RBPI3B+ FreeBSD 12 ZFS

[Rodney W. Grimes]

> On Fri, 2019-02-22 at 17:38 +0200, Stefan Parvu wrote:
> > I know ZFS would need a decent amount of RAM to start with. So for
> > such low sized 
> > SBC systems, like Raspberry PI having ZFS for root might be no go.
> > 
> > What I meant was: how complicated would be right now for FreeBSD 12
> > to have an 
> > ARM64 RBPI3B+ image image which could use ZFS to boot from a SD Card.
> > 
> > Stefan Parvu
> > sparvu at kronometrix.org
> > 
> > 
> 
> People have run a 512MB beaglebone with zfs on sdcard. It surely wasn't
> high performance, and it reported needed some hand-tuning to run at
> all, but it worked.

you can run zfs based systems in a very small amount of memory,
including on FreeBSD i386 IF you limit the size of the arc
cache by
vfs.zfs.arc_max=
in /boot/loader.conf
for small memory systems I recommend no more than 50% of memory.
I have run ZFS on 128MB systems, and run a VM that is zfs root
in 1G on a daily basis.  So memory is NOT your issue with doing
this on a RPI3B+

> 
> There's a lot of mythology about sdcards and what they can and can't
> do, and how supposedly fragile they are.  It's all a bunch of noise you
> can safely ignore.  They're slow, but they're plenty reliable.

I agree.  Also you should be able to boot the RPI3B+ from USB,
and that would be a far better solution, USB can have issues
though too, but my experience is it is a slight step better than
sdcard slowness.

> -- Ian
> > > On 22 Feb 2019, at 17.23, Karl Denninger <karl at denninger.net>
> > > wrote:
> > > 
> > > On 2/22/2019 09:07, Stefan Parvu wrote:
> > > > Hi,
> > > > 
> > > > Just curious, would ZFS work on a RBPI3B+ board with 1 GB RAM
> > > > only 
> > > > using FreeBSD 12 STABLE ? the hardware is 64bit but would it boot
> > > > on
> > > > 1 GB RAM for its own ARC internal operations ?
> > > > 
> > > > Thanks,
> > > > 
> > > > Stefan Parvu
> > > > sparvu at kronometrix.org
> > > 
> > > Are you talking about attempting to mount root off a ZFS filesystem
> > > on
> > > the SD card or booting it as usual and then loading zfs once
> > > running
> > > (e.g. to talk to a USB-attached disk)?
> > > 
> > > I think you'll find that while it might run it's a very bad idea
> > > for a
> > > whole host of reasons; what purpose do you have in doing this?
> > > 
> > > -- 
> > > Karl Denninger
> > > karl at denninger.net <mailto:karl at denninger.net>
> > > /The Market Ticker/
> > > /[S/MIME encrypted email preferred]/

-- 
Rod Grimes                                                 rgrimes at freebsd.org