[rescue] RPi vs SS20 benchmarks (interesting)

Peter Corlett abuse at cabal.org.uk
Wed Dec 30 17:54:53 CST 2015

On Wed, Dec 30, 2015 at 09:05:53AM -0700, patrick at zill.net wrote:
> Yes, before 10 it was a pain to have boot on root. Can you now do a full ZFS
> install with nothing else needed?

Yes. I eschewed the automated installer because I didn't care for its choice
of partition layout and ZFS filesystems (thanks, but I don't need a gaggle
of filesystems along the lines of /usr/src/ and /opt/var/wtf/ cluttering up
df output) so I got to learn how to install it all the hard way and discover
the bugs in the otherwise outstanding documentation.

In case anybody wants the free lesson:

The GPT partition table is 17kiB and partitions are normally 1MiB-aligned,
wasting a whole 1007kiB of at the start of the disk that offends my sense of
elegance even if the box does have 8TB in it. (Why, that's 1007kiB wasted
*per disk!) FreeBSD requires a tiny partition for the second-stage
bootloader, so it's tempting to stick it in that space. Just don't make it
1007kiB as it's loaded into the 8086 address space and won't fit. Just make
it 64kiB and perhaps you can cram DOS into the remaining unloved 943kiB.

The second-stage bootloader doesn't understand all of the fancy new ZFS
options, and gives an error message that will mislead you. Make sure the
filesystem containing /boot has conservative settings of recordsize=128k,
compression=off or lz4, and probably dedup=off.

If you want to use GELI encryption, you'll need a separate unencrypted /boot
partition. If you have a HP Microserver with convenient-looking internal
bootable Micro-SD and USB slots and a drawer full of cast-off 512MB Micro-SD
cards and USB keys, it is tempting to marry the two. Don't be tempted,
because /boot will inevitably be exactly 1MB larger than whichever card you
picked, despite a du of /boot on an identical FreeBSD system clearly showing
there's only 237MB of data.

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