ZFS booting without partitions (was: ZFS boot on zfs mirror)

[Lorenzo Perone]

Hi,

I tried hard... but without success ;(

the result is, when choosing the disk with the zfs boot
sectors in it (in my case F5, which goes to ad6), the kernel
is not found. the console shows:

forth not found
definitions not found
only not found
(the above repeated several times)

can't load 'kernel'

and I get thrown to the loader prompt.
lsdev does not show any ZFS devices.

Strange thing: if I boot from the other disk, F1, which is my
ad4 containing the normal ufs system I used to make up the other
one, and escape to the loader prompt, lsdev actually sees the
zpool which is on the other disk, and shows:
zfs0: tank

I tried booting with boot zfs:tank or zfs:tank:/boot/kernel/kernel,
but there I get the panic: free: guard1 fail message.
(would boot zfs:tank:/boot/kernel/kernel be correct, anyways?)

Sure I'm doing something wrong, but what...? Is it a problem that
the pool is made out of the second disk only (ad6)?

Here are my details (note: latest stable and biosdisk.c merged
with changes shown in r185095. no problems in buildworld/kernel):

<snip>

Machine: p4 4GHz 4 GB RAM (i386)

Note: the pool has actually a different name (heidi
instead of tank, if this can be of any relevance...),
just using tank here as it's one of the conventions...

mount (just to show my starting situation)

/dev/mirror/gm0s1a on / (ufs, local)
devfs on /dev (devfs, local)
/dev/mirror/gm0s1e on /tmp (ufs, local, soft-updates)
/dev/mirror/gm0s1f on /usr (ufs, local, soft-updates)
/dev/mirror/gm0s1d on /var (ufs, local, soft-updates)

gmirror status
       Name    Status  Components
mirror/gm0  DEGRADED  ad4
(ad6 used to be the second disk...)

echo 'LOADER_ZFS_SUPPORT=yes' >> /etc/make.conf

cd /usr/src
make buildworld && make buildkernel KERNCONF=HEIDI
make installkernel KERNCONF=HEIDI
mergemaster
make installworld
shutdown -r now

dd if=/dev/zero of=/dev/ad6 bs=512 count=32

zpool create tank ad6
zfs create tank/usr
zfs create tank/var
zfs create -V 4gb tank/swap
zfs set org.freebsd:swap=on tank/swap
zpool set bootfs=tank tank

rsync -avx / /tank
rsync -avx /usr/ /tank/usr
rsync -avx /var/ /tank/var
cd /usr/src
make installkernel KERNCONF=HEIDI DESTDIR=/tank

zpool export tank

dd if=/boot/zfsboot of=/dev/ad6 bs=512 count=1
dd if=/boot/zfsboot of=/dev/ad6 bs=512 skip=1 seek=1024

zpool import tank

zfs set mountpoint=legacy tank
zfs set mountpoint=/usr tank/usr
zfs set mountpoint=/var tank/var

shutdown -r now ...

at the 'mbr prompt' I pressed F5 (the second disk, ad6)
.. as written above, loader gets loaded (at this stage
I suppose it's the stuff dd't after block 1024?),
but kernel not found.

/usr/src/sys/i386/conf/HEIDI:
(among other things...):
options KVA_PAGES=512

(/tank)/boot/loader.conf:
vm.kmem_size="1024M"
vm.kmem_size_max="1024M"
vfs.zfs.arc_max="128M"
vfs.zfs.vdev.cache.size="8M"
vfs.root.mountfrom="zfs:tank"

(/tank)/etc/fstab:
# Device		Mountpoint	FStype	Options		Dump	Pass#
tank		/		zfs	rw		0	0
/dev/acd0		/cdrom		cd9660	ro,noauto	0	0

</snap>

any help is welcome... don't know where to go from here right now.

BTW: I can't stop thanking the team for the incredible
pace at which bugs are fixed these days!


Regards,

Lorenzo



On 26.05.2009, at 18:42, George Hartzell wrote:

> Andriy Gapon writes:
>> on 26/05/2009 19:21 George Hartzell said the following:
>>> Dmitry Morozovsky writes:
>>>> On Tue, 26 May 2009, Mickael MAILLOT wrote:
>>>>
>>>> MM> Hi,
>>>> MM>
>>>> MM> i prefere use zfsboot boot sector, an example is better than  
>>>> a long talk:
>>>> MM>
>>>> MM> $ zpool create tank mirror ad4 ad6
>>>> MM> $ zpool export tank
>>>> MM> $ dd if=/boot/zfsboot of=/dev/ad4 bs=512 count=1
>>>> MM> $ dd if=/boot/zfsboot of=/dev/ad6 bs=512 count=1
>>>> MM> $ dd if=/boot/zfsboot of=/dev/ad4 bs=512 skeep=1  seek=1024
>>>> MM> $ dd if=/boot/zfsboot of=/dev/ad6 bs=512 skeep=1  seek=1024
>>>>
>>>> s/skeep/skip/ ? ;-)
>>>
>>> What is the reason for copying zfsboot one bit at a time, as opposed
>>> to
>>>
>>>  dd if=/boot/zfsboot of=/dev/ad4 bs=512 count=2
>>
>> seek=1024 for the second part? and no 'count=1' for it? :-)
>>
>> [Just guessing] Apparently the first block of zfsboot is some form  
>> of MBR and the
>> rest is zfs-specific code that goes to magical sector 1024.
>
> Ok, I managed to read the argument to seek as "one block", apparently
> my coffee hasn't hit yet.
>
> I'm still confused about the two parts of zfsboot and what's magical
> about seeking to 1024.
>
> g.
>
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