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<?xml version='1.0' encoding='UTF-8'?> |
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<!DOCTYPE sections SYSTEM "/dtd/book.dtd"> |
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<!-- The content of this document is licensed under the CC-BY-SA license --> |
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<!-- See http://creativecommons.org/licenses/by-sa/1.0 --> |
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<!-- $Header: /home/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-alpha-disk.xml,v 1.1 2004/04/02 08:14:45 swift Exp $ --> |
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|
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<sections> |
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<section> |
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<title>Introduction to Block Devices</title> |
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<subsection> |
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<title>Block Devices</title> |
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<body> |
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|
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<p> |
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We'll take a good look at disk-oriented aspects of Gentoo Linux |
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and Linux in general, including Linux filesystems, partitions and block devices. |
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Then, once you're familiar with the ins and outs of disks and filesystems, |
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you'll be guided through the process of setting up partitions and filesystems |
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for your Gentoo Linux installation. |
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</p> |
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|
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<p> |
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To begin, we'll introduce <e>block devices</e>. The most famous block device is |
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probably the one that represents the first SCSI HD in a Linux system, namely |
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<path>/dev/sda</path>. |
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</p> |
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|
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<p> |
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The block devices above represent an abstract interface to the disk. User |
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programs can use these block devices to interact with your disk without worrying |
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about whether your drives are IDE, SCSI or something else. The program can |
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simply address the storage on the disk as a bunch of contiguous, |
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randomly-accessible 512-byte blocks. |
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</p> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Slices</title> |
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<body> |
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|
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<p> |
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Although it is theoretically possible to use a full disk to house your Linux |
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system, this is almost never done in practice. Instead, full disk block devices |
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are split up in smaller, more manageable block devices. On Alpha systems, |
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these are called <e>slices</e>. |
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</p> |
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|
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</body> |
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</subsection> |
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</section> |
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<section> |
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<title>Designing a Partitioning Scheme</title> |
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<subsection> |
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<title>Default Partitioning Scheme</title> |
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<body> |
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|
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<p> |
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As an example we use the following slice layout: |
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</p> |
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|
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<table> |
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<tr> |
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<th>Slice</th> |
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<th>Description</th> |
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</tr> |
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<tr> |
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<ti><path>/dev/sdaa</path></ti> |
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<ti>Swap slice</ti> |
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</tr> |
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<tr> |
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<ti><path>/dev/sdab</path></ti> |
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<ti>Root slice</ti> |
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</tr> |
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<tr> |
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<ti><path>/dev/sdac</path></ti> |
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<ti>Full disk (required)</ti> |
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</tr> |
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</table> |
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|
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|
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<p> |
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If you are interested in knowing how big a partition should be, or even how |
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many partitions (or volumes) you need, read on. Otherwise continue now with |
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<uri link="#fdisk">Using fdisk to Partition your Disk</uri>. |
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</p> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>How Many and How Big?</title> |
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<body> |
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|
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<p> |
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The number of partitions is highly dependent on your environment. For instance, |
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if you have lots of users, you will most likely want to have your |
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<path>/home</path> separate as it increases security and makes backups easier. |
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If you are installing Gentoo to perform as a mailserver, your |
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<path>/var</path> should be separate as all mails are stored inside |
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<path>/var</path>. A good choice of filesystem will then maximise your |
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performance. Gameservers will have a separate <path>/opt</path> as most gaming |
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servers are installed there. The reason is similar for <path>/home</path>: |
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security and backups. |
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</p> |
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|
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<p> |
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As you can see, it very much depends on what you want to achieve. Separate |
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partitions or volumes have the following advantages: |
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</p> |
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|
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<ul> |
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<li> |
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You can choose the most performant filesystem for each partition or volume |
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</li> |
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<li> |
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Your entire system cannot run out of free space if one defunct tool is |
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continuously writing files to a partition or volume |
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</li> |
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<li> |
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If necessary, file system checks are reduced in time, as multiple checks can |
