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1 swift 1.1 <?xml version='1.0' encoding='UTF-8'?>
2     <!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3    
4     <!-- The content of this document is licensed under the CC-BY-SA license -->
5     <!-- See http://creativecommons.org/licenses/by-sa/1.0 -->
6    
7 swift 1.15 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-hppa-disk.xml,v 1.14 2005/01/04 18:11:20 swift Exp $ -->
8 swift 1.1
9     <sections>
10 swift 1.10
11 swift 1.15 <version>1.10</version>
12     <date>2005-02-20</date>
13 swift 1.10
14 swift 1.1 <section>
15     <title>Introduction to Block Devices</title>
16     <subsection>
17     <title>Block Devices</title>
18     <body>
19    
20     <p>
21     We'll take a good look at disk-oriented aspects of Gentoo Linux
22     and Linux in general, including Linux filesystems, partitions and block devices.
23     Then, once you're familiar with the ins and outs of disks and filesystems,
24     you'll be guided through the process of setting up partitions and filesystems
25     for your Gentoo Linux installation.
26     </p>
27    
28     <p>
29     To begin, we'll introduce <e>block devices</e>. The most famous block device is
30     probably the one that represents the first SCSI HD in a Linux system, namely
31     <path>/dev/sda</path>.
32     </p>
33    
34     <p>
35     The block devices above represent an abstract interface to the disk. User
36     programs can use these block devices to interact with your disk without worrying
37     about whether your drives are IDE, SCSI or something else. The program can
38     simply address the storage on the disk as a bunch of contiguous,
39     randomly-accessible 512-byte blocks.
40     </p>
41    
42     </body>
43     </subsection>
44     <subsection>
45     <title>Partitions and Slices</title>
46     <body>
47    
48     <p>
49     Although it is theoretically possible to use a full disk to house your Linux
50     system, this is almost never done in practice. Instead, full disk block devices
51     are split up in smaller, more manageable block devices. On most systems,
52     these are called <e>partitions</e>. Other architectures use a similar technique,
53     called <e>slices</e>.
54     </p>
55    
56     </body>
57     </subsection>
58     </section>
59     <section>
60     <title>Designing a Partitioning Scheme</title>
61     <subsection>
62     <title>How Many and How Big?</title>
63     <body>
64    
65     <p>
66     The number of partitions is highly dependent on your environment. For instance,
67     if you have lots of users, you will most likely want to have your
68     <path>/home</path> separate as it increases security and makes backups easier.
69     If you are installing Gentoo to perform as a mailserver, your
70     <path>/var</path> should be separate as all mails are stored inside
71     <path>/var</path>. A good choice of filesystem will then maximise your
72     performance. Gameservers will have a separate <path>/opt</path> as most gaming
73     servers are installed there. The reason is similar for <path>/home</path>:
74     security and backups.
75     </p>
76    
77     <p>
78     As you can see, it very much depends on what you want to achieve. Separate
79     partitions or volumes have the following advantages:
80     </p>
81    
82     <ul>
83     <li>
84 neysx 1.3 You can choose the best performing filesystem for each partition or volume
85 swift 1.1 </li>
86     <li>
87     Your entire system cannot run out of free space if one defunct tool is
88     continuously writing files to a partition or volume
89     </li>
90     <li>
91     If necessary, file system checks are reduced in time, as multiple checks can
92     be done in parallel (although this advantage is more with multiple disks than
93     it is with multiple partitions)
94     </li>
95     <li>
96     Security can be enhanced by mounting some partitions or volumes read-only,
97     nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
98     </li>
99     </ul>
100    
101     <p>
102     However, multiple partitions have one big disadvantage: if not configured
103     properly, you might result in having a system with lots
104 swift 1.7 of free space on one partition and none on another. There is also a 15-partition
105 swift 1.8 limit for SCSI and SATA.
106 swift 1.1 </p>
107    
108     </body>
109     </subsection>
110     </section>
111     <section>
112     <title>Using fdisk on HPPA to Partition your Disk</title>
113     <body>
114    
115     <p>
116     Use <c>fdisk</c> to create the partitions you want:
117     </p>
118    
119     <pre caption="Partitioning the disk">
120     # <i>fdisk /dev/sda</i>
121     </pre>
122    
123     <p>
124 vapier 1.9 HPPA machines use the PC standard DOS partition tables. To create a new
125     DOS partition table, simply use the <c>o</c> command.
126     </p>
127    
128     <pre caption="Creating a DOS partition table">
129     # <i>fdisk /dev/sda</i>
130    
131     Command (m for help): <i>o</i>
132     Building a new DOS disklabel.
133     </pre>
134    
135     <p>
136     PALO (the HPPA bootloader) needs a special partition to work. You have
137 swift 1.13 to create a partition of at least 16MB at the beginning of your disk.
