[afnog] FreeBSD mirroring

[Antonio Godinho]

Thanks guys, I will try this and give feedback. The server is a Proliant 
ML350 G4, it does not have any hardware RAID available.

Cheers,

AG

On Thu, 27 Apr 2006 18:15:52 +0200, Phil Regnauld wrote
> On Thu, Apr 27, 2006 at 05:32:49PM +0200, Antonio Godinho wrote:
> > Hi All, 
> > 
> > I would like to mirror an already operational FreeBSD server running 
FreeBSD 
> > 6.0. I have read the instructions at 
> > http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-
mirror.html 
> > 
> > but I am not quite sure of what I will do specially when I have more than 
> > the two partitions they reccommend. I have /, swap, /usr and /var.
> 
>     Mirror the whole disk!  It doesn't matter how many partitions 
> you have.
> 
> > Has anyone done this before? I don't want to ruin the already operational 
> > installation and would like to have some additional pointers.
> 
>     Plenty :)  Got 10-15 boxes running it (plus many others running ATAPI
>     RAID/ar, ccd, vinum, raidframe -- I've tried everything :)
> 
> > The system is running on a HP server which now has two hotswap scsi disks 
> > and the FreeBSD 6.0 is running in one of them (id 0).
> 
>     Which HP server is it ?  Is it a Proliant ?  If so, they all have
>     hardware RAID...
> 
> > I don't want to find that after going through these steps the system will 
> > fail to boot.
> 
>     It's easy to do -- what I recommend is doing it via the live
>     FS CD.  Alternatively, you can do it by:
> 
>     - installing a minimal FreeBSD on the disk that will be the target
>       (blank disk)    - boot on it    - create the gmirror label on 
> the source disk (the one where all your      data is) -- the label 
> is 512 bytes written at the end of the      disk / slice / partition 
> you use:
> 
>     - change fstab on the source disk's fstab to use /dev/mirror/* devices
>     - add geom_mirror_load="YES" to the source disk's /boot/loader.conf
> 
>     - reboot from the source disk, watch it magically discover the gmirror
>       volume
>     - check everything is running, then insert the spare disk into 
> the      raid with gmirror insert
> 
>     In practice, if you have disks da0 and da1, and we have:
> 
>     da0 = source, master, good disk with data
>     da1 = destination, victim, will be overwritten by da0
> 
>     1. install FreeBSD minimal on da1 - MAKE SURE YOU DON'T ERASE 
> the other       disk!
> 
>     2. boot from da1 (by setting the boot options or moving it to the
>        first slot, whatever your machine is)
> 
>        WARNING: at this point, booting from da1 might mean that it
>        becomes da0, BE CAREFUL!
> 
>     3. check that da0 and da1 are both visible -- camcontrol devlist
> 
>     4. # gmirror label -v mymirror0 /dev/daX   (your source disk --
>        notice I don't say da0 and da1 anymore: YOU must figure out which
>        is which)
> 
>     5. # mount /dev/daXs1a /mnt
>        # vi /mnt/etc/fstab
> 
>        Replace /dev/daXs1a by /dev/mirror/mymirror0s1a where relevant
>        # vi /mnt/boot/loader.conf
>        add geom_mirror_load="YES"
> 
>        # umount /mnt
> 
>     6. Reconfigure the box so that the source disk is the boot disk
> 
>     7. boot single user, you should see near the end of the boot that
>        it has found the volume (if geom_mirror.ko loaded successfully)
> 
>     8. try mount -a, see if everything is ok
> 
>     9. insert the target disk (the one you booted from before) into
>        the raid:
> 
>        # gmirror insert mymirror0 da1
> 
>     10. That's it!  Check with gmirror status that it's rebuilding 
> in the        background.
> 
>     Note: the underlying disk is ALWAYS available -- just remove
>     geom_mirror_load from the loader.conf, reboot, boot with -a (ask 
> for    root device) and you can without problem access /dev/da0s1a 
> for example,    but then the raid is broken...
> 
>     Hope this is clear.


--
Antonio Godinho
B.Sc., MCP+I, MCSE, CCNA, CCNP
CIUEM
Maputo
Mozambique