ZFS boot on zfs mirror

Lorenzo Perone lopez.on.the.lists at yellowspace.net
Tue May 26 12:20:31 UTC 2009

Hi All,

Thanx for all the feedback!

Philipp: Your idea is really fine, with manageBE :)
Would surely be nice for a test/development machine,
I'll think about using it... (sounds a bit like
FreeBSD goin' the Nexenta way...)

Mickael: Your example looks much more like what I was
looking  for (and thank god UNIX still is mostly
ASCII so I can follow the link You posted).

But, just as a side question: how much of a risk of
creating an [ugly] race condition is it actually,
to use swap on a zvol?

Yet another question would be, how much is performance
impacted by the zfs overhead (ok, leaving aside that
a swapping system needs ram - wherever the swap is located...)?
But hey, snapshotting swap - isn't THAT funky? ;)

Thanx to all for the feedback, it's great to
be a FreeBSD user all the time!

I'll be trying to set this up ASAP.



On 26.05.2009, at 11:26, Mickael MAILLOT wrote:

> Hi,
> i prefere use zfsboot boot sector, an example is better than a long  
> talk:
> $ zpool create tank mirror ad4 ad6
> $ zpool export tank
> $ dd if=/boot/zfsboot of=/dev/ad4 bs=512 count=1
> $ dd if=/boot/zfsboot of=/dev/ad6 bs=512 count=1
> $ dd if=/boot/zfsboot of=/dev/ad4 bs=512 skeep=1  seek=1024
> $ dd if=/boot/zfsboot of=/dev/ad6 bs=512 skeep=1  seek=1024
> $ zpool import tank
> $ zpool set bootfs=tank tank
> $ zfs set mountpoint=legacy tank
> add vfs.root.mountfrom="zfs:tank" to your loader.conf
> now you can boot on ad4 or ad6
> Source:
> http://www.waishi.jp/~yosimoto/diary/?date=20080909
> 2009/5/25 Philipp Wuensche <cryx-freebsd at h3q.com>:
>> Lorenzo Perone wrote:
>>> Hello to all,
>>> Having licked blood now, and read the news from Kip Macy about
>>>> -  zfs boot for all types now works
>>> I was wondering if anyone has some updated tutorial on how to  
>>> achieve a
>>> zfs-only bootable FreeBSD with a mirrored zpool.
>> My own howto and script to do the stuff automated:
>> http://outpost.h3q.com/patches/manageBE/create-FreeBSD-ZFS-bootfs.txt
>> But beware, it is meant to use with
>> http://anonsvn.h3q.com/projects/freebsd-patches/wiki/manageBE
>> afterwards. But the steps are the same.
>>> Searching around I found this tutorial on how to set up a ZFS  
>>> bootable
>>> system, which is mostly straightforward:
>>> http://blogs.freebsdish.org/lulf/2008/12/16/setting-up-a-zfs-only-system/
>>> However it leaves a few questions open... How am I supposed to  
>>> make a
>>> zfs mirror out of it? Suppose I have ad4 and ad6, should I repeat  
>>> the
>>> exact same gpart-steps for both ad4 and ad6, and then make a zpool
>>> create data mirror ad4p3 ad6p3?
>> Exactly.
>>> How about swap? I suppose it will be on
>>> one of the disks?
>> I keep swap in a seperate partition. You could either use two swap
>> partition, each on one disk or use gmirror to mirror a single swap
>> partition to be safe from disk crash.
>>> And what if I start with one disk and add the second
>>> one later with zpool attach?
>> This will work. Just do the same gpart commands on the second disk  
>> and
>> use zpool attach.
>> greetings,
>> philipp
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