138 vapier 1.9 The partition type must be of type <e>f0</e> (Linux/PA-RISC boot).
139 swift 1.1 </p>
140    
141     <impo>
142     If you ignore this and continue without a special PALO partition, your system
143 swift 1.13 will stop loving you and fail to start. Also, if your disk is larger than 2GB,
144     make sure that the boot partition is in the first 2GB of your disk. PALO is
145     unable to read a kernel after the 2GB limit.
146 swift 1.1 </impo>
147    
148 vapier 1.9 <pre caption="A simple default partition schema">
149     # <i>cat /etc/fstab</i>
150     /dev/sda2 /boot ext3 noauto,noatime 1 1
151     /dev/sda3 none swap sw 0 0
152     /dev/sda4 / ext3 noatime 0 0
153    
154     # <i>fdisk /dev/sda</i>
155    
156     Command (m for help): <i>p</i>
157    
158     Disk /dev/sda: 4294 MB, 4294816768 bytes
159     133 heads, 62 sectors/track, 1017 cylinders
160     Units = cylinders of 8246 * 512 = 4221952 bytes
161    
162     Device Boot Start End Blocks Id System
163     /dev/sda1 1 8 32953 f0 Linux/PA-RISC boot
164     /dev/sda2 9 20 49476 83 Linux
165     /dev/sda3 21 70 206150 82 Linux swap
166     /dev/sda4 71 1017 3904481 83 Linux
167     </pre>
168    
169 swift 1.1 <p>
170     Now that your partitions are created, you can now continue with <uri
171     link="#filesystems">Creating Filesystems</uri>.
172     </p>
173    
174     </body>
175     </section>
176     <section id="filesystems">
177     <title>Creating Filesystems</title>
178     <subsection>
179     <title>Introduction</title>
180     <body>
181    
182     <p>
183     Now that your partitions are created, it is time to place a filesystem on them.
184     If you don't care about what filesystem to choose and are happy with what we use
185     as default in this handbook, continue with <uri
186     link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
187     Otherwise read on to learn about the available filesystems...
188     </p>
189    
190     </body>
191     </subsection>
192     <subsection>
193     <title>Filesystems?</title>
194     <body>
195    
196     <p>
197 dertobi123 1.5 Several filesystems are available. Ext2, ext3, XFS and reiserfs are found stable on
198 swift 1.1 the HPPA architecture. The others are very experimental.
199     </p>
200    
201     <p>
202     <b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata
203     journaling, which means that routine ext2 filesystem checks at startup time can
204     be quite time-consuming. There is now quite a selection of newer-generation
205     journaled filesystems that can be checked for consistency very quickly and are
206     thus generally preferred over their non-journaled counterparts. Journaled
207     filesystems prevent long delays when you boot your system and your filesystem
208     happens to be in an inconsistent state.
209     </p>
210    
211     <p>
212     <b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata
213     journaling for fast recovery in addition to other enhanced journaling modes like
214     full data and ordered data journaling. ext3 is a very good and reliable
215     filesystem. It has an additional hashed b-tree indexing option that enables
216     high performance in almost all situations. In short, ext3 is an excellent
217     filesystem.
218     </p>
219    
220     <p>
221     <b>ReiserFS</b> is a B*-tree based filesystem that has very good overall
222     performance and greatly outperforms both ext2 and ext3 when dealing with small
223     files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales
224     extremely well and has metadata journaling. As of kernel 2.4.18+, ReiserFS is
225     solid and usable as both general-purpose filesystem and for extreme cases such
226     as the creation of large filesystems, the use of many small files, very large
227     files and directories containing tens of thousands of files.
228     </p>
229    
230     <p>
231 neysx 1.4 <b>XFS</b> is a filesystem with metadata journaling which comes with a robust
232     feature-set and is optimized for scalability. We only recommend using this
233     filesystem on Linux systems with high-end SCSI and/or fibre channel storage and
234     an uninterruptible power supply. Because XFS aggressively caches in-transit data
235     in RAM, improperly designed programs (those that don't take proper precautions
236     when writing files to disk and there are quite a few of them) can lose a good
237     deal of data if the system goes down unexpectedly.
