How to safely merge two slices on harddisk?

[Rob]

Malcolm Kay wrote:
> On Tue, 10 Feb 2004 04:19, Rob wrote:
> 
>>Malcolm,
>>
>>Thank you for your detailed answer to my question.
>>
>>Malcolm Kay wrote:
>>
>>>On Mon, 9 Feb 2004 13:46, Rob wrote:
>>>    Do not change the offset of 'f'. If 'g' does not physically
>>>    follow 'f' on the disk then this is not going to work -- give up
>>>    now!!!
>>
>>How can I find that out? Is it the slice order in the disk label editor
>>from /stand/sysinstall :
> 
> 
> No! What you want is disklabel (see man page). On 5.x this seems to
> have been replaced by bsdlabel -- but I have no experience with 5.x.

The disklabel output of the disk is:

-------------------------------------------------------------------------
# disklabel /dev/ad1s1c:
[...zip...]
8 partitions:
          size   offset    fstype   [fsize bsize bps/cpg]
   c:156296322        0    unused        0     0         # (Cyl.    0 - 9728*)

   a:   204800        0    4.2BSD        0     0     0   # (Cyl.    0 - 12*)
   e:  6348800   204800    4.2BSD        0     0     0   # (Cyl.   12*- 407*)
   f:  6348800  6553600    4.2BSD        0     0     0   # (Cyl.  407*- 803*)
   g:  6348800 12902400    4.2BSD        0     0     0   # (Cyl.  803*- 1198*)
   h:   614400 19251200    4.2BSD        0     0     0   # (Cyl. 1198*- 1236*)
   b:   614400 19865600    4.2BSD     2048 16384    91   # (Cyl. 1236*- 1274*)
   d:135816322 20480000    4.2BSD        0     0     0   # (Cyl. 1274*- 9728*)
-------------------------------------------------------------------------

I have put the partitions in a new order, such that the Cyl. counts are
continuously running up. Am I right, that g physically follows f here?
If so, that would mean I can merge f and g into one new partition of 6 Gb,
right?

I actually wonder if the label editor of /stand/sysinstall can do what
I want. Since I now know that f and g are back-to-front partitions, I could
remove them and create a single new one; when I write this to disk, I can
let sysinstall also create a new filesystem on the newly merged partition.

I know this is potentially dangerous, but this way I have already
deleted the swap partition, created a new ufs partition instead and
created a file system on that; all in sysinstall.
I believe it is safe, as long as I do not run 'newfs' on the existing
partitions.

Or am I missing something important here?

Thanks,
Rob.