en/handbook/hb-install-ppc64-disk.xml

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<sections>

<abstract>
To be able to install Gentoo, you must create the necessary partitions.
This chapter describes how to partition a disk for future usage.
</abstract>

<version>14</version>
<date>2013-02-23</date>

<section>
<title>Introduction to Block Devices</title>

<subsection>
<include href="hb-install-blockdevices.xml"/>
</subsection>

<subsection>
<title>Partitions and Slices</title>
<body>

<p>
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 most systems,
these are called <e>partitions</e>. Other architectures use a similar technique,
called <e>slices</e>.
</p>

</body>
</subsection>
</section>
<section>
<title>Designing a Partitioning Scheme</title>
<subsection>
<title>Default Partitioning Scheme</title>
<body>

<p>
If you are not interested in drawing up a partitioning scheme for your system,
you can use the partitioning scheme we use throughout this book:
</p>

<table>
<tr>
  <th>Partition</th>
  <th>Filesystem</th>
  <th>Size</th>
  <th>Description</th>
</tr>
<tr>
  <ti><path>/dev/sda1</path></ti>
  <ti>Partition map</ti>
  <ti>31.5k</ti>
  <ti>Partition map</ti>
</tr>
<tr>
  <ti><path>/dev/sda2</path></ti>
  <ti>(bootstrap)</ti>
  <ti>800k</ti>
  <ti>Apple_Bootstrap</ti>
</tr>
<tr>
  <ti><path>/dev/sda3</path></ti>
  <ti>(swap)</ti>
  <ti>512M</ti>
  <ti>Swap partition</ti>
</tr>
<tr>
  <ti><path>/dev/sda4</path></ti>
  <ti>ext3 or ext4</ti>
  <ti>Rest of the disk</ti>
  <ti>Root partition</ti>
</tr>
</table>

<note>
There are some partitions named like this: <path>Apple_Driver43</path>,
<path>Apple_Driver_ATA</path>, <path>Apple_FWDriver</path>,
<path>Apple_Driver_IOKit</path>, and <path>Apple_Patches</path>. If you are not
planning to use MacOS 9 you can delete them, because MacOS X and Linux don't
need them.  You might have to use parted in order to delete them, as mac-fdisk
can't delete them yet.
</note>

<p>
If you are interested in knowing how big a partition should be, or even how 
many partitions you need, read on. Otherwise continue now with
<uri link="#mac-fdisk">Apple G5: Using mac-fdisk to Partition your
Disk</uri> or <uri link="#fdisk">IBM pSeries: using fdisk to Partition
your Disk</uri>
</p>

</body>
</subsection>
<subsection>
<title>How Many and How Big?</title>
<body>

<p>
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
<path>/home</path> separate as it increases security and makes backups easier.
If you are installing Gentoo to perform as a mailserver, your <path>/var</path>
should be separate as all mails are stored inside <path>/var</path>. A good
choice of filesystem will then maximise your performance. Gameservers will have
a separate <path>/opt</path> as most gaming servers are installed there. The
reason is similar for <path>/home</path>: security and backups. You will
definitely want to keep <path>/usr</path> 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.
</p>

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

<ul>
<li>
  You can choose the best performing filesystem for each partition or volume
</li>
<li>
  Your entire system cannot run out of free space if one defunct tool is
  continuously writing files to a partition or volume
</li>
<li>
  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)
</li>
<li>
  Security can be enhanced by mounting some partitions or volumes read-only, 
  nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
</li>
</ul>

<p>
However, multiple partitions have disadvantages as well. If not configured
properly, you will have a system with lots of free space on one partition and
none on another. Another nuisance is that separate partitions - especially
for important mountpoints like <path>/usr</path> or <path>/var</path> - often
require the administrator to boot with an initramfs to mount the partition
before other boot scripts start. This isn't always the case though, so your
results may vary.
</p>

<p>
There is also a 15-partition limit for SCSI and SATA.
</p>

</body>
</subsection>
</section>
<section id="mac-fdisk">
<title>Default: Using mac-fdisk (Apple G5) to Partition your Disk</title>
<body>

<p>
At this point, create your partitions using <c>mac-fdisk</c>:
</p>

<pre caption="Starting mac-fdisk">
# <i>mac-fdisk /dev/sda</i>
</pre>

<p>
First delete the partitions you have cleared previously to make room for your
Linux partitions. Use <c>d</c> in <c>mac-fdisk</c> to delete those partition(s).
It will ask for the partition number to delete.
</p>

<p>
Second, create an <e>Apple_Bootstrap</e> partition by using <c>b</c>. It will
ask for what block you want to start. Enter the number of your first free
partition, followed by a <c>p</c>. For instance this is <c>2p</c>.
</p>

