UTC 2009

On Mon, 2009-12-21 at 06:00 -0900, Mel Flynn wrote:
> Hi,
> yesterday went through the RootOnZFS (gpt mirror version) and here's a few 
> notes:
> 1) You cannot use the install CD. It doesn't have a livefs and so you can 
> never do the actual install in 2.2. The DVD will work and the USB image. I 
> ended up using the livefs CD and the USB image, cause I didn't want to loose 
> the work I already did.
> 2) `gpart set -a active -i 1 ad4' gave me 'active: device not configured'. 
> This error isn't mentioned (debugflags didn't help) in the wiki nor the 
> missing DIAGNOSTICS section in the gpart man page. In my case the system 
> booted, but it's nice to know what the error means and whether you can ignore 
> it.

This step *was* only required for some BIOS and I'm not sure that it
ever worked as above.  Previously, I had to use fdisk to set the active
bit in the PMBR.  In at least 7-STABLE+, installing bootcode via gpart
will set the active bit in the PMBR, so this step is never required.


> 3) By adding the swap partitions on the two mirrored disks to /etc/fstab top 
> actually shows the sum of these as available swap. My expectation is/was that 
> the swap would be mirrored and thus I'd have only the size of one swap 
> partition. If this isn't the case, can I get by with 1 of the two since 
> they're double the intended size or should one use 2 and thus create them half 
> the intended size?
> 4) The given mount points have sane defaults, however, I use cvs to checkout 
> the ports. It would be nice to have one example where data is already in a 
> directory tree and how one can promote it to a zfs filesystem with special 
> properties.
> Thanks to everyone contributing to this article and keeping it current, bar 
> the installation media, everything was a breeze!
Robert Noland <rnoland at>

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