====== fdisk ======

  * [[Filesystems]]
  * [[NetBSD]]
  * [[OpenBSD]]
  * [[disklabel]]
  * [[newfs]]
  * [[raidctl]]
  * [[softraid]]
  * [[sysctl]]

  * [[http://www.daemonforums.org/showthread.php?t=2824|HOWTO: reformat a USB flash drive in NetBSD]]
==== Linux and NetBSD Partitioning ====

Partitioning drives in NetBSD is different than Linux.  In Linux, there is one MBR table with partitions for as many filesystems as you would like.

In NetBSD, one partition is created from the original four that are found with an MBR table, then disklabel is used to create it's own form of partitions called slices within the MBR partition.

In other words, running ''fdisk'' in Linux on a hard drive with NetBSD installed, would show only one partition created.

=== netbsd-vm Example ===

== Linux ==

The drives here are IDE drives, so they show up as ''wdX'' instead of ''sdX'' in NetBSD.

Here's what ''fdisk -l /dev/sda'' would return in Linux, for the MBR partitions:

<code>
Disk /dev/sda: 12.9 GB, 12884901888 bytes, 25165824 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048    25165823    12581888   a9  NetBSD
</code>

== NetBSD ==

''fdisk wd0'' will also show the MBR partitions:

<code>
Disk: /dev/rwd0d
NetBSD disklabel disk geometry:
cylinders: 24966, heads: 16, sectors/track: 63 (1008 sectors/cylinder)
total sectors: 25165824

BIOS disk geometry:
cylinders: 1024, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
total sectors: 25165824

Partitions aligned to 2048 sector boundaries, offset 2048

Partition table:
0: NetBSD (sysid 169)
    start 2048, size 25163776 (12287 MB, Cyls 0-1566/127/33), Active
1: <UNUSED>
2: <UNUSED>
3: <UNUSED>
Bootselector disabled.
First active partition: 0
</code>
==== Format a NetBSD Hard Drive ====

There are a lot of different device names for the same thing, so to keep things simple, just use ''sd0'', ''sd1'', etc. for the MBR partitions.

Display status of a disk:

<code>
fdisk sd0
</code>

== Initialization ==

Use ''fdisk'' to create an MBR partition table (same as on Linux).

Do this before disklabel or newfs:

<code>
fdisk -u sd0
</code>

<code>
fdisk: primary partition table invalid, no magic in sector 0
Disk: /dev/sd1
NetBSD disklabel disk geometry:
cylinders: 224, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
total sectors: 3604865

BIOS disk geometry:
cylinders: 1023, heads: 255, sectors/track: 63 (16065 sectors/cylinder)
total sectors: 1952448512

Partitions aligned to 16065 sector boundaries, offset 63

Do you want to change our idea of what BIOS thinks? [n] n

Partition table:
0: <UNUSED>
1: <UNUSED>
2: <UNUSED>
3: <UNUSED>
Bootselector disabled.
No active partition.
Which partition do you want to change?: [none] 0
The data for partition 0 is:
<UNUSED>
sysid: [0..255 default: 169] 
start: [0..224cyl default: 63, 0cyl, 0MB] 
size: [0..224cyl default: 3604802, 224cyl, 1760MB] 
bootmenu: [] 

Partition table:
0: NetBSD (sysid 169)
    start 63, size 3604802 (1760 MB, Cyls 0-224/100/5)
        PBR is not bootable: All bytes are identical (0x00)
1: <UNUSED>
2: <UNUSED>
3: <UNUSED>
Bootselector disabled.
No active partition.
Which partition do you want to change?: [none] 

We haven't written the MBR back to disk yet.  This is your last chance.
Partition table:
0: NetBSD (sysid 169)
    start 63, size 3604802 (1760 MB, Cyls 0-224/100/5)
        PBR is not bootable: All bytes are identical (0x00)
1: <UNUSED>
2: <UNUSED>
3: <UNUSED>
Bootselector disabled.
No active partition.
Should we write new partition table? [n] y
</code>

== Partition hard drive ==

Edit the NetBSD partitions (slices):

<code>
disklabel -i -I sd1
</code>

<code>
Enter '?' for help
partition> d
Filesystem type [?] [4.2BSD]: 4.2BSD
Start offset ('x' to start after partition 'x') [0c, 0s, 0M]: 
Partition size ('$' for all remaining) [953344c, 1952448512s, 953344M]: $
partition> W
Label disk [n]? y
Label written
partition> Q
</code>