strange RF_PROTECTED_SECTORS magic

[theo borm <theo_nbusr%borm.org@localhost>]

Hi,

While configuring new raid1 array, with the intent of eventually using 
grub to boot, I bumped into something curious.
As I understood it the raidframe reserves RF_PROTECTED_SECTORS at the 
start of a raid volume. I would therefore expect that if I substract the 
size of a raid volume (raid0d) from the size of its container (sd0a), to 
get this same figure.

If I do so, I get 1953525136-1953524992=144.
As far as I know RF_PROTECTED_SECTORS=64

This does not add up. Am I missing something obvious?

To boot NetBSD from a raid1 volume using grub I should get the offsets 
right. I haven't tried to install grub and NetBSD on it because I am 
afraid that I will then spend a lot of time and just end up with a 
botched disk

Below the relevant fdisk/disklabel bits.


regards, Theo



PROMPT~-> fdisk sd0
Disk: /dev/rsd0d
NetBSD disklabel disk geometry:
cylinders: 500, heads: 8, sectors/track: 32 (256 sectors/cylinder)
total sectors: 1953525168

BIOS disk geometry:
cylinders: 500, heads: 8, sectors/track: 32 (256 sectors/cylinder)
total sectors: 1953525168

Partition table:
0: NetBSD (sysid 169)
   start 32, size 1953525136 (953870 MB, Cyls 0-7630957/5/17)
1: <UNUSED>
2: <UNUSED>
3: <UNUSED>
Bootselector disabled.



PROMPT~-> disklabel sd0
# /dev/rsd0d:
type: SCSI
disk: mydisk
label: fictitious
flags:
bytes/sector: 512
sectors/track: 32
tracks/cylinder: 8
sectors/cylinder: 256
cylinders: 500
total sectors: 1953525168
rpm: 7680
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # microseconds
track-to-track seek: 0  # microseconds
drivedata: 0

5 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
a: 1953525136        32       RAID                     # (Cyl.      0*- 
7630957*)
c: 1953525136        32     unused      0     0        # (Cyl.      0*- 
7630957*)
d: 1953525168         0     unused      0     0        # (Cyl.      0 - 
7630957*)



PROMPT~-> disklabel raid0
disklabel: Invalid signature in mbr record 0
# /dev/rraid0d:
type: RAID
disk: raid
label: fictitious
flags:
bytes/sector: 512
sectors/track: 128
tracks/cylinder: 8
sectors/cylinder: 1024
cylinders: 1907739
total sectors: 1953524992
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # microseconds
track-to-track seek: 0  # microseconds
drivedata: 0

4 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
a: 1953524992         0     4.2BSD      0     0     0  # (Cyl.      0 - 
1907739*)
d: 1953524992         0     unused      0     0        # (Cyl.      0 - 
1907739*)
disklabel: boot block size 0
disklabel: super block size 0