<note>
This partition is <e>not</e> a "boot" partition. It is not used by Linux at all;
you don't have to place any filesystem on it and you should never mount it. PPC
users don't need an extra partition for <path>/boot</path>.
</note>

<p>
Now create a swap partition by pressing <c>c</c>. Again <c>mac-fdisk</c> will
ask for what block you want to start this partition from. As we used <c>2</c>
before to create the Apple_Bootstrap partition, you now have to enter
<c>3p</c>. When you're asked for the size, enter <c>512M</c> (or whatever size
you want). When asked for a name, enter <c>swap</c> (mandatory).
</p>

<p>
To create the root partition, enter <c>c</c>, followed by <c>4p</c> to select
from what block the root partition should start. When asked for the size, enter
<c>4p</c> again. <c>mac-fdisk</c> will interpret this as "Use all available
space". When asked for the name, enter <c>root</c> (mandatory).
</p>

<p>
To finish up, write the partition to the disk using <c>w</c> and <c>q</c> to
quit <c>mac-fdisk</c>.
</p>

<note>
To make sure everything is ok, you should run mac-fdisk once more and check
whether all the partitions are there. If you don't see any of the partitions you
created, or the changes you made, you should reinitialize your partitions by
pressing <c>i</c> in mac-fdisk. Note that this will recreate the partition map
and thus remove all your partitions. 
</note>
    
<p>
Now that your partitions are created, you can continue with <uri
link="#filesystems">Creating Filesystems</uri>.
</p>

</body>
</section>
<section id="fdisk">
<title>IBM pSeries, iSeries and OpenPower: using fdisk to Partition your Disk</title>
<subsection>
<body>

<note>
If you are planning to use a RAID disk array for your Gentoo installation and 
you are using POWER5-based hardware, you should now run <c>iprconfig</c> to 
format the disks to Advanced Function format and create the disk array. You
should emerge <c>iprutils</c> after your install is complete.
</note>

<p>
If you have an ipr-based SCSI adapter, you should start the ipr utilities now.
</p>

<pre caption="Starting ipr utilities">
# <i>/etc/init.d/iprinit start</i>
</pre>

<p>
The following parts explain how to create the example partition layout
described previously, namely:
</p>

<table>
<tr>
  <th>Partition</th>
  <th>Description</th>
</tr>
<tr>
  <ti><path>/dev/sda1</path></ti>
  <ti>PPC PReP Boot partition</ti>
</tr>
<tr>
  <ti><path>/dev/sda2</path></ti>
  <ti>Swap partition</ti>
</tr>
<tr>
  <ti><path>/dev/sda3</path></ti>
  <ti>Root partition</ti>
</tr>
</table>

<p>
Change your partition layout according to your own preference.
</p>

</body>
</subsection>
<subsection>
<title>Viewing the Current Partition Layout</title>
<body>

<p>
<c>fdisk</c> is a popular and powerful tool to split your disk into
partitions.  Fire up <c>fdisk</c> on your disk (in our example, we
use <path>/dev/sda</path>):
</p>

<pre caption="Starting fdisk">
# <i>fdisk /dev/sda</i>
</pre>

<p>
Once in <c>fdisk</c>, you'll be greeted with a prompt that looks like
this:
</p>

<pre caption="fdisk prompt">
Command (m for help):
</pre>

<p>
If you still have an AIX partition layout on your system, you will get the
following error message:
</p>

<pre caption="Error message from fdisk">
  There is a valid AIX label on this disk.
  Unfortunately Linux cannot handle these
  disks at the moment.  Nevertheless some
  advice:
  1. fdisk will destroy its contents on write.
  2. Be sure that this disk is NOT a still vital
     part of a volume group. (Otherwise you may
     erase the other disks as well, if unmirrored.)
  3. Before deleting this physical volume be sure
     to remove the disk logically from your AIX
     machine.  (Otherwise you become an AIXpert).

Command (m for help):
</pre>

<p>
Don't worry, you can create a new empty DOS partition table by pressing
<c>o</c>.
</p>

<warn>
This will destroy any installed AIX version!
</warn>

<p>
Type <c>p</c> to display your disk current partition configuration:
</p>

<pre caption="An example partition configuration">
Command (m for help): <i>p</i>

Disk /dev/sda: 30.7 GB, 30750031872 bytes
141 heads, 63 sectors/track, 6761 cylinders
Units = cylinders of 8883 * 512 = 4548096 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1          12       53266+  83  Linux
/dev/sda2              13         233      981571+  82  Linux swap
/dev/sda3             234         674     1958701+  83  Linux
/dev/sda4             675        6761    27035410+   5  Extended
/dev/sda5             675        2874     9771268+  83  Linux
/dev/sda6            2875        2919      199836   83  Linux
/dev/sda7            2920        3008      395262   83  Linux
/dev/sda8            3009        6761    16668918   83  Linux

