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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-ppc-disk.xml,v 1.19 2004/11/02 11:52:49 sejo Exp $ -->
8
9 <sections>
10
11 <version>1.19</version>
12 <date>November 2, 2004</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 IDE drive in a Linux system, namely
31 <path>/dev/hda</path>. If your system uses SCSI drives, then your first hard
32 drive would be <path>/dev/sda</path>.
33 </p>
34
35 <p>
36 The block devices above represent an abstract interface to the disk. User
37 programs can use these block devices to interact with your disk without worrying
38 about whether your drives are IDE, SCSI or something else. The program can
39 simply address the storage on the disk as a bunch of contiguous,
40 randomly-accessible 512-byte blocks.
41 </p>
42
43 </body>
44 </subsection>
45 <subsection>
46 <title>Partitions and Slices</title>
47 <body>
48
49 <p>
50 Although it is theoretically possible to use a full disk to house your Linux
51 system, this is almost never done in practice. Instead, full disk block devices
52 are split up in smaller, more manageable block devices. On most systems,
53 these are called <e>partitions</e>. Other architectures use a similar technique,
54 called <e>slices</e>.
55 </p>
56
57 </body>
58 </subsection>
59 </section>
60 <section>
61 <title>Designing a Partitioning Scheme</title>
62 <subsection>
63 <title>Default Partitioning Scheme</title>
64 <body>
65
66 <p>
67 If you are not interested in drawing up a partitioning scheme for your system,
68 you can use the partitioning scheme we use throughout this book:
69 </p>
70
71 <table>
72 <tr>
73 <th>Partition NewWorld</th>
74 <th>Partition OldWorld</th>
75 <th>Partition Pegasos</th>
76 <th>Filesystem</th>
77 <th>Size</th>
78 <th>Description</th>
79 </tr>
80 <tr>
81 <ti><path>/dev/hda1</path></ti>
82 <ti>/dev/hda1</ti>
83 <ti>(Not applicable)</ti>
84 <ti>(Partition Map)</ti>
85 <ti>32k</ti>
86 <ti>Apple_partition_map</ti>
87 </tr>
88 <tr>
89 <ti><path>/dev/hda2</path></ti>
90 <ti>(Not needed)</ti>
91 <ti>(Not applicable)</ti>
92 <ti>(bootstrap)</ti>
93 <ti>800k</ti>
94 <ti>Apple_Bootstrap</ti>
95 </tr>
96 <tr>
97 <ti><path>/dev/hda3</path></ti>
98 <ti><path>/dev/hda2</path></ti>
99 <ti><path>/dev/hda1</path></ti>
100 <ti>(swap)</ti>
101 <ti>512M</ti>
102 <ti>Swap partition</ti>
103 </tr>
104 <tr>
105 <ti><path>/dev/hda4</path></ti>
106 <ti><path>/dev/hda3</path></ti>
107 <ti><path>/dev/hda2</path></ti>
108 <ti>ext3</ti>
109 <ti>Rest of the disk</ti>
110 <ti>Root partition</ti>
111 </tr>
112 </table>
113 <note>
114 There are some partitions named like this: <path>Apple_Driver43,
115 Apple_Driver_ATA, Apple_FWDriver, Apple_Driver_IOKit,
116 Apple_Patches</path>. If you are not planning to use MacOS 9 you can
117 delete them, because MacOS X and Linux don't need them.
118 You might have to use parted in order to delete them, as mac-fdisk can't delete them yet.
119 </note>
120 <p>
121 If you are interested in knowing how big a partition should be, or even how
122 many partitions you need, read on. Otherwise continue now with
123 <uri link="#fdisk">Default: Using mac-fdisk (Apple/IBM) to Partition your
124 Disk</uri> or <uri link="#parted">Alternative: Using parted (especially Pegasos) to
125 Partition your Disk</uri>.
126 </p>
127
128 </body>
129 </subsection>
130 <subsection>
131 <title>How Many and How Big?</title>
132 <body>
133
134 <p>
135 The number of partitions is highly dependent on your environment. For instance,
136 if you have lots of users, you will most likely want to have your
137 <path>/home</path> separate as it increases security and makes backups easier.
