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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 swift 1.16 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
6 swift 1.1
7 swift 1.16 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-hppa-disk.xml,v 1.15 2005/02/20 12:38:07 swift Exp $ -->
8 swift 1.1
9     <sections>
10 swift 1.10
11 swift 1.16 <version>1.11</version>
12     <date>2005-06-10</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 swift 1.16 security and backups. You will definitely want to keep <path>/usr</path> big:
75     not only will it contain the majority of applications, the Portage tree alone
76     takes around 500 Mbyte excluding the various sources that are stored in it.
77    
78 swift 1.1 </p>
79    
80     <p>
81     As you can see, it very much depends on what you want to achieve. Separate
82     partitions or volumes have the following advantages:
83     </p>
84    
85     <ul>
86     <li>
87 neysx 1.3 You can choose the best performing filesystem for each partition or volume
88 swift 1.1 </li>
89     <li>
90     Your entire system cannot run out of free space if one defunct tool is
91     continuously writing files to a partition or volume
92     </li>
93     <li>
94     If necessary, file system checks are reduced in time, as multiple checks can
95     be done in parallel (although this advantage is more with multiple disks than
96     it is with multiple partitions)
97     </li>
98     <li>
99     Security can be enhanced by mounting some partitions or volumes read-only,
100     nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
101     </li>
102     </ul>
103    
104     <p>
105     However, multiple partitions have one big disadvantage: if not configured
106     properly, you might result in having a system with lots
107 swift 1.7 of free space on one partition and none on another. There is also a 15-partition
108 swift 1.8 limit for SCSI and SATA.
109 swift 1.1 </p>
110    
111     </body>
112     </subsection>
113     </section>
114     <section>
115     <title>Using fdisk on HPPA to Partition your Disk</title>
116     <body>
117    
118     <p>
119     Use <c>fdisk</c> to create the partitions you want:
120     </p>
121    
122     <pre caption="Partitioning the disk">
123     # <i>fdisk /dev/sda</i>
124     </pre>
125    
126     <p>
127 vapier 1.9 HPPA machines use the PC standard DOS partition tables. To create a new
128     DOS partition table, simply use the <c>o</c> command.
129     </p>
130    
131     <pre caption="Creating a DOS partition table">
132     # <i>fdisk /dev/sda</i>
133    
134     Command (m for help): <i>o</i>
135     Building a new DOS disklabel.
136     </pre>
137    
138     <p>
139     PALO (the HPPA bootloader) needs a special partition to work. You have
140 swift 1.13 to create a partition of at least 16MB at the beginning of your disk.
141 vapier 1.9 The partition type must be of type <e>f0</e> (Linux/PA-RISC boot).
142 swift 1.1 </p>
143    
144     <impo>
145     If you ignore this and continue without a special PALO partition, your system
146 swift 1.13 will stop loving you and fail to start. Also, if your disk is larger than 2GB,
147     make sure that the boot partition is in the first 2GB of your disk. PALO is
148     unable to read a kernel after the 2GB limit.
149 swift 1.1 </impo>
150    
151 vapier 1.9 <pre caption="A simple default partition schema">
152     # <i>cat /etc/fstab</i>
153     /dev/sda2 /boot ext3 noauto,noatime 1 1
154     /dev/sda3 none swap sw 0 0
155     /dev/sda4 / ext3 noatime 0 0
156    
157     # <i>fdisk /dev/sda</i>
158    
159     Command (m for help): <i>p</i>
160    
161     Disk /dev/sda: 4294 MB, 4294816768 bytes
162     133 heads, 62 sectors/track, 1017 cylinders
163     Units = cylinders of 8246 * 512 = 4221952 bytes
164    
165     Device Boot Start End Blocks Id System
166     /dev/sda1 1 8 32953 f0 Linux/PA-RISC boot
167     /dev/sda2 9 20 49476 83 Linux
168     /dev/sda3 21 70 206150 82 Linux swap
169     /dev/sda4 71 1017 3904481 83 Linux
170     </pre>
171    
172 swift 1.1 <p>
173     Now that your partitions are created, you can now continue with <uri
174     link="#filesystems">Creating Filesystems</uri>.
175     </p>
176    
177     </body>
178     </section>
179     <section id="filesystems">
180     <title>Creating Filesystems</title>
181     <subsection>
182     <title>Introduction</title>
183     <body>
184    
185     <p>
186     Now that your partitions are created, it is time to place a filesystem on them.
187     If you don't care about what filesystem to choose and are happy with what we use
188     as default in this handbook, continue with <uri
189     link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
190     Otherwise read on to learn about the available filesystems...
191     </p>
192    
193     </body>
194     </subsection>
195     <subsection>
196     <title>Filesystems?</title>
197     <body>
198    
199     <p>
200 dertobi123 1.5 Several filesystems are available. Ext2, ext3, XFS and reiserfs are found stable on
201 swift 1.1 the HPPA architecture. The others are very experimental.
202     </p>
203    
204     <p>
205     <b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata
206     journaling, which means that routine ext2 filesystem checks at startup time can
207     be quite time-consuming. There is now quite a selection of newer-generation
208     journaled filesystems that can be checked for consistency very quickly and are
209     thus generally preferred over their non-journaled counterparts. Journaled
210     filesystems prevent long delays when you boot your system and your filesystem
211     happens to be in an inconsistent state.