Command (m for help):
</pre>

<p>
This particular disk is configured to house six Linux filesystems
(each with a corresponding partition listed as "Linux") as well as a
swap partition (listed as "Linux swap").
</p>

</body>
</subsection>
<subsection>
<title>Removing all Partitions</title>
<body>

<p>
We will first remove all existing partitions from the disk. Type
<c>d</c> to delete a partition. For instance, to delete an existing
<path>/dev/sda1</path>:
</p>

<note>
If you don't want to delete all partitions just delete those you want to delete.
At this point you should create a backup of your data to avoid losing it.
</note>

<pre caption="Deleting a partition">
Command (m for help): <i>d</i>
Partition number (1-4): <i>1</i>
</pre>

<p>
The partition has been scheduled for deletion. It will no longer show up
if you type <c>p</c>, but it will not be erased until your changes have
been saved. If you made a mistake and want to abort without saving your
changes, type <c>q</c> immediately and hit Enter and your partition will
not be deleted.
</p>

<p>
Now, assuming that you do indeed want to wipe out all the partitions on
your system, repeatedly type <c>p</c> to print out a partition listing
and then type <c>d</c> and the number of the partition to delete it.
Eventually, you'll end up with a partition table with nothing in it:
</p>

<pre caption="An empty partition table">
Disk /dev/sda: 30.7 GB, 30750031872 bytes
141 heads, 63 sectors/track, 6761 cylinders
Units = cylinders of 8883 * 512 = 4548096 bytes

Device Boot    Start       End    Blocks   Id  System

Command (m for help):
</pre>

<p>
Now that the in-memory partition table is empty, we're ready to create
the partitions. We will use a default partitioning scheme as discussed
previously. Of course, don't follow these instructions to the letter if
you don't want the same partitioning scheme!
</p>

</body>
</subsection>
<subsection>
<title>Creating the PPC PReP boot partition</title>
<body>

<p>
We first create a small PReP boot partition. Type <c>n</c> to create a new
partition, then <c>p</c> to select a primary partition, followed by
<c>1</c> to select the first primary partition. When prompted for the
first cylinder, hit enter. When prompted for the last cylinder, type
<c>+7M</c> to create a partition 7 MB in size. After you've done
this, type <c>t</c> to set the partition type, <c>1</c> to select the
partition you just created and then type in <c>41</c> to set the
partition type to "PPC PReP Boot".  Finally, you'll need to mark the PReP
partition as bootable.
</p>

<note>
The PReP partition has to be smaller than 8 MB!
</note>

<pre caption="Creating the PReP boot partition">
Command (m for help): <i>p</i>

Disk /dev/sda: 30.7 GB, 30750031872 bytes
141 heads, 63 sectors/track, 6761 cylinders
Units = cylinders of 8883 * 512 = 4548096 bytes

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): <i>n</i>
Command action
      e   extended
      p   primary partition (1-4)
<i>p</i>
Partition number (1-4): <i>1</i>
First cylinder (1-6761, default 1): 
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-6761, default
6761): <i>+8M</i>

Command (m for help): <i>t</i>
Selected partition 1
Hex code (type L to list codes): <i>41</i>
Changed system type of partition 1 to 41 (PPC PReP Boot)

Command (m for help): <i>a</i>
Partition number (1-4): <i>1</i>
Command (m for help):
</pre>

<p>
Now, when you type <c>p</c>, you should see the following partition information:
</p>

<pre caption="Created boot partition">
Command (m for help): <i>p</i>

Disk /dev/sda: 30.7 GB, 30750031872 bytes
141 heads, 63 sectors/track, 6761 cylinders
Units = cylinders of 8883 * 512 = 4548096 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1  *            1           3       13293   41  PPC PReP Boot

Command (m for help):
</pre>
</body>
</subsection>
<subsection>
<title>Creating the Swap Partition</title>
<body>

<p>
Let's now create the swap partition. To do this, type <c>n</c> to create
a new partition, then <c>p</c> to tell fdisk that you want a primary
partition. Then type <c>2</c> to create the second primary partition,
<path>/dev/sda2</path> in our case. When prompted for the first
cylinder, hit enter. When prompted for the last cylinder, type
<c>+512M</c> to create a partition 512MB in size. After you've done
this, type <c>t</c> to set the partition type, <c>2</c> to select the
partition you just created and then type in <c>82</c> to set the
partition type to "Linux Swap". After completing these steps, typing
<c>p</c> should display a partition table that looks similar to this:
</p>

<pre caption="Partition listing after creating a swap partition">
Command (m for help): <i>p</i>