138 If you are installing Gentoo to perform as a mailserver, your
139 <path>/var</path> should be separate as all mails are stored inside
140 <path>/var</path>. A good choice of filesystem will then maximise your
141 performance. Gameservers will have a separate <path>/opt</path> as most gaming
142 servers are installed there. The reason is similar for <path>/home</path>:
143 security and backups.
144 </p>
145
146 <p>
147 As you can see, it very much depends on what you want to achieve. Separate
148 partitions or volumes have the following advantages:
149 </p>
150
151 <ul>
152 <li>
153 You can choose the best performing filesystem for each partition or volume
154 </li>
155 <li>
156 Your entire system cannot run out of free space if one defunct tool is
157 continuously writing files to a partition or volume
158 </li>
159 <li>
160 If necessary, file system checks are reduced in time, as multiple checks can
161 be done in parallel (although this advantage is more with multiple disks than
162 it is with multiple partitions)
163 </li>
164 <li>
165 Security can be enhanced by mounting some partitions or volumes read-only,
166 nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
167 </li>
168 </ul>
169
170 <p>
171 However, multiple partitions have one big disadvantage: if not configured
172 properly, you might result in having a system with lots
173 of free space on one partition and none on another. There is also a 15-partition
174 limit for SCSI and SATA.
175 </p>
176
177 </body>
178 </subsection>
179 </section>
180 <section id="fdisk">
181 <title>Default: Using mac-fdisk (Apple/IBM) Partition your Disk</title>
182 <body>
183
184 <p>
185 At this point, create your partitions using <c>mac-fdisk</c>:
186 </p>
187
188 <pre caption="Starting mac-fdisk">
189 # <i>mac-fdisk /dev/hda</i>
190 </pre>
191
192 <p>
193 First delete the partitions you have cleared previously to make room for your
194 Linux partitions. Use <c>d</c> in <c>mac-fdisk</c> to delete those partition(s).
195 It will ask for the partition number to delete.
196 </p>
197
198 <p>
199 Second, create an <e>Apple_Bootstrap</e> partition by using <c>b</c>. It will
200 ask for what block you want to start. Enter the number of your first free
201 partition, followed by a <c>p</c>. For instance this is <c>1p</c>.
202 </p>
203
204 <note>
205 This partition is <e>not</e> a "boot" partition. It is not used by Linux at all;
206 you don't have to place any filesystem on it and you should never mount it. PPC
207 users don't need a an extra partition for <path>/boot</path>.
208 </note>
209
210 <p>
211 Now create a swap partition by pressing <c>c</c>. Again <c>mac-fdisk</c> will
212 ask for what block you want to start this partition from. As we used <c>1</c>
213 before to create the Apple_Bootstrap partition, you now have to enter
214 <c>2p</c>. When you're asked for the size, enter <c>512M</c> (or whatever size
215 you want -- 512MB is recommended though). When asked for a name, enter <c>swap</c>
216 (mandatory).
217 </p>
218
219 <p>
220 To create the root partition, enter <c>c</c>, followed by <c>3p</c> to select
221 from what block the root partition should start. When asked for the size, enter
222 <c>3p</c> again. <c>mac-fdisk</c> will interpret this as "Use all available
223 space". When asked for the name, enter <c>root</c> (mandatory).
224 </p>
225
226 <p>
227 To finish up, write the partition to the disk using <c>w</c> and <c>q</c> to
228 quit <c>mac-fdisk</c>.
229 </p>
230
231 <note>
232 To make sure everything is ok, you should run mac-fdisk once more and check whether all the partitions are there.
233 If you don't see any of the partitions you created, or the changes you made, you should reinitialize your partitions by pressing "i" in mac-fdisk.
234 Note that this will recreate the partition map and thus remove all your partitions.
235 </note>
236
237 <p>
238 Now that your partitions are created, you can now continue with <uri
239 link="#filesystems">Creating Filesystems</uri>.
240 </p>
241
242 </body>
243 </section>
244 <section id="parted">
245 <title>Using parted (especially Pegasos) to Partition your Disk</title>
246 <body>
247
248 <p>
249 <c>parted</c>, the Partition Editor, can now handle HFS+ partitions used by
250 Mac OS and Mac OS X. With this tool you can shrink your Mac-partitions and
251 create space for your Linux partitions. Nevertheless, the example below
252 describes partitioning for Pegasos machines only.
