Although it is theoretically possible to use a full disk to house your Linux system, this is almost never done in practice. Instead, full disk block devices are split up in smaller, more manageable block devices. On Alpha systems, these are called slices.

As an example we use the following slice layout:

If you are interested in knowing how big a partition should be, or even how many partitions (or volumes) you need, read on. Otherwise continue now with Using fdisk to Partition your Disk (SRM only) or Using fdisk to Partition your Disk (ARC/AlphaBIOS only).

The number of partitions is highly dependent on your environment. For instance, if you have lots of users, you will most likely want to have your /home separate as it increases security and makes backups easier. If you are installing Gentoo to perform as a mailserver, your /var should be separate as all mails are stored inside /var. A good choice of filesystem will then maximise your performance. Gameservers will have a separate /opt as most gaming servers are installed there. The reason is similar for /home: security and backups. You will definitely want to keep /usr big: not only will it contain the majority of applications, the Portage tree alone takes around 500 Mbyte excluding the various sources that are stored in it.

As you can see, it very much depends on what you want to achieve. Separate partitions or volumes have the following advantages:

• You can choose the best performing filesystem for each partition or volume
• Your entire system cannot run out of free space if one defunct tool is continuously writing files to a partition or volume
• If necessary, file system checks are reduced in time, as multiple checks can be done in parallel (although this advantage is more with multiple disks than it is with multiple partitions)
• Security can be enhanced by mounting some partitions or volumes read-only, nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.

However, multiple partitions have one big disadvantage: if not configured properly, you might result in having a system with lots of free space on one partition and none on another.

The following parts explain how to create the example slice layout described previously, namely:

Change your slice layout according to your own preference.

To figure out what disks you have running, use the following commands:

# dmesg | grep 'drive$'        (For IDE disks)
# dmesg | grep 'scsi'          (For SCSI disks)

From this output you should be able to see what disks were detected and their respective /dev entry. In the following parts we assume that the disk is a SCSI disk on /dev/sda.

Now fire up fdisk:

# fdisk /dev/sda

If your hard drive is completely blank, then you'll have to first create a BSD disklabel.

Command (m for help): b
/dev/sda contains no disklabel.
Do you want to create a disklabel? (y/n) y
A bunch of drive-specific info will show here
3 partitions:
#       start       end      size     fstype   [fsize bsize   cpg]                                    
  c:        1      5290*     5289*    unused        0     0

We start with deleting all slices except the 'c'-slice (a requirement for using BSD disklabels). The following shows how to delete a slice (in the example we use 'a'). Repeat the process to delete all other slices (again, except the 'c'-slice).

Use p to view all existing slices. d is used to delete a slice.

BSD disklabel command (m for help): p

8 partitions:
#       start       end      size     fstype   [fsize bsize   cpg]                                    
  a:        1       235*      234*    4.2BSD     1024  8192    16
  b:      235*      469*      234*      swap
  c:        1      5290*     5289*    unused        0     0
  d:      469*     2076*     1607*    unused        0     0
  e:     2076*     3683*     1607*    unused        0     0
  f:     3683*     5290*     1607*    unused        0     0
  g:      469*     1749*     1280     4.2BSD     1024  8192    16
  h:     1749*     5290*     3541*    unused        0     0

BSD disklabel command (m for help): d
Partition (a-h): a

After repeating this process for all slices, a listing should show you something similar to this:

BSD disklabel command (m for help): p

3 partitions:
#       start       end      size     fstype   [fsize bsize   cpg]                                    
  c:        1      5290*     5289*    unused        0     0

On Alpha based systems you don't need a separate boot slice. However, the first cylinder cannot be used as the aboot image will be placed there.

We will create a swap slice starting at the third cylinder, with a total size of 1 GB. Use n to create a new slice. After creating the slice, we will change its type to 1 (one), meaning swap.

BSD disklabel command (m for help): n
Partition (a-p): a
First cylinder (1-5290, default 1): 3
Last cylinder or +size or +sizeM or +sizeK (3-5290, default 5290): +1024M

BSD disklabel command (m for help): t
Partition (a-c): a
Hex code (type L to list codes): 1

After these steps you should see a layout similar to the following:

BSD disklabel command (m for help): p

3 partitions:
#       start       end      size     fstype   [fsize bsize   cpg]                                    
  a:        3      1003      1001       swap
  c:        1      5290*     5289*    unused        0     0

We will now create the root slice, starting from the first cylinder after the swap slice. Use the p command to view where the swap slice ends. In our example, this is at 1003, making the root slice start at 1004.

