Date: Mon, 10 Mar 2014 12:51:46 -0700 From: <dteske@FreeBSD.org> To: "'David Christensen'" <dpchrist@holgerdanske.com> Cc: dteske@freebsd.org, freebsd-questions@freebsd.org Subject: RE: FreeBSD 10 installer and ZFS root Message-ID: <1cb801cf3c9a$2c7e7970$857b6c50$@FreeBSD.org> In-Reply-To: <531E0287.6060907@holgerdanske.com> References: <53197EF6.4070902@holgerdanske.com> <5319913D.4040207@infracaninophile.co.uk> <10334f5b74b05d9445d071bd08f73a24@dweimer.net> <531A0A0B.3010902@holgerdanske.com> <eca03739afb425884241ed23c4202a7b@dweimer.net> <531D51EF.1080804@holgerdanske.com> <531D6737.4020708@infracaninophile.co.uk> <531E0287.6060907@holgerdanske.com>
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> -----Original Message-----
> From: David Christensen [mailto:dpchrist@holgerdanske.com]
> Sent: Monday, March 10, 2014 11:21 AM
> To: freebsd-questions@freebsd.org
> Subject: Re: FreeBSD 10 installer and ZFS root
>
> On 03/10/2014 12:18 AM, Matthew Seaman wrote:
> > On 10/03/2014 05:47, David Christensen wrote:
> >> Question -- do I need to make swap size equal to or larger than RAM?
> > No. You don't /need/ to do this, especially nowadays with machines
> > having large amounts of RAM (by which I mean much more than just 4GB,
> > which is a fairly routine amount nowadays). In your case I'd advise a
> > swap size of something between RAM+delta or 2 x RAM. 4GB is about the
> > minimum you can run a serious ZFS based server with, although for
> > light duties or experimental purposes you can manage ZFS with much less
> RAM.
>
> Thanks for the reply. :-)
>
>
> Okay. That's the old-school swap size calculation -- I'm surprised the
installer
> defaulted to 2g.
>
>
> > I wouldn't make ada0s1a a ZFS partition if all it is intended to do is
> > hold an unencrypted /boot -- UFS gives you everything you need for that
> > use case, and all the extra ZFS goodness isn't really relevant there.
>
> The installer made that decision.
>
[Devin Teske]
The installer makes ada0s1a a mirrored vdev so that any disk in the pool
can be booted from. Imagine what would happen if you had only a single
boot partition that was not mirrored and you lost that drive?
>
> >> ada0 is the raw block device.
> >> ada0s1 is a primary partition table entry pointing to an extended
> >> partition table.
> >> The extended partition table contains partitions ada0s1a, ada0s1b,
> >> and ada0s1d.
> > Yes, that is correct.
>
> Okay.
>
>
> >> Question -- can I adjust the size of ada0s1a and ada0s1d during
> >> installation?
> > I take it you mean 'can I install using different partition sizes?'
> > rather than 'can I change the sizes of the partitions after the fact?'
>
> Yes.
>
>
> > The installer contains a pretty reasonable partition editor, or it is
> > entirely possible to boot the install media to a live FS and set up your
> > drives from the command line, and then continue the installation using
> > the installer.
>
> I assume that the installer is a collection of shell scripts driving
> statically-compiled utility programs (everything in BusyBox?), and that
> the various command sequences and options are encoded in the scripts.
> Some options are made visible through the UI (swap size, boot
> encryption, 4K alignment of pools, etc.). I was hoping for a simple way
> to adjust other options, especially boot partition size.
>
>
> Looking at the amount of work the installer ZFS partitioning sub-system
> does, I'd rather not attempt to do all that by hand. Scripts are good
> at that kind of thing.
>
[Devin Teske]
And the installer is scriptable.
Try executing the following command to see how it can be scripted...
awk '/GLOB/{exit}/CONFIG/,/GLOB/&&/^[A-Z]+=/{print}' \
/usr/libexec/bsdinstall/scripts/zfsboot | less
>
> If the installer boot loader creates a RAM disk, copies the installer
> suite to there, and then lights it off, I might be able to choose Shell
> early on, edit the right script, and then re-launch the installer.
>
[Devin Teske]
Yes, or create a /etc/installerconfig that sets ZFSBOOT_* variables
before kicking off "bsdinstall zfsboot" (and later the distextract, etc.).
HINT: If /etc/installerconfig exits with failure status, nothing else is
performed before reboot (allowing you to control the install 100% by
calling the various parts to the installation).
--
Devin
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