253 </p>
254
255 <p>
256 To begin let's fire up <c>parted</c>:
257 </p>
258
259 <pre caption="Starting parted">
260 # <i>parted /dev/hda</i>
261 </pre>
262
263 <p>
264 If the drive is unpartitioned, run <c>mklabel amiga</c> to create a new
265 disklabel for the drive.
266 </p>
267
268 <p>
269 You can type <c>print</c> at any time in parted to display the current partition
270 table. Your changes aren't saved until you quit the application; if at any time
271 you change your mind or made a mistake you can press <c>Ctrl-c</c> to abort
272 parted.
273 </p>
274
275 <p>
276 If you intend to also install MorphOS on your Pegasos create an affs1 filesystem
277 named "BI0" (BI zero) at the start of the drive. 50MB should be more than enough
278 to store the MorphOS kernel. If you have a Pegasos I or intend to use reiserfs or
279 xfs, you will also have to store your Linux kernel on this partition (the
280 Pegasos II can boot from ext2/ext3 drives). To create the partition run
281 <c>mkpart primary affs1 START END</c> where <c>START</c> and <c>END</c> should
282 be replaced with the megabyte range (f.i. <c>5 55</c> creates a 50 MB partition
283 starting at 5MB and ending at 55MB.
284 </p>
285
286 <p>
287 You need to create two partitions for Linux, one root filesystem for all your
288 program files etc, and one swap partition. To create the root filesystem you
289 must first decide which filesystem to use. Possible options are ext2, ext3,
290 reiserfs and xfs. Unless you know what you are doing, use ext3. Run
291 <c>mkpart primary ext3 START END</c> to create an ext3 partition. Again, replace
292 <c>START</c> and <c>END</c> with the megabyte start and stop marks for the
293 partition.
294 </p>
295
296 <p>
297 It is generally recommended that you create a swap partition the same size as
298 the amount of RAM in your computer times two. You will probably get away with a
299 smaller swap partition unless you intend to run a lot of applications at the
300 same time (although at least 512MB is recommended). To create the swap
301 partition, run <c>mkpart primary linux-swap START END</c>.
302 </p>
303
304 <p>
305 Write down the partition minor numbers as they are required during the
306 installation process. To dislay the minor numbers run <c>print</c>. Your drives
307 are accessed as <path>/dev/hdaX</path> where X is replaced with the minor number
308 of the partition.
309 </p>
310
311 <p>
312 When you are done in parted simply run <c>quit</c>.
313 </p>
314
315 </body>
316 </section>
317 <section id="filesystems">
318 <title>Creating Filesystems</title>
319 <subsection>
320 <title>Introduction</title>
321 <body>
322
323 <p>
324 Now that your partitions are created, it is time to place a filesystem on them.
325 If you don't care about what filesystem to choose and are happy with what we use
326 as default in this handbook, continue with <uri
327 link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
328 Otherwise read on to learn about the available filesystems...
329 </p>
330
331 </body>
332 </subsection>
333 <subsection>
334 <title>Filesystems?</title>
335 <body>
336
337 <p>
338 Several filesystems are available. ext2, ext3, reiserfs and xfs are found stable
339 on the PPC architecture. jfs is unsupported.
340 </p>
341
342 <p>
343 <b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata
344 journaling, which means that routine ext2 filesystem checks at startup time can
345 be quite time-consuming. There is now quite a selection of newer-generation
346 journaled filesystems that can be checked for consistency very quickly and are
347 thus generally preferred over their non-journaled counterparts. Journaled
348 filesystems prevent long delays when you boot your system and your filesystem
349 happens to be in an inconsistent state.
350 </p>
351
352 <p>
353 <b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata
354 journaling for fast recovery in addition to other enhanced journaling modes like
355 full data and ordered data journaling. ext3 is a very good and reliable
356 filesystem. It has an additional hashed b-tree indexing option that enables
357 high performance in almost all situations. In short, ext3 is an excellent
358 filesystem.
359 </p>
360
361 <p>
362 <b>ReiserFS</b> is a B*-tree based filesystem that has very good overall
363 performance and greatly outperforms both ext2 and ext3 when dealing with small
364 files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales
365 extremely well and has metadata journaling. As of kernel 2.4.18+, ReiserFS is
366 solid and usable as both general-purpose filesystem and for extreme cases such
367 as the creation of large filesystems, the use of many small files, very large
368 files and directories containing tens of thousands of files.
