Congratulations! Thanks for sharing, I'm guessing that you've
probably prevented a few ppl from tripping on this by posting this.
Me; I'm still waiting for:
make zfs ad0s1, ad1s1, ad2s1 install. :-)

Best wishes.

--Chris

Quoting Bartosz Stec <[EMAIL PROTECTED]>:

Hello there!
Here's my story, hopefully some of you won't follow my steps and
avoid some troubles :)

Yesterday I've decided that's about time to test zfs functionality on
my home server PC (i386 FreeBSD 7.1-pre) . A couple of weeks ago I
bought new desktop PC (with SATA), so I had a bunch of PATA disks
from old one to use in server. Lucky me - there was 3 HDD at size
40GB - RAIDZ was on approch!

So after a thirty minutes I had a plan, and my server had 4 disks
connected - one 20GB with actual system (ad1), and three 40GB to
replace actual system (ad[023]).
Plan was simple:

   1. csup freebsd-stable
   2. follow the tuning guide for zfs, rebuild world, kernel, and
   follow system upgrade
   3. Reboot in single user mode
   4. fdisk new disks with sysinstall using one big slice for every disk
   5. bsdlabel every new disk with sysinstall using: 1GB for /, 512MB
   for swap, and rest unused (for ZFS)
   6. gmirror -n -v -b round-robin boot ad0s1a ad2s1a ad3s1a
   7. newfs /dev/mirror/boot
   8. mount /dev/mirror/boot /mnt && cd /mnt
   9. dump -h 0 -L -f - -C 32 / | restore rf -
   10. zpool create tank raidz ad0s1d ad2s1d ad3s1d
   11. zfs create new cool filesystems :)
   12. dump | restore old ufs2 filesystem to new cool zfs filesystems :)
   13. changing mount points from tank/foo to /foo
   14. edit new fstab on mirror by replacing root mount point by "boot"
   mirror, adding new swaps and remove ald ones and all fs now placed
   on zpool
   15. power off system, detach ad1 and power on new system in mixed
   gmirror - raidz environment. Yay!

Well...it has almost works. Sysinstall screw it up. I was always too
lazy to read man bsdlabel, that's why I've been using this "nice"
tool for disk related tasks. Such a mistake!
Problem with labels created with sysinstal, is that it aks for a
mount point for every partition in slice. Well, in my case it was
unwanted behaviour, so on every disk I created first:

   a:    /     b:   swap
   c:   none
   d:  /foo

Then by using "M" key I removed mount points and saved changes with
"W". At this point everything seems ok. So I've added gmirror to
loader.conf and run "gmirror label -n -v -b round-robin boot ad0s1a
ad2s1a ad3s1a". Still ok until now. Next step - kldload geom_mirror.
Here's disaster! System became unresponsible and hangs after a while.
Reboot didn't help, just after gmirror module was loaded by kernel,
screen was flooded with messages:

   WARNING: Expected rawoffset 0, found 63

andy didn't boot. I've made system start only because an old drive
ad1 has no gmirror module added to loader.conf. So after reboot I've
cleared metadata on providers and made some another attempts, but
results were always the same. Finally I have found explanation for
this issue. Man bsdlabel says:

   /offset/  The offset of the start of the partition from the beginning of
             the drive in sectors, or *** to have *bsdlabel* calculate
the correct
             offset to use (the end of the previous partition plus one, ignor-
             ing partition `c').  For partition `c', *** will be interpreted as
             an offset of 0.  The first partition should start at offset 16,
             because the first 16 sectors are reserved for metadata.


So proper labels for disks should be (and they are now):

   # /dev/ad0s1:
   8 partitions:
   #        size   offset    fstype   [fsize bsize bps/cpg]
     a:  2097152       16    4.2BSD        0     0     0
     b:  1048576  2097168      swap
     c: 78156162        0    unused        0     0         # "raw"
   part, don't edit
     d: 75010418  3145744    unused        0     0

Problem was - Sysinstall has placed partition "a:" starting with
offset 0! This is what happens when you don't RTFM :) I assume that
this bug occured because I created mount point for root on ad[023]s1a
and removed it after, than saved label. It seems that GEOM framework
didn't expect this, neither maual for bsdlabel. I think that should
be fixed somehow.
Fortunately manually editing labels by "bsdlabel -e" wasn't so hard
as I expected. This is how I made everything back to normal:

     a:  1024M       *    4.2BSD        0     0     0
     b:  512M  *      swap
     c: 78156162        0    unused        0     0         # "raw"
   part, don't edit
     d:     *      *    unused        0     0

After that, gmirror has stopped pissing me off, and I finished my
plan, as below:

   # zpool status
     pool: tank
    state: ONLINE
    scrub: scrub completed with 0 errors on Wed Sep  3 10:10:07 2008
   config:

           NAME        STATE     READ WRITE CKSUM
           tank        ONLINE       0     0     0
             raidz1    ONLINE       0     0     0
               ad0s1d  ONLINE       0     0     0
               ad2s1d  ONLINE       0     0     0
               ad3s1d  ONLINE       0     0     0

   errors: No known data errors

   # gmirror status
          Name    Status  Components
   mirror/boot  COMPLETE  ad0s1a
                          ad2s1a
                          ad3s1a

Good luck with ZFS everyone! :) And RTFM ;)

--
Bartosz Stec - specjalista ds. IT

AUXILIA Spółka z o.o.


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