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Revision 1.29 - (show annotations) (download) (as text)
Mon Oct 17 19:51:45 2011 UTC (3 years, 2 months ago) by swift
Branch: MAIN
Changes since 1.28: +13 -7 lines
File MIME type: application/xml
Enhancing information on downsides wrt multiple partitions.

This hopefully also clears up some of the confusion that is surrounding
separate /usr partitions. Yes, it now mentions that an initramfs might be
needed in that case.

And no, we do not "recommend" a separate /usr partition, nor do we
"not recommend" it.

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/2.5 -->
6
7 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-hppa-disk.xml,v 1.28 2011/09/17 12:16:09 swift Exp $ -->
8
9 <sections>
10
11 <version>12</version>
12 <date>2011-10-17</date>
13
14 <section>
15 <title>Introduction to Block Devices</title>
16
17 <subsection>
18 <include href="hb-install-blockdevices.xml"/>
19 </subsection>
20
21 <subsection>
22 <title>Partitions and Slices</title>
23 <body>
24
25 <p>
26 Although it is theoretically possible to use a full disk to house your Linux
27 system, this is almost never done in practice. Instead, full disk block devices
28 are split up in smaller, more manageable block devices. On most systems, these
29 are called <e>partitions</e>. Other architectures use a similar technique,
30 called <e>slices</e>.
31 </p>
32
33 </body>
34 </subsection>
35 </section>
36 <section>
37 <title>Designing a Partitioning Scheme</title>
38 <subsection>
39 <title>How Many and How Big?</title>
40 <body>
41
42 <p>
43 The number of partitions is highly dependent on your environment. For instance,
44 if you have lots of users, you will most likely want to have your
45 <path>/home</path> separate as it increases security and makes backups easier.
46 If you are installing Gentoo to perform as a mailserver, your <path>/var</path>
47 should be separate as all mails are stored inside <path>/var</path>. A good
48 choice of filesystem will then maximise your performance. Gameservers will have
49 a separate <path>/opt</path> as most gaming servers are installed there. The
50 reason is similar for <path>/home</path>: security and backups. You will
51 definitely want to keep <path>/usr</path> big: not only will it contain the
52 majority of applications, the Portage tree alone takes around 500 Mbyte
53 excluding the various sources that are stored in it.
54 </p>
55
56 <p>
57 As you can see, it very much depends on what you want to achieve. Separate
58 partitions or volumes have the following advantages:
59 </p>
60
61 <ul>
62 <li>
63 You can choose the best performing filesystem for each partition or volume
64 </li>
65 <li>
66 Your entire system cannot run out of free space if one defunct tool is
67 continuously writing files to a partition or volume
68 </li>
69 <li>
70 If necessary, file system checks are reduced in time, as multiple checks can
71 be done in parallel (although this advantage is more with multiple disks than
72 it is with multiple partitions)
73 </li>
74 <li>
75 Security can be enhanced by mounting some partitions or volumes read-only,
76 nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
77 </li>
78 </ul>
79
80 <p>
81 However, multiple partitions have disadvantages as well. If not configured
82 properly, you will have a system with lots of free space on one partition and
83 none on another. Another nuisance is that separate partitions - especially
84 for important mountpoints like <path>/usr</path> or <path>/var</path> - often
85 require the administrator to boot with an initramfs to mount the partition
86 before other boot scripts start. This isn't always the case though, so YMMV.
87 </p>
88
89 <p>
90 There is also a 15-partition limit for SCSI and SATA.
91 </p>
92
93 </body>
94 </subsection>
95 </section>
96 <section>
97 <title>Using fdisk on HPPA to Partition your Disk</title>
98 <body>
99
100 <p>
101 Use <c>fdisk</c> to create the partitions you want:
102 </p>
103
104 <pre caption="Partitioning the disk">
105 # <i>fdisk /dev/sda</i>
106 </pre>
107
108 <p>
109 HPPA machines use the PC standard DOS partition tables. To create a new
110 DOS partition table, simply use the <c>o</c> command.
111 </p>
112
113 <pre caption="Creating a DOS partition table">
114 # <i>fdisk /dev/sda</i>
115
116 Command (m for help): <i>o</i>
117 Building a new DOS disklabel.
118 </pre>
119
120 <p>
121 PALO (the HPPA bootloader) needs a special partition to work. You have
122 to create a partition of at least 16MB at the beginning of your disk.
123 The partition type must be of type <e>f0</e> (Linux/PA-RISC boot).
124 </p>
125
126 <impo>
127 If you ignore this and continue without a special PALO partition, your system