238 swift 1.1 </p>
239    
240     <p>
241     <b>JFS</b> is IBM's high-performance journaling filesystem. It has recently
242     become production-ready and there hasn't been a sufficient track record to
243     comment positively nor negatively on its general stability at this point.
244     </p>
245    
246     </body>
247     </subsection>
248     <subsection id="filesystems-apply">
249     <title>Applying a Filesystem to a Partition</title>
250     <body>
251    
252     <p>
253     To create a filesystem on a partition or volume, there are tools available for
254     each possible filesystem:
255     </p>
256    
257     <table>
258     <tr>
259     <th>Filesystem</th>
260     <th>Creation Command</th>
261     </tr>
262     <tr>
263     <ti>ext2</ti>
264     <ti><c>mke2fs</c></ti>
265     </tr>
266     <tr>
267     <ti>ext3</ti>
268     <ti><c>mke2fs -j</c></ti>
269     </tr>
270     <tr>
271     <ti>reiserfs</ti>
272     <ti><c>mkreiserfs</c></ti>
273     </tr>
274     <tr>
275     <ti>xfs</ti>
276     <ti><c>mkfs.xfs</c></ti>
277     </tr>
278     <tr>
279     <ti>jfs</ti>
280     <ti><c>mkfs.jfs</c></ti>
281     </tr>
282     </table>
283    
284     <p>
285 dertobi123 1.2 For instance, to have the boot partition (<path>/dev/sda2</path> in our
286     example) in ext2 and the root partition (<path>/dev/sda4</path> in our example)
287 swift 1.1 in ext3 (as in our example), you would use:
288     </p>
289    
290     <pre caption="Applying a filesystem on a partition">
291 dertobi123 1.2 # <i>mke2fs /dev/sda2</i>
292     # <i>mke2fs -j /dev/sda4</i>
293 swift 1.1 </pre>
294    
295     <p>
296     Now create the filesystems on your newly created partitions (or logical
297     volumes).
298     </p>
299    
300     </body>
301     </subsection>
302     <subsection>
303     <title>Activating the Swap Partition</title>
304     <body>
305    
306     <p>
307     <c>mkswap</c> is the command that is used to initialize swap partitions:
308     </p>
309    
310     <pre caption="Creating a Swap signature">
311 dertobi123 1.2 # <i>mkswap /dev/sda3</i>
312 swift 1.1 </pre>
313    
314     <p>
315     To activate the swap partition, use <c>swapon</c>:
316     </p>
317    
318     <pre caption="Activating the swap partition">
319 dertobi123 1.2 # <i>swapon /dev/sda3</i>
320 swift 1.1 </pre>
321    
322     <p>
323 swift 1.15 Create and activate the swap with the commands mentioned above.
324 swift 1.1 </p>
325    
326     </body>
327     </subsection>
328     </section>
329     <section>
330     <title>Mounting</title>
331     <body>
332    
333     <p>
334     Now that your partitions are initialized and are housing a filesystem, it is
335     time to mount those partitions. Use the <c>mount</c> command. Don't forget to
336     create the necessary mount directories for every partition you created. As an
337     example we mount the root and boot partition:
338     </p>
339    
340     <pre caption="Mounting partitions">
341 dertobi123 1.2 # <i>mount /dev/sda4 /mnt/gentoo</i>
342 swift 1.1 # <i>mkdir /mnt/gentoo/boot</i>
343 dertobi123 1.2 # <i>mount /dev/sda2 /mnt/gentoo/boot</i>
344 swift 1.1 </pre>
345    
346     <note>
347     If you want your <path>/tmp</path> to reside on a separate partition, be sure to
348     change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
349     also holds for <path>/var/tmp</path>.
350     </note>
351    
352     <p>
353 swift 1.6 We will also have to mount the proc filesystem (a virtual interface with the
354     kernel) on <path>/proc</path>. But first we will need to place our files on the partitions.
355 swift 1.1 </p>
356    
357     <p>
358 swift 1.6 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
359 swift 1.1 Installation Files</uri>.
360     </p>
361    
362     </body>
363     </section>
364     </sections>

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