212     </p>
213    
214     <p>
215     <b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata
216     journaling for fast recovery in addition to other enhanced journaling modes like
217     full data and ordered data journaling. ext3 is a very good and reliable
218     filesystem. It has an additional hashed b-tree indexing option that enables
219     high performance in almost all situations. In short, ext3 is an excellent
220     filesystem.
221     </p>
222    
223     <p>
224     <b>ReiserFS</b> is a B*-tree based filesystem that has very good overall
225     performance and greatly outperforms both ext2 and ext3 when dealing with small
226     files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales
227     extremely well and has metadata journaling. As of kernel 2.4.18+, ReiserFS is
228     solid and usable as both general-purpose filesystem and for extreme cases such
229     as the creation of large filesystems, the use of many small files, very large
230     files and directories containing tens of thousands of files.
231     </p>
232    
233     <p>
234 neysx 1.4 <b>XFS</b> is a filesystem with metadata journaling which comes with a robust
235     feature-set and is optimized for scalability. We only recommend using this
236     filesystem on Linux systems with high-end SCSI and/or fibre channel storage and
237     an uninterruptible power supply. Because XFS aggressively caches in-transit data
238     in RAM, improperly designed programs (those that don't take proper precautions
239     when writing files to disk and there are quite a few of them) can lose a good
240     deal of data if the system goes down unexpectedly.
241 swift 1.1 </p>
242    
243     <p>
244     <b>JFS</b> is IBM's high-performance journaling filesystem. It has recently
245     become production-ready and there hasn't been a sufficient track record to
246     comment positively nor negatively on its general stability at this point.
247     </p>
248    
249     </body>
250     </subsection>
251     <subsection id="filesystems-apply">
252     <title>Applying a Filesystem to a Partition</title>
253     <body>
254    
255     <p>
256     To create a filesystem on a partition or volume, there are tools available for
257     each possible filesystem:
258     </p>
259    
260     <table>
261     <tr>
262     <th>Filesystem</th>
263     <th>Creation Command</th>
264     </tr>
265     <tr>
266     <ti>ext2</ti>
267     <ti><c>mke2fs</c></ti>
268     </tr>
269     <tr>
270     <ti>ext3</ti>
271     <ti><c>mke2fs -j</c></ti>
272     </tr>
273     <tr>
274     <ti>reiserfs</ti>
275     <ti><c>mkreiserfs</c></ti>
276     </tr>
277     <tr>
278     <ti>xfs</ti>
279     <ti><c>mkfs.xfs</c></ti>
280     </tr>
281     <tr>
282     <ti>jfs</ti>
283     <ti><c>mkfs.jfs</c></ti>
284     </tr>
285     </table>
286    
287     <p>
288 dertobi123 1.2 For instance, to have the boot partition (<path>/dev/sda2</path> in our
289     example) in ext2 and the root partition (<path>/dev/sda4</path> in our example)
290 swift 1.1 in ext3 (as in our example), you would use:
291     </p>
292    
293     <pre caption="Applying a filesystem on a partition">
294 dertobi123 1.2 # <i>mke2fs /dev/sda2</i>
295     # <i>mke2fs -j /dev/sda4</i>
296 swift 1.1 </pre>
297    
298     <p>
299     Now create the filesystems on your newly created partitions (or logical
300     volumes).
301     </p>
302    
303     </body>
304     </subsection>
305     <subsection>
306     <title>Activating the Swap Partition</title>
307     <body>
308    
309     <p>
310     <c>mkswap</c> is the command that is used to initialize swap partitions:
311     </p>
312    
313     <pre caption="Creating a Swap signature">
314 dertobi123 1.2 # <i>mkswap /dev/sda3</i>
315 swift 1.1 </pre>
316    
317     <p>
318     To activate the swap partition, use <c>swapon</c>:
319     </p>
320    
321     <pre caption="Activating the swap partition">
322 dertobi123 1.2 # <i>swapon /dev/sda3</i>
323 swift 1.1 </pre>
324    
325     <p>
326 swift 1.15 Create and activate the swap with the commands mentioned above.
327 swift 1.1 </p>
328    
329     </body>
330     </subsection>
331     </section>
332     <section>
333     <title>Mounting</title>
334     <body>
335    
336     <p>
337     Now that your partitions are initialized and are housing a filesystem, it is
338     time to mount those partitions. Use the <c>mount</c> command. Don't forget to
339     create the necessary mount directories for every partition you created. As an
340     example we mount the root and boot partition:
341     </p>
342    
343     <pre caption="Mounting partitions">
344 dertobi123 1.2 # <i>mount /dev/sda4 /mnt/gentoo</i>
345 swift 1.1 # <i>mkdir /mnt/gentoo/boot</i>
346 dertobi123 1.2 # <i>mount /dev/sda2 /mnt/gentoo/boot</i>
347 swift 1.1 </pre>
348    
349     <note>
350     If you want your <path>/tmp</path> to reside on a separate partition, be sure to
351     change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
352     also holds for <path>/var/tmp</path>.
353     </note>
354    
355     <p>
356 swift 1.6 We will also have to mount the proc filesystem (a virtual interface with the
357     kernel) on <path>/proc</path>. But first we will need to place our files on the partitions.
358 swift 1.1 </p>
359    
360     <p>
361 swift 1.6 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
362 swift 1.1 Installation Files</uri>.
363     </p>
364    
365     </body>
366     </section>
367     </sections>

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