Subject: Re: raid-1 data offset
To: Greg Oster <>
From: Wojciech Puchar <>
List: netbsd-users
Date: 08/06/2001 21:38:16
> Wojciech Puchar writes:
> > what is an offset (in sectors) between beginning of partition used to make
> > raid and raid data stored on it
> 64 sectors.

thank you

> > as bootblock in 1.5.1 doesn't support RAID-1 boot
> Hmmm... It's supposed to.. (It knows to look for a FS_RAID partition)

in 1.5.1? at least no info in man boot but grep -i raid found 1 line in

> The bigger problem is that installboot doesn't know how to deal with
> RAID partitions.

no problem - i will create 100kB partition just for bootloader.

> > i would like to make
> > "shadow" partition just for them like that on both disks:
> >
> > a: <raidsize> <e_begin+offset> 4.2BSD ....
> > ..
> > ..
> > ..
> > e: <raidsize> <e_begin> RAID .....
> > f: 200       somewhere 4.2BSD
> >
> > and install bootblocks (nothing else) on f, which then will boot from a
> > not knowing that it's on RAID-1
> This should work, but be *VERY* careful that you don't get the RAID components
> inconsistent by modifying any data in the 'a' components without going
> through the RAID set.  If you must modify the data on 'a' directly (without

i will never use a partition of disk only /dev/raid0a or rraid0a

> going through RAID), then first use 'raidctl -f wd1e' (or whatever) to fail
> the mirror part of the RAID set.  Once you're done mucking with 'a', then you
> can use 'raidctl -R wd1e' and sync the arrays up again.  If you don't do the
> 'raidctl -f' and then you change data on 'a', there is a very good chance that
> you'll end up with serious filesystem corruption... but if you're careful, it
> should work..
> Later...
> Greg Oster