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be done in parallel (although this advantage is more with multiple disks than |
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it is with multiple partitions) |
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</li> |
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<li> |
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Security can be enhanced by mounting some partitions or volumes read-only, |
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nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc. |
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</li> |
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</ul> |
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|
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<p> |
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However, multiple partitions have one big disadvantage: if not configured |
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properly, you might result in having a system with lots |
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of free space on one partition and none on another. |
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</p> |
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|
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</body> |
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</subsection> |
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</section> |
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<section id="fdisk"> |
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<title>Using fdisk on Alpha to Partition your Disk</title> |
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<subsection> |
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<body> |
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|
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<p> |
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The following parts explain how to create the example slice layout described |
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previously, namely: |
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</p> |
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|
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<table> |
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<tr> |
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<th>Slice</th> |
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<th>Description</th> |
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</tr> |
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<tr> |
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<ti><path>/dev/sdaa</path></ti> |
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<ti>Swap slice</ti> |
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</tr> |
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<tr> |
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<ti><path>/dev/sdab</path></ti> |
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<ti>Root slice</ti> |
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</tr> |
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<tr> |
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<ti><path>/dev/sdac</path></ti> |
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<ti>Full disk (required)</ti> |
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</tr> |
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</table> |
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|
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<p> |
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Change your slice layout according to your own will. |
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</p> |
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|
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Identifying Available Disks</title> |
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<body> |
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|
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<p> |
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To figure out what disks you have running, use the following commands: |
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</p> |
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|
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<pre caption="Identifying available disks"> |
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<comment>(For IDE disks)</comment> # <i>dmesg | grep 'drive$'</i> |
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<comment>(For SCSI disks)</comment> # <i>dmesg | grep 'scsi'</i> |
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</pre> |
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|
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<p> |
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From this output you should be able to see what disks were detected and their |
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respective <path>/dev</path> entry. In the following parts we assume that the |
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disk is a SCSI disk on <path>/dev/sda</path>. |
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</p> |
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|
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<p> |
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Now fire up <c>fdisk</c>: |
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</p> |
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|
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<pre caption="Starting fdisk"> |
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# <i>fdisk /dev/sda</i> |
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</pre> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Deleting All Slices</title> |
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<body> |
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|
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<p> |
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We start with deleting all slices <e>except</e> the 'c'-slice. The following |
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shows how to delete a slice (in the example we use 'a'). Repeat the process to |
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delete all other slices (again, except the 'c'-slice). |
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</p> |
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|
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<p> |
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Use <c>p</c> to view all existing slices. <c>d</c> is used to delete a slice. |
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</p> |
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|
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<pre caption="Deleting a slice"> |
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BSD disklabel command (m for help): <i>p</i> |
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|
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8 partitions: |
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# start end size fstype [fsize bsize cpg] |
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a: 1 235* 234* 4.2BSD 1024 8192 16 |
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b: 235* 469* 234* swap |
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c: 1 5290* 5289* unused 0 0 |
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d: 469* 2076* 1607* unused 0 0 |
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e: 2076* 3683* 1607* unused 0 0 |
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f: 3683* 5290* 1607* unused 0 0 |
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g: 469* 1749* 1280 4.2BSD 1024 8192 16 |
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h: 1749* 5290* 3541* unused 0 0 |
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|
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BSD disklabel command (m for help): <i>d</i> |
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Partition (a-h): <i>a</i> |
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</pre> |
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|
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<p> |
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After repeating this process for all slices, a listing should show you something |
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similar to this: |
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</p> |
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|
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<pre caption="Viewing an empty scheme"> |
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BSD disklabel command (m for help): <i>p</i> |
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|
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3 partitions: |
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# start end size fstype [fsize bsize cpg] |
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c: 1 5290* 5289* unused 0 0 |
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</pre> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Creating the Swap Slice</title> |
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<body> |
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|
