Re: Some notes on RootOnZFS article in wiki

2009/12/21 Scot Hetzel <swhetzel_at_gmail.com>

> On 12/21/09, Mel Flynn <mel.flynn+fbsd.current_at_mailing.thruhere.net<mel.flynn%2Bfbsd.current_at_mailing.thruhere.net>>
> 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.
>
> I have updated the wiki to mention that you need an install media with
> the livefs support.
>
> >  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.
>
> I had marked that step as optional, and as was stated in this thread
> it is not needed for GPT disks.   This optional step has been removed
> from the wiki.
>
> >  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?
>
> To mirror the swap partitions, your will need to use gmirror.
>
> 1. comment out/remove the /dev/gpt/swap{0,1} entries
> 2. add geom_mirror_load="YES" to /boot/loader.conf
> 2. reboot to make sure the system is not using the swap partitions
> 3. create the mirrored swap partitions using the gpt/swap0 and
> gpt/swap1 partitions:
>
> gmirror label -b prefer swap gpt/swap0 gpt/swap1
>
> NOTE: round-robin can also be used, but see the gmirror(8) man page
> about kernel dumps.
>
> 4. change /etc/fstab to use the mirrored swap partition:
>
> /dev/mirror/swap                 none                    swap    sw
>          0       0
>
> If you try this, let me know how it turns out.
>
> Scot
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Are there still issues with using zvols for swap? If not you don't need a
slice for swap and can get rid of gmirror entirely.