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2. The FreeBSD way of labelling hard drives

Linux and FreeBSD label hard drives and partitions after two differents schemes. This section explains the main differences between the two schemes.

2.1 FreeBSD ``slices'' and ``partitions''

FreeBSD needs only one entry in the primary partition table on your hard drive. This primary partition is called a ``slice'' in FreeBSD terminology. It then uses the program disklabel to make several logical partitions in this primary partition. These logical partitions are called ``partitions'' in FreeBSD terminology. This concept is similar to the way Linux (and DOS) handles logical partitions in an extended partition. Note that the Linux fdisk program can't display the partitions in a FreeBSD slice, the output is something like this (/dev/hda4 is the FreeBSD slice):

hafnium:~# fdisk /dev/hda

Command (m for help): p

Disk /dev/hda: 64 heads, 63 sectors, 621 cylinders
Units = cylinders of 4032 * 512 bytes

   Device Boot   Begin    Start      End   Blocks   Id  System
/dev/hda1   *        1        1       27    54400+  83  Linux native
/dev/hda2           28       28      375   701568   83  Linux native
/dev/hda3          376      376      403    56448   83  Linux native
/dev/hda4          404      404      621   439488   a5  BSD/386

Command (m for help): q
hafnium:~#

2.2 Drive and partition labelling in Linux and FreeBSD

The hard drives are labelled in the following way in Linux and FreeBSD:

                        Linux           FreeBSD
First IDE drive         /dev/hda        /dev/wd0
Second IDE drive        /dev/hdb        /dev/wd1
First SCSI drive        /dev/sda        /dev/sd0
Second SCSI drive       /dev/sdb        /dev/sd1

The partitions (FreeBSD slices) on a drive are labelled in the following way (/dev/hda is used as an example):

                                Linux           FreeBSD
First primary partition         /dev/hda1       /dev/wd0s1
Second primary partition        /dev/hda2       /dev/wd0s2
Third primary partition         /dev/hda3       /dev/wd0s3
Fourth primary partition        /dev/hda4       /dev/wd0s4

The partitions in a FreeBSD slice is labelled in the following way (/dev/hda4 is the FreeBSD slice in the example):

Linux label     FreeBSD label   Default FreeBSD mount point 
/dev/hda5       /dev/wd0s4a     /
/dev/hda6       /dev/wd0s4b     swap
/dev/hda7       /dev/wd0s4e     /var
/dev/hda8       /dev/wd0s4f     /usr

If you have installed FreeBSD in the /dev/sdb3 slice, and /dev/sdb2 is a Linux extended partition containing two logical partitions (/dev/sdb5 and /dev/sdb6), the previous example would look like this:

Linux label     FreeBSD label   Default FreeBSD mount point 
/dev/sdb7       /dev/sd1s3a     /
/dev/sdb8       /dev/sd1s3b     swap
/dev/sdb9       /dev/sd1s3e     /var
/dev/sdb10      /dev/sd1s3f     /usr


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