bsdlabel partiton c error message on new install

[Jerry McAllister]

On Fri, Oct 17, 2008 at 02:13:45PM +0200, andys wrote:

> Hi, 
> 
> on a newly installed FreeBSD 7.0 system on a dell 1950 server I see the 
> following error from bsdlabel. Is there any known issues with this or is 
> the only reasonable explanation that I have managed to mess it up without 
> even knowing? :P And should I manually change the partition c to fix the 
> prob? Is this safe to do? 
> 
> bsdlabel -A /dev/da0s1
> # /dev/da0s1:
> type: SCSI
> disk: da0s1
> label:
> flags:
> bytes/sector: 512
> sectors/track: 63
> tracks/cylinder: 255
> sectors/cylinder: 16065
> cylinders: 17750
> sectors/unit: 285155328
> rpm: 3600
> interleave: 1
> trackskew: 0
> cylinderskew: 0
> headswitch: 0           # milliseconds
> track-to-track seek: 0  # milliseconds
> drivedata: 0 
> 
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
> a: 20971520        0    4.2BSD     2048 16384 28552
> b: 20971520 75497472      swap
> c: 285153687        0    unused        0     0         # "raw" part, don't 
> edit
> d: 20971520 20971520    4.2BSD     2048 16384 28552
> e: 20971520 41943040    4.2BSD     2048 16384 28552
> f: 12582912 62914560    4.2BSD     2048 16384 28552
> bsdlabel: partition c doesn't cover the whole unit!
> bsdlabel: An incorrect partition c may cause problems for standard system 
> utilities 
> 
> thanks for any advice, Im not really confident with the FreeBSD disk 
> management as I havent used it much, 

If you were using sysinstall, I am not sure how this would come up.

Do you have more than one slice on the disk - that which MS refers
to as a 'primary partition'?   Something you might do to create a
'dual boot' machine. 

Are you in the position where you can just wipe it and do a 
reinstall?  I wouldn't just move or resize the c partition after
the fact.   

The c partition should be equal to the size of the slice it is in.
That should just be true after the fdisk part of the operation unless
there is something wrong with the size or alignment of the slice
itself.   And, in that case, I would expect it to have complained
way back in the sysinstall-fdisk part of the process.

So, I would start over if I could.

Just some pictorial perspective to make it easier (I hope) to visualize.

                           Whole device
     ____________________________________________________________
     |   slice 1    : FreeBSD Slice 2     : slice 3    : Slice 4 |
     |              :                     :            :         | 
     |              :<-   partition c   ->:            :         |
     |Some MS thing :  '    '    '    '   : Some Linux : Extra   |
     |              :pa' pb ' pd ' pe ' pn:  thing     : slice   |
     |              :  '    '    '    '   :            :         |
     |              :  '    '    '    '   :            :         |
     -------------------------------------------------------------

A device (whole disk) can have up to 4 slices labeled 1..4.   
Each slice can be of different types.   
MS calls slices 'primary partitions'.

Each FreeBSD type slice can be divided in to "8" (really 7) partitions
that are labeled a..h.   But, c must be used to define the whole slice.
Slices are created by fdisk.  Fdisk also writes the device's MBR.
Partitions are created by bsdlabel (disk label in early versions of FreeBSD)
bsdlabel also writes the slice's boot block.

It is possible to leave empty space in the whole disk that is not 
allocated to any slice or within any given slice that is not allocated
to any partition.   The total of a..h not counting c, plus any non-
allocated space, must add up to c.

It is possible to create what someone has dubbed a 'dangerously dedicated'
disk and just not create slices, but just use bsdlabel to divide the
whole disk in to FreeBSD partitions a-h.  The c partition must still
refer to the whole space available for FreeBSD partitioning.

I think it is also possible to just newfs the disk without using
either fdisk or bsdlabel and create one filesystem without slices
or partitions.    I haven't tried it.

Both fdisk and bsdlabel are supposed to keep track of the sizes
correctly, automatically.   That is why I suggest starting over.

If you use sysinstall, it calls fdisk and bsdlabel for you and you
don't have to do it separately unless you want to look and see
what it did.

////jerry

> 
> thanks Andy.
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