369 </p>
370
371 <p>
372 <b>XFS</b> is a filesystem with metadata journaling which comes with a robust
373 feature-set and is optimized for scalability. We only recommend using this
374 filesystem on Linux systems with high-end SCSI and/or fibre channel storage and
375 an uninterruptible power supply. Because XFS aggressively caches in-transit data
376 in RAM, improperly designed programs (those that don't take proper precautions
377 when writing files to disk and there are quite a few of them) can lose a good
378 deal of data if the system goes down unexpectedly.
379 </p>
380
381 </body>
382 </subsection>
383 <subsection id="filesystems-apply">
384 <title>Applying a Filesystem to a Partition</title>
385 <body>
386
387 <p>
388 To create a filesystem on a partition or volume, there are tools available for
389 each possible filesystem:
390 </p>
391
392 <table>
393 <tr>
394 <th>Filesystem</th>
395 <th>Creation Command</th>
396 </tr>
397 <tr>
398 <ti>ext2</ti>
399 <ti><c>mke2fs</c></ti>
400 </tr>
401 <tr>
402 <ti>ext3</ti>
403 <ti><c>mke2fs -j</c></ti>
404 </tr>
405 <tr>
406 <ti>reiserfs</ti>
407 <ti><c>mkreiserfs</c></ti>
408 </tr>
409 <tr>
410 <ti>xfs</ti>
411 <ti><c>mkfs.xfs</c></ti>
412 </tr>
413 </table>
414
415 <p>
416 For instance, to have the root partition (<path>/dev/hda3</path> in our example)
417 in ext3 (as in our example), you would use:
418 </p>
419
420 <pre caption="Applying a filesystem on a partition">
421 # <i>mke2fs -j /dev/hda3</i>
422 </pre>
423
424 <p>
425 Now create the filesystems on your newly created partitions (or logical
426 volumes).
427 </p>
428
429 <note>
430 Be sure that the partition which will host your kernel (the
431 <path>/boot</path>-path) must be ext2 or ext3. The bootloader can only handle
432 this filesystem.
433 </note>
434
435 </body>
436 </subsection>
437 <subsection>
438 <title>Activating the Swap Partition</title>
439 <body>
440
441 <p>
442 <c>mkswap</c> is the command that is used to initialize swap partitions:
443 </p>
444
445 <pre caption="Creating a Swap signature">
446 # <i>mkswap /dev/hda2</i>
447 </pre>
448
449 <p>
450 To activate the swap partition, use <c>swapon</c>:
451 </p>
452
453 <pre caption="Activating the swap partition">
454 # <i>swapon /dev/hda2</i>
455 </pre>
456
457 <p>
458 Create and activate the swap now.
459 </p>
460
461 </body>
462 </subsection>
463 </section>
464 <section>
465 <title>Mounting</title>
466 <body>
467
468 <p>
469 Now that your partitions are initialized and are housing a filesystem, it is
470 time to mount those partitions. Use the <c>mount</c> command. Don't forget to
471 create the necessary mount directories for every partition you created. As an
472 example we create a mount-point and mount the root and boot partition:
473 </p>
474
475 <pre caption="Mounting partitions">
476 # <i>mkdir /mnt/gentoo</i>
477 # <i>mount /dev/hda3 /mnt/gentoo</i>
478 </pre>
479
480 <note>
481 If you want your <path>/tmp</path> to reside on a separate partition, be sure to
482 change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
483 also holds for <path>/var/tmp</path>.
484 </note>
485
486 <p>
487 Finally we have to create the <path>/dev</path> files in our new home, which is
488 needed during the bootloader installation. This could be done by "bind"-mapping
489 the <path>/dev</path>-filesystem from the LiveCD:
490 </p>
491
492 <pre caption="Bind-mounting the /dev-filesystem">
493 # <i>mkdir /mnt/gentoo/dev</i>
494 # <i>mount -o bind /dev /mnt/gentoo/dev</i>
495 </pre>
496
497 <p>
498 We will also have to mount the proc filesystem (a virtual interface with the
499 kernel) on <path>/proc</path>. But first we will need to place our files on the partitions.
500 </p>
501
502 <p>
503 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
504 Installation Files</uri>.
505 </p>
506
507 </body>
508 </section>
509 </sections>

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