Re: boot disk has two MBR partitions

[eric%cirr.com@localhost (Eric Schnoebelen)]

"=?utf-8?Q?Saifi=20Khan?=" writes:
- Now, i have a boot disk (NetBSD terminology) of 320 GB (SATA II). 
- 
- Booted my laptop with 'boot.iso' (NetBSD-current) and using the
- 'NetBSD' fdisk utility, i created two MBR partitions (NetBSD
- terminology) of the following size:
- 
-  partition no 1: 20 GB   (base system, src)
-  partition no 2: 300 GB (pkgsrc, other sources, mails etc.)
- 
- i intend to setup 'ffs' on both the MBR partitions.
- 
- in the linux world, the disk would typically be '/dev/sda' and the
- two profound partitions would be
- 
-  /dev/sda1
-  /dev/sda2
- 
- in the NetBSD scheme of things, the first disk is seen as 'wd0'.
- In that case, how would the two 'MBR partitions' be addressed as?

NetBSD doesn't use MBR partitions to define individual
filesystems.  In NetBSD (and nearly every other UNIX-like
operating system on the x86 besides Linux) uses one MBR
partition to contain all of its filesystems.

So, for the above partitioning scheme, you want a single NetBSD
partion of 320Gb, and then two BSD partitions (or slices)
defined using disklabel(8).  More than likely they will be wd0a and
wd0e once you've completed labeling.

- i also have a couple of related questions:
- 
- 1. what is the rationale behind using 'd' in BSD partition to
-    represent the entire disk ?

Traditionally, 'c' was the entire disk of a diskpack on BSD
systems (such as VAXen, Alpha, HPs, etc.).  Early in the history
of BSD on i386, it was decided that 'c' should reference the BSD
MBR partition.  Somewhere along the line, it was realized that
access to the entire disk, including non-BSD MBR partitions
would be useful, so 'd' was choosen for that purpose on the
i386, and carried over to the x86_64/amd64.  On other
platoforms, 'd' can be used as a regular partition.

- 2. what is the significance of using two representations like wd0 and rwd0?

One is the raw (unbuffered) device, treated as a character
access device, while the other is the block addressed/access
device. rwd0 is the raw device, and wd0 is the block addressed
(and buffered) device.

- 3. does fsck like utility perform better when one has slice with
-    BSD partitions rather than straight DOS like partition ?

I'm not following what is being asked here..

--
Eric Schnoebelen                eric%cirr.com@localhost                 
http://www.cirr.com
``...if a design for a teleporter ends up creating a miniature black hole
  in your machine room, well, hey, sometimes that kind of thing happens
  when you're tweaking reality using open source tools.'' -- Benjy Feen