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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 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-hppa-disk.xml,v 1.12 2004/11/20 22:23:30 neysx Exp $ -->
8
9 <sections>
10
11 <version>1.9</version>
12 <date>2004-09-30</date>
13
14 <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 You can choose the best performing filesystem for each partition or volume
85 </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 of free space on one partition and none on another. There is also a 15-partition
105 limit for SCSI and SATA.
106 </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 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 to create a partition of at least 16MB at the beginning of your disk.
138 The partition type must be of type <e>f0</e> (Linux/PA-RISC boot).
139 </p>
140
141 <impo>
142 If you ignore this and continue without a special PALO partition, your system
143 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 </impo>
147
148 <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 <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 Several filesystems are available. Ext2, ext3, XFS and reiserfs are found stable on
198 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 <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 </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 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 in ext3 (as in our example), you would use:
288 </p>
289
290 <pre caption="Applying a filesystem on a partition">
291 # <i>mke2fs /dev/sda2</i>
292 # <i>mke2fs -j /dev/sda4</i>
293 </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 # <i>mkswap /dev/sda3</i>
312 </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 # <i>swapon /dev/sda3</i>
320 </pre>
321
322 <p>
323 Create and activate the swap now.
324 </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 # <i>mount /dev/sda4 /mnt/gentoo</i>
342 # <i>mkdir /mnt/gentoo/boot</i>
343 # <i>mount /dev/sda2 /mnt/gentoo/boot</i>
344 </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 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 </p>
356
357 <p>
358 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
359 Installation Files</uri>.
360 </p>
361
362 </body>
363 </section>
364 </sections>

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