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Date:      Fri, 25 Sep 2009 14:49:14 -0700
From:      Artem Belevich <fbsdlist@src.cx>
To:        Stefan Bethke <stb@lassitu.de>
Cc:        Ollivier Robert <roberto@keltia.freenix.fr>, dfr@freebsd.org, freebsd-current@freebsd.org
Subject:   Re: Booting off raidz *mostly* work
Message-ID:  <ed91d4a80909251449i47d2a31dw4ebfd74f71e29dba@mail.gmail.com>
In-Reply-To: <AE91C53E-FD74-4B6D-9498-D4F11FE5AA2E@lassitu.de>
References:  <20090925154125.GD48707@roberto-al.eurocontrol.fr> <AE91C53E-FD74-4B6D-9498-D4F11FE5AA2E@lassitu.de>

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Our bootloader implementation does not know how to read gang blocks.
Compare the code from OpenSolaris' variant of grub with what we have
and find the differences:

Search for zio_read_data here:
http://bitbucket.org/osunix/osunix-gate/src/1cca4617b3a8/usr/src/grub/grub-=
0.97/stage2/fsys_zfs.c

And compare with our zio_read here:
http://fxr.watson.org/fxr/source/boot/zfs/zfsimpl.c?im=3Dexcerpts#L900

We seem to be missing gang block check. That would explain why zfsboot
works only sometimes. If all the files are written using regular
blocks, then we're OK. However, some time later (i.e. during upgrade
or after an edit), some data can end up written to disk in a gang
block and that would make zfsboot choke.

--Artem



On Fri, Sep 25, 2009 at 1:57 PM, Stefan Bethke <stb@lassitu.de> wrote:
> Am 25.09.2009 um 17:41 schrieb Ollivier Robert:
>
>> According to Ollivier Robert:
>>>
>>> By popular demand:
>>> http://www.keltia.net/howtos/zfsboot
>>
>> I've succeeded in booting off raidz!
>>
>> There is a remaining issue with /boot/loader getting zfs errors at boot
>> time
>> resulting in loader.conf not being read. After setting the various
>> variables
>> manually (vm.kmem_size, vfs.root.mountfrom) and loading zfs, it works...
>>
>> http://static.keltia.net/download/raidz-boot.png
>>
>> I've updated the howto to reflect that.
>>
>> Any help in tackling the last issue is welcome.
>
> In my various experiments, I sometimes got a setup that would load many, =
but
> not all files. =A0However, re-running the script to re-create the zpool, =
or
> copying files to the filesystem would make any successive reboots not wor=
k
> anymore.
>
>
> Stefan
>
> --
> Stefan Bethke <stb@lassitu.de> =A0 Fon +49 151 14070811
>
>
>
>
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