Another problem is that there is currently a bug in fdisk making it think the number of available cylinders is one above the real number of cylinders. In other words, when you are asked for the last cylinder, decrease the cylinder number (in this example: 5290) with one.

When the slice is created, we change the type to 8, for ext2.

D disklabel command (m for help): n
Partition (a-p): b
First cylinder (1-5290, default 1): 1004
Last cylinder or +size or +sizeM or +sizeK (1004-5290, default 5290): 5289

BSD disklabel command (m for help): t
Partition (a-c): b
Hex code (type L to list codes): 8

Your slice layout should now be similar to this:

BSD disklabel command (m for help): p

3 partitions:
#       start       end      size     fstype   [fsize bsize   cpg]                                    
  a:        3      1003      1001       swap
  b:     1004      5289      4286       ext2
  c:        1      5290*     5289*    unused        0     0

Save fdisk by typing w. This will also save your slice layout.

Command (m for help): w

Now that your slices are created, you can continue with Creating Filesystems.

The following parts explain how to partition the disk with a layout similar to the one described previously, namely:

Change your partition layout according to your own preference.

To figure out what disks you have running, use the following commands:

# dmesg | grep 'drive$'        (For IDE disks)
# dmesg | grep 'scsi'          (For SCSI disks)

From this output you should be able to see what disks were detected and their respective /dev entry. In the following parts we assume that the disk is a SCSI disk on /dev/sda.

Now fire up fdisk:

# fdisk /dev/sda

If your hard drive is completely blank, then you'll have to first create a DOS disklabel.

Command (m for help): o
Building a new DOS disklabel.

We start with deleting all partitions. The following shows how to delete a partition (in the example we use '1'). Repeat the process to delete all other partitions.

Use p to view all existing partitions. d is used to delete a partition.

command (m for help): p

Disk /dev/sda: 9150 MB, 9150996480 bytes
64 heads, 32 sectors/track, 8727 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1         478      489456   83  Linux
/dev/sda2             479        8727     8446976    5  Extended
/dev/sda5             479        1433      977904   83  Linux Swap
/dev/sda6            1434        8727     7469040   83  Linux

command (m for help): d
Partition number (1-6): 1

On Alpha systems which use MILO to boot, we have to create a small vfat boot partition.

Command (m for help): n
Command action
  e   extended
  p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-8727, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-8727, default 8727): +16M

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 6
Changed system type of partition 1 to 6 (FAT16)

We will create a swap partition with a total size of 1 GB. Use n to create a new partition.

Command (m for help): n
Command action
  e   extended
  p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (17-8727, default 17): 17
Last cylinder or +size or +sizeM or +sizeK (17-8727, default 8727): +1000M

Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): 82
Changed system type of partition 2 to 82 (Linux swap)

After these steps you should see a layout similar to the following:

Command (m for help): p

Disk /dev/sda: 9150 MB, 9150996480 bytes
64 heads, 32 sectors/track, 8727 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1          16       16368    6  FAT16
/dev/sda2              17         971      977920   82  Linux swap

We will now create the root partition. Again, just use the n command.

Command (m for help): n
Command action
  e   extended
  p   primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (972-8727, default 972): 972
Last cylinder or +size or +sizeM or +sizeK (972-8727, default 8727): 8727

After these steps you should see a layout similar to the following:

Command (m for help): p

Disk /dev/sda: 9150 MB, 9150996480 bytes
64 heads, 32 sectors/track, 8727 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1          16       16368    6  FAT16
/dev/sda2              17         971      977920   82  Linux swap
/dev/sda3             972        8727     7942144   83  Linux

Save fdisk by typing w. This will also save your partition layout.

Command (m for help): w

Now that your partitions are created, you can continue with Creating Filesystems.

Now that your partitions are created, it is time to place a filesystem on them. If you don't care about what filesystem to choose and are happy with what we use as default in this handbook, continue with Applying a Filesystem to a Partition. Otherwise read on to learn about the available filesystems...

To create a filesystem on a partition or volume, there are tools available for each possible filesystem:

For instance, to have the root partition (/dev/sda2 in our example) in ext3, you would use:

# mke2fs -j /dev/sda2

Now create the filesystems on your newly created partitions (or logical volumes).

mkswap is the command that is used to initialize swap partitions:

# mkswap /dev/sda1

To activate the swap partition, use swapon:

# swapon /dev/sda1

Create and activate the swap with the commands mentioned above.