128 will stop loving you and fail to start. Also, if your disk is larger than 2GB,
129 make sure that the boot partition is in the first 2GB of your disk. PALO is
130 unable to read a kernel after the 2GB limit.
131 </impo>
132
133 <pre caption="A simple default partition scheme">
134 # <i>cat /etc/fstab</i>
135 /dev/sda2 /boot ext3 noauto,noatime 1 1
136 /dev/sda3 none swap sw 0 0
137 /dev/sda4 / ext3 noatime 0 0
138
139 # <i>fdisk /dev/sda</i>
140
141 Command (m for help): <i>p</i>
142
143 Disk /dev/sda: 4294 MB, 4294816768 bytes
144 133 heads, 62 sectors/track, 1017 cylinders
145 Units = cylinders of 8246 * 512 = 4221952 bytes
146
147 Device Boot Start End Blocks Id System
148 /dev/sda1 1 8 32953 f0 Linux/PA-RISC boot
149 /dev/sda2 9 20 49476 83 Linux
150 /dev/sda3 21 70 206150 82 Linux swap
151 /dev/sda4 71 1017 3904481 83 Linux
152 </pre>
153
154 <p>
155 Now that your partitions are created, you can continue with <uri
156 link="#filesystems">Creating Filesystems</uri>.
157 </p>
158
159 </body>
160 </section>
161 <section id="filesystems">
162 <title>Creating Filesystems</title>
163 <subsection>
164 <title>Introduction</title>
165 <body>
166
167 <p>
168 Now that your partitions are created, it is time to place a filesystem on them.
169 If you don't care about what filesystem to choose and are happy with what we use
170 as default in this handbook, continue with <uri
171 link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
172 Otherwise read on to learn about the available filesystems...
173 </p>
174
175 </body>
176 </subsection>
177
178 <subsection>
179 <include href="hb-install-filesystems.xml"/>
180 </subsection>
181
182 <subsection id="filesystems-apply">
183 <title>Applying a Filesystem to a Partition</title>
184 <body>
185
186 <p>
187 To create a filesystem on a partition or volume, there are tools available for
188 each possible filesystem:
189 </p>
190
191 <table>
192 <tr>
193 <th>Filesystem</th>
194 <th>Creation Command</th>
195 </tr>
196 <tr>
197 <ti>ext2</ti>
198 <ti><c>mkfs.ext2</c></ti>
199 </tr>
200 <tr>
201 <ti>ext3</ti>
202 <ti><c>mkfs.ext3</c></ti>
203 </tr>
204 <tr>
205 <ti>ext4</ti>
206 <ti><c>mkfs.ext4</c></ti>
207 </tr>
208 <tr>
209 <ti>reiserfs</ti>
210 <ti><c>mkreiserfs</c></ti>
211 </tr>
212 <tr>
213 <ti>xfs</ti>
214 <ti><c>mkfs.xfs</c></ti>
215 </tr>
216 <tr>
217 <ti>jfs</ti>
218 <ti><c>mkfs.jfs</c></ti>
219 </tr>
220 </table>
221
222 <p>
223 For instance, to have the boot partition (<path>/dev/sda2</path> in our
224 example) in ext2 and the root partition (<path>/dev/sda4</path> in our example)
225 in ext3 (as in our example), you would use:
226 </p>
227
228 <pre caption="Applying a filesystem on a partition">
229 # <i>mkfs.ext2 /dev/sda2</i>
230 # <i>mkfs.ext3 /dev/sda4</i>
231 </pre>
232
233 <p>
234 Now create the filesystems on your newly created partitions (or logical
235 volumes).
236 </p>
237
238 </body>
239 </subsection>
240 <subsection>
241 <title>Activating the Swap Partition</title>
242 <body>
243
244 <p>
245 <c>mkswap</c> is the command that is used to initialize swap partitions:
246 </p>
247
248 <pre caption="Creating a Swap signature">
249 # <i>mkswap /dev/sda3</i>
250 </pre>
251
252 <p>
253 To activate the swap partition, use <c>swapon</c>:
254 </p>
255
256 <pre caption="Activating the swap partition">
257 # <i>swapon /dev/sda3</i>
258 </pre>
259
260 <p>
261 Create and activate the swap with the commands mentioned above.
262 </p>
263
264 </body>
265 </subsection>
266 </section>
267 <section>
268 <title>Mounting</title>
269 <body>
270
271 <p>
272 Now that your partitions are initialized and are housing a filesystem, it is
273 time to mount those partitions. Use the <c>mount</c> command. Don't forget to
274 create the necessary mount directories for every partition you created. As an
275 example we mount the root and boot partition:
276 </p>
277
278 <pre caption="Mounting partitions">
279 # <i>mount /dev/sda4 /mnt/gentoo</i>
280 # <i>mkdir /mnt/gentoo/boot</i>
281 # <i>mount /dev/sda2 /mnt/gentoo/boot</i>
282 </pre>
283
284 <note>
285 If you want your <path>/tmp</path> to reside on a separate partition, be sure
286 to change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>.
287 This also holds for <path>/var/tmp</path>.
288 </note>
289
290 <p>
291 We will also have to mount the proc filesystem (a virtual interface with the
292 kernel) on <path>/proc</path>. But first we will need to place our files on the
293 partitions.
294 </p>
295
296 <p>
297 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
298 Installation Files</uri>.
299 </p>
300
301 </body>
302 </section>
303 </sections>

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