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Re: offset 63 or 0 for disklabel/fdisk?



In RAID(4) you can read:

> In all cases the `raw' partitions of the disks must not
> be combined. Rather, each component partition should be
> offset by at least one cylinder from the beginning of that
> component disk. This ensures that the disklabels for the
> component disks do not conflict with the disklabel for the
> raid device. As well, all component partitions must be of
> the type FS_BSDFFS.
>

I have a disk which I initialized with fdisk -i and labeled with disklabel.
Can I use /dev/sd1e as component of a RAID or do I have to change the
partition with fdisk to start at Cylinder 1 instead of 0?


# fdisk sd1
Disk: sd1       geometry: 263/255/63 [4225095 sectors]
Offset: 0       Signatures: 0xAA55,0x0
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 0: 00    0   0   0 -    0   0   0 [         0 -          0] unused
 1: 00    0   0   0 -    0   0   0 [         0 -          0] unused
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused
*3: A6    0   1   1 -  262 254  63 [        63 -    4225032] OpenBSD

# disklabel sd1
# using MBR partition 3: type A6 off 63 (0x3f) size 4225032 (0x407808)
# /dev/rsd1c:
type: SCSI
disk: SCSI disk
label: DCAS-32160W
flags:
bytes/sector: 512
sectors/track: 172
tracks/cylinder: 3
sectors/cylinder: 516
cylinders: 8188
total sectors: 4226725
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # microseconds
track-to-track seek: 0  # microseconds
drivedata: 0

16 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:   204789       63    4.2BSD     1024  8192    16   # (Cyl.    0*- 396)
  b:   614556   204852      swap                        # (Cyl.  397 - 1587)

  c:  4226725        0    unused        0     0         # (Cyl.    0 -
8191*)
  e:  3407317   819408    4.2BSD     1024  8192    16   # (Cyl. 1588 -
8191*)
#




Sven


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