geom mirror

[Josef Karthauser]

On Sat, Mar 26, 2005 at 12:48:35PM +0000, Josef Karthauser wrote:
> I'm trying to get a geom mirror up and running on a remote server across
> two ide drives using the recipe below.    I get as far as booting onto
> the second ide drive using 
> 
>     1:ad(1,a)/boot/loader
> 
> at the boot block.  The boot block complains that ad1 doesn't contain a
> valid label however and refuses to boot.
> 
> There appears to be a valid label on the gm0 device:
> 
>     jonah# disklabel mirror/gm0s1
>     # /dev/mirror/gm0s1:
>     8 partitions:
>     #        size   offset    fstype   [fsize bsize bps/cpg]
>       a:  2097152        0    4.2BSD     2048 16384 28552 
>       b:  6291456  2097152      swap                    
>       c: 240121664        0    unused        0     0         # "raw" part,
>     don't edit
>       d: 41943040  8388608    4.2BSD     2048 16384 28552 
>       e: 41943040 50331648    4.2BSD     2048 16384 28552 
>       f: 20971520 92274688    4.2BSD     2048 16384 28552 
>       g: 84932416 113246208    4.2BSD     2048 16384 28552 
>       h: 41943040 198178624    4.2BSD     2048 16384 28552 
> 
> and there does appear to be an error on the ad1s1:
> 
>     jonah# disklabel ad1s1
>     # /dev/ad1s1:
>     8 partitions:
>     #        size   offset    fstype   [fsize bsize bps/cpg]
>       a:  2097152        0    4.2BSD     2048 16384 28552 
>       b:  6291456  2097152      swap                    
>       c: 240121664        0    unused        0     0         # "raw" part,
>     don't edit
>       d: 41943040  8388608    4.2BSD     2048 16384 28552 
>       e: 41943040 50331648    4.2BSD     2048 16384 28552 
>       f: 20971520 92274688    4.2BSD     2048 16384 28552 
>       g: 84932416 113246208    4.2BSD     2048 16384 28552 
>       h: 41943040 198178624    4.2BSD     2048 16384 28552 
>     disklabel: partition c doesn't cover the whole unit!
>     disklabel: An incorrect partition c may cause problems for standard
>     system utilities
> 
> Is this to be expected?  What have I done wrong?
> 

Just replying to myself here.

What is the relationship between geom mirror partitions and native ones,
i.e. ad1s1 vs mirror/gm0s1?  The disk labels above look spookily
similar, but I didn't set a disklabel on ad1s1 manually.

With respect to booting do the first stage boot blocks know anything
about gmirror partitions?  How is the linkage between native devices and
gmirror devices done at boot time?

Joe

p.s. 

My fdisk reports:

    jonah# fdisk ad1
    ******* Working on device /dev/ad1 *******
    parameters extracted from in-core disklabel are:
    cylinders=238216 heads=16 sectors/track=63 (1008 blks/cyl)

    Figures below won't work with BIOS for partitions not in cyl 1
    parameters to be used for BIOS calculations are:
    cylinders=238216 heads=16 sectors/track=63 (1008 blks/cyl)

    Media sector size is 512
    Warning: BIOS sector numbering starts with sector 1
    Information from DOS bootblock is:
    The data for partition 1 is:
    sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
	start 63, size 240121665 (117246 Meg), flag 80 (active)
	    beg: cyl 0/ head 1/ sector 1;
	    end: cyl 647/ head 15/ sector 63
    The data for partition 2 is:
    <UNUSED>
    The data for partition 3 is:
    <UNUSED>
    The data for partition 4 is:
    <UNUSED>





-- 
Josef Karthauser (joe at tao.org.uk)	       http://www.josef-k.net/
FreeBSD (cvs meister, admin and hacker)     http://www.uk.FreeBSD.org/
Physics Particle Theory (student)   http://www.pact.cpes.sussex.ac.uk/
================ An eclectic mix of fact and theory. =================
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