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<p> |
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On Alpha based systems you don't need a separate boot partition. However, the |
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first cylinder cannot be used as the <c>aboot</c> image will be placed there. |
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</p> |
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|
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<p> |
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We will create a swap slice starting at the third cylinder, with a total |
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size of 1 Gbyte. Use <c>n</c> to create a new slice. After creating the slice, |
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we will change its type to <c>1</c>, meaning <e>swap</e>. |
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</p> |
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|
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<pre caption="Creating the swap slice"> |
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BSD disklabel command (m for help): <i>n</i> |
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Partition (a-p): <i>a</i> |
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First cylinder (1-5290, default 1): <i>3</i> |
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Last cylinder or +size or +sizeM or +sizeK (3-5290, default 5290): <i>+1024M</i> |
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|
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BSD disklabel command (m for help): <i>t</i> |
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Partition (a-c): <i>a</i> |
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Hex code (type L to list codes): <i>1</i> |
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</pre> |
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|
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<p> |
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After these steps you should see a layout similar to the following: |
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</p> |
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|
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<pre caption="Slice layout after creating the swap slice"> |
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BSD disklabel command (m for help): <i>p</i> |
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|
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3 partitions: |
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# start end size fstype [fsize bsize cpg] |
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a: 3 1003 1001 swap |
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c: 1 5290* 5289* unused 0 0 |
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</pre> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Create the Root Slice</title> |
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<body> |
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|
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<p> |
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We will now create the root slice, starting from the first cylinder <e>after</e> |
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the swap slice. Use the <c>p</c> command to view where the swap slice ends. In |
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our example, this is at 1003, making the root partition start at 1004. |
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</p> |
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|
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<p> |
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Another problem is that there is currently a bug in <c>fdisk</c> making it think |
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the number of available cylinders is one above the real number of cylinders. In |
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other words, when you are asked for the last cylinder, decrease the cylinder |
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number (in this example: 5290) with one. |
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</p> |
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|
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<p> |
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When the partition is created, we change the type to <c>8</c>, for <e>ext2</e>. |
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</p> |
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|
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<pre caption="Creating the root slice"> |
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D disklabel command (m for help): <i>n</i> |
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Partition (a-p): <i>b</i> |
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First cylinder (1-5290, default 1): <i>1004</i> |
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Last cylinder or +size or +sizeM or +sizeK (1004-5290, default 5290): <i>5289</i> |
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|
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BSD disklabel command (m for help): <i>t</i> |
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Partition (a-c): <i>b</i> |
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Hex code (type L to list codes): <i>8</i> |
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</pre> |
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|
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<p> |
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Your slice layout should now be similar to this: |
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</p> |
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|
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<pre caption="Viewing the slice layout"> |
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BSD disklabel command (m for help): <i>p</i> |
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|
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3 partitions: |
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# start end size fstype [fsize bsize cpg] |
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a: 3 1003 1001 swap |
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b: 1004 5289 4286 ext2 |
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c: 1 5290* 5289* unused 0 0 |
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</pre> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Save the Slice Layout and Exit</title> |
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<body> |
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|
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<p> |
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Save <c>fdisk</c> by typing <c>w</c>. This will also save your slice layout. |
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</p> |
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|
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<pre caption="Save and exit fdisk"> |
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Command (m for help): <i>w</i> |
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</pre> |
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|
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<p> |
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Now that your slices are created, you can now continue with <uri |
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link="#filesystems">Creating Filesystems</uri>. |
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</p> |
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|
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</body> |
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</subsection> |
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</section> |
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<section id="filesystems"> |
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<title>Creating Filesystems</title> |
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<subsection> |
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<title>Introduction</title> |
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<body> |
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|
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<p> |
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Now that your partitions are created, it is time to place a filesystem on them. |
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If you don't care about what filesystem to choose and are happy with what we use |
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as default in this handbook, continue with <uri |
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link="#filesystems-apply">Applying a Filesystem to a Partition</uri>. |
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Otherwise read on to learn about the available filesystems... |
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</p> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Filesystems?</title> |
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<body> |
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|
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<p> |
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Several filesystems are available. Most of them are found stable on the |