Disk /dev/sda: 30.7 GB, 30750031872 bytes
141 heads, 63 sectors/track, 6761 cylinders
Units = cylinders of 8883 * 512 = 4548096 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1           3       13293   41  PPC PReP Boot
/dev/sda2               4         117      506331   82  Linux swap

Command (m for help):
</pre>

</body>
</subsection>
<subsection>
<title>Creating the Root Partition</title>
<body>

<p>
Finally, let's create the root partition. To do this, type <c>n</c> to
create a new partition, then <c>p</c> to tell fdisk that you want a
primary partition. Then type <c>3</c> to create the third primary
partition, <path>/dev/sda3</path> in our case. When prompted for the
first cylinder, hit enter. When prompted for the last cylinder, hit
enter to create a partition that takes up the rest of the remaining
space on your disk. After completing these steps, typing <c>p</c> should
display a partition table that looks similar to this:
</p>

<pre caption="Partition listing after creating the root partition">
Command (m for help): <i>p</i>

Disk /dev/sda: 30.7 GB, 30750031872 bytes
141 heads, 63 sectors/track, 6761 cylinders
Units = cylinders of 8883 * 512 = 4548096 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1           3       13293   41  PPC PReP Boot
/dev/sda2               4         117      506331   82  Linux swap
/dev/sda3             118        6761    29509326   83  Linux

Command (m for help):
</pre>
</body>
</subsection>
<subsection>
<title>Saving the Partition Layout</title>
<body>

<p>
To save the partition layout and exit <c>fdisk</c>, type <c>w</c>.
</p>

<pre caption="Save and exit fdisk">
Command (m for help): <i>w</i>
</pre>

<p>
Now that your partitions are created, you can continue with <uri
link="#filesystems">Creating Filesystems</uri>.
</p>

</body>
</subsection>
</section>
<section id="filesystems">
<title>Creating Filesystems</title>
<subsection>
<title>Introduction</title>
<body>

<p>
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 <uri 
link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
Otherwise read on to learn about the available filesystems...
</p>

</body>
</subsection>

<subsection>
<include href="hb-install-filesystems.xml"/>
</subsection>

<subsection id="filesystems-apply">
<title>Applying a Filesystem to a Partition</title>
<body>

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

<table>
<tr>
  <th>Filesystem</th>
  <th>Creation Command</th>
</tr>
<tr>
  <ti>ext2</ti>
  <ti><c>mke2fs</c></ti>
</tr>
<tr>
  <ti>ext3</ti>
  <ti><c>mke2fs -j</c></ti>
</tr>
<tr>
  <ti>ext4</ti>
  <ti><c>mkfs.ext4</c></ti>
</tr>
<tr>
  <ti>reiserfs</ti>
  <ti><c>mkreiserfs</c></ti>
</tr>
<tr>
  <ti>xfs</ti>
  <ti><c>mkfs.xfs</c></ti>
</tr>
<tr>
  <ti>jfs</ti>
  <ti><c>mkfs.jfs</c></ti>
</tr>
</table>

<p>
For instance, to have the root partition (<path>/dev/sda4</path> in our example)
in ext4 (as in our example), you would use:
</p>

<pre caption="Applying a filesystem on a partition">
# <i>mkfs.ext4 /dev/sda4</i>
</pre>

<p>
Now create the filesystems on your newly created partitions (or logical
volumes).
</p>

<impo>
If you choose to use ReiserFS for <path>/</path>, do not change its default
block size if you will also be using <c>yaboot</c> as your bootloader, as
explained in <uri link="?part=1&amp;chap=10">Configuring the Bootloader</uri>.
</impo>

</body>
</subsection>
<subsection>
<title>Activating the Swap Partition</title>
<body>

<p>
<c>mkswap</c> is the command that is used to initialize swap partitions:
</p>

<pre caption="Creating a Swap signature">
# <i>mkswap /dev/sda3</i>
</pre>

<p>
To activate the swap partition, use <c>swapon</c>:
</p>

<pre caption="Activating the swap partition">
# <i>swapon /dev/sda3</i>
</pre>

<p>
Create and activate the swap with the commands mentioned above.
</p>

</body>
</subsection>
</section>
<section>
<title>Mounting</title>
<body>

<p>
Now that your partitions are initialized and are housing a filesystem, it is
time to mount those partitions. Use the <c>mount</c> command. Don't forget to
create the necessary mount directories for every partition you created. As an
example we create a mount point and mount the root partition:
</p>

<pre caption="Mounting partitions">
# <i>mkdir /mnt/gentoo</i>
# <i>mount /dev/sda4 /mnt/gentoo</i> 
</pre>

<note>
If you want your <path>/tmp</path> to reside on a separate partition, be sure to
change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
also holds for <path>/var/tmp</path>.
</note>

<p>
Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
Installation Files</uri>.
</p>

</body>
</section>
</sections>