How to create *exactly* the same partitions in different disks

[Norberto Meijome]

Hi,
pretty simply, how do I create slices (fdisk) that are exactly the same 
throughtout different drives so they can be used in a RAID5 config?

I tried using sysinstall and typing the SAME values but they result is 
always slightly off. I tried passing the values by hand, but it changes 
it anyway.

# echo "p 2 165 20964825 467427240" | fdisk -v -f- /dev/ad6
******* Working on device /dev/ad6 *******
fdisk: WARNING: adjusting size of partition 2 from 467427240 to 467426295
    to end on a cylinder boundary
parameters extracted from in-core disklabel are:
cylinders=484521 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=484521 heads=16 sectors/track=63 (1008 blks/cyl)

Information from DOS bootblock is:
1: sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 63, size 20964321 (10236 Meg), flag 0
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 317/ head 15/ sector 63
2: sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 20964825, size 467426295 (228235 Meg), flag 0
        beg: cyl 318/ head 7/ sector 1;
        end: cyl 162/ head 15/ sector 63
3: <UNUSED>
4: <UNUSED>
fdisk: Geom not found

[root at cerberus] [Wed Aug 31 17:02:10 2005]
~
# fdisk -s /dev/ad4
/dev/ad4: 484521 cyl 16 hd 63 sec
Part        Start        Size Type Flags
   1:          63    20964762 0xa5 0x80
   2:    20964825   467427240 0xa5 0x00

[root at cerberus] [Wed Aug 31 17:01:35 2005]
~
# fdisk -s /dev/ad6
/dev/ad6: 484521 cyl 16 hd 63 sec
Part        Start        Size Type Flags
   1:          63    20964321 0xa5 0x00
   2:    20964825   467426295 0xa5 0x00


Help!!!

thanks in advance,
beto