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Alpha architecture. |
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</p> |
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|
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<p> |
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<b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata |
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journaling, which means that routine ext2 filesystem checks at startup time can |
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be quite time-consuming. There is now quite a selection of newer-generation |
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journaled filesystems that can be checked for consistency very quickly and are |
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thus generally preferred over their non-journaled counterparts. Journaled |
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filesystems prevent long delays when you boot your system and your filesystem |
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happens to be in an inconsistent state. |
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</p> |
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|
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<p> |
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<b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata |
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journaling for fast recovery in addition to other enhanced journaling modes like |
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full data and ordered data journaling. ext3 is a very good and reliable |
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filesystem. It has an additional hashed b-tree indexing option that enables |
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high performance in almost all situations. In short, ext3 is an excellent |
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filesystem. |
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</p> |
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|
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<p> |
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<b>ReiserFS</b> is a B*-tree based filesystem that has very good overall |
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performance and greatly outperforms both ext2 and ext3 when dealing with small |
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files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales |
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extremely well and has metadata journaling. As of kernel 2.4.18+, ReiserFS is |
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solid and usable as both general-purpose filesystem and for extreme cases such |
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as the creation of large filesystems, the use of many small files, very large |
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files and directories containing tens of thousands of files. |
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</p> |
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|
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<p> |
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<b>XFS</b> is a filesystem with metadata journaling that is fully supported |
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under Gentoo Linux's xfs-sources kernel. It comes with a robust feature-set and |
| 419 |
is optimized for scalability. We only recommend using this filesystem on Linux |
| 420 |
systems with high-end SCSI and/or fibre channel storage and a uninterruptible |
| 421 |
power supply. Because XFS aggressively caches in-transit data in RAM, improperly |
| 422 |
designed programs (those that don't take proper precautions when writing files |
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to disk and there are quite a few of them) can lose a good deal of data if the |
| 424 |
system goes down unexpectedly. |
| 425 |
</p> |
| 426 |
|
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<p> |
| 428 |
<b>JFS</b> is IBM's high-performance journaling filesystem. It has recently |
| 429 |
become production-ready and there hasn't been a sufficient track record to |
| 430 |
comment positively nor negatively on its general stability at this point. |
| 431 |
</p> |
| 432 |
|
| 433 |
</body> |
| 434 |
</subsection> |
| 435 |
<subsection id="filesystems-apply"> |
| 436 |
<title>Applying a Filesystem to a Partition</title> |
| 437 |
<body> |
| 438 |
|
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<p> |
| 440 |
To create a filesystem on a partition or volume, there are tools available for |
| 441 |
each possible filesystem: |
| 442 |
</p> |
| 443 |
|
| 444 |
<table> |
| 445 |
<tr> |
| 446 |
<th>Filesystem</th> |
| 447 |
<th>Creation Command</th> |
| 448 |
</tr> |
| 449 |
<tr> |
| 450 |
<ti>ext2</ti> |
| 451 |
<ti><c>mke2fs</c></ti> |
| 452 |
</tr> |
| 453 |
<tr> |
| 454 |
<ti>ext3</ti> |
| 455 |
<ti><c>mke2fs -j</c></ti> |
| 456 |
</tr> |
| 457 |
<tr> |
| 458 |
<ti>reiserfs</ti> |
| 459 |
<ti><c>mkreiserfs</c></ti> |
| 460 |
</tr> |
| 461 |
<tr> |
| 462 |
<ti>xfs</ti> |
| 463 |
<ti><c>mkfs.xfs</c></ti> |
| 464 |
</tr> |
| 465 |
<tr> |
| 466 |
<ti>jfs</ti> |
| 467 |
<ti><c>mkfs.jfs</c></ti> |
| 468 |
</tr> |
| 469 |
</table> |
| 470 |
|
| 471 |
<p> |
| 472 |
For instance, to have the root partition (<path>/dev/sdab</path> in our example) |
| 473 |
in ext3, you would use: |
| 474 |
</p> |
| 475 |
|
| 476 |
<pre caption="Applying a filesystem on a partition"> |
| 477 |
# <i>mke2fs -j /dev/sdab</i> |
| 478 |
</pre> |
| 479 |
|
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<p> |
| 481 |
Now create the filesystems on your newly created partitions (or logical |
| 482 |
volumes). |
| 483 |
</p> |
| 484 |
|
| 485 |
</body> |
| 486 |
</subsection> |
| 487 |
<subsection> |
| 488 |
<title>Activating the Swap Partition</title> |
| 489 |
<body> |
| 490 |
|
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<p> |
| 492 |
<c>mkswap</c> is the command that is used to initialize swap partitions: |
| 493 |
</p> |
| 494 |
|
| 495 |
<pre caption="Creating a Swap signature"> |
| 496 |
# <i>mkswap /dev/sdaa</i> |
| 497 |
</pre> |
| 498 |
|
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<p> |
| 500 |
To activate the swap partition, use <c>swapon</c>: |
| 501 |
</p> |
| 502 |
|
| 503 |
<pre caption="Activating the swap partition"> |
| 504 |
# <i>swapon /dev/sdaa</i> |
| 505 |
</pre> |
| 506 |
|
| 507 |
<p> |
| 508 |
Create and activate the swap now. |
| 509 |
</p> |
| 510 |
|
| 511 |
</body> |
| 512 |
</subsection> |
| 513 |
</section> |
| 514 |
<section> |
| 515 |
<title>Mounting</title> |
| 516 |
<body> |
| 517 |
|
| 518 |
<p> |
| 519 |
Now that your partitions are initialized and are housing a filesystem, it is |
| 520 |
time to mount those partitions. Use the <c>mount</c> command. Don't forget to |
| 521 |
create the necessary mount directories for every partition you created. As an |
| 522 |
example we mount the root and boot partition: |
| 523 |
</p> |
| 524 |
|
| 525 |
<pre caption="Mounting partitions"> |
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# <i>mount /dev/sdab /mnt/gentoo</i> |
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</pre> |
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|
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<note> |
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If you want your <path>/tmp</path> to reside on a separate partition, be sure to |
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change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This |
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also holds for <path>/var/tmp</path>. |
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</note> |
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|
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<p> |
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We also need to mount the proc filesystem (a virtual interface with the kernel) |
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on <path>/proc</path>. We first create the <path>/mnt/gentoo/proc</path> |
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mountpoint and then mount the filesystem: |
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</p> |
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|
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<pre caption="Creating the /mnt/gentoo/proc mountpoint"> |
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# <i>mkdir /mnt/gentoo/proc</i> |
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# <i>mount -t proc none /mnt/gentoo/proc</i> |
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</pre> |
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|
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<p> |
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Now continue with <uri link="?part=1&chap=5">Installing the Gentoo |
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Installation Files</uri>. |
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</p> |
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|
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</body> |
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</section> |
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</sections> |
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