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Mon Oct 17 19:51:45 2011 UTC (2 years, 10 months ago) by swift
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Changes since 1.49: +13 -7 lines
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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-ppc-disk.xml,v 1.49 2010/07/21 01:28:29 nightmorph Exp $ -->
8
9 <sections>
10
11 <abstract>
12 To be able to install Gentoo, you must create the necessary partitions.
13 This chapter describes how to partition a disk for future usage.
14 </abstract>
15
16 <version>11</version>
17 <date>2011-10-17</date>
18
19 <section>
20 <title>Introduction to Block Devices</title>
21
22 <subsection>
23 <include href="hb-install-blockdevices.xml"/>
24 </subsection>
25
26 <subsection>
27 <title>Partitions</title>
28 <body>
29
30 <p>
31 Although it is theoretically possible to use a full disk to house your Linux
32 system, this is almost never done in practice. Instead, full disk block devices
33 are split up in smaller, more manageable block devices. On most systems,
34 these are called <e>partitions</e>.
35 </p>
36
37 </body>
38 </subsection>
39 </section>
40 <section>
41 <title>Designing a Partitioning Scheme</title>
42 <subsection>
43 <title>Default Partitioning Scheme</title>
44 <body>
45
46 <p>
47 If you are not interested in drawing up a partitioning scheme for your system,
48 you can use the partitioning scheme we use throughout this book. Choose the
49 filesystem layout that best matches the type of PowerPC system you are
50 installing on.
51 </p>
52
53 </body>
54 </subsection>
55 <subsection>
56 <title>Apple New World</title>
57 <body>
58
59 <p>
60 Apple New World machines are fairly straightforward to configure. The first
61 partition is always an <e>Apple Partition Map</e>. This partition keeps track of
62 the layout of the disk. You cannot remove this partition. The next partition
63 should always be a bootstrap partition. This partition contains a small (800k)
64 HFS filesystem that holds a copy of the bootloader Yaboot and its configuration
65 file. This partition is <e>not</e> the same as a <path>/boot</path> partition as
66 found on other architectures. After the boot partition, the usual Linux
67 filesystems are placed, according to the scheme below. The swap partition is a
68 temporary storage place for when your system runs out of physical memory. The
69 root partition will contain the filesystem that Gentoo is installed on. If you
70 wish to dual boot, the OSX partition can go anywhere after the bootstrap
71 partition to insure that yaboot starts first.
72 </p>
73
74 <note>
75 There may be "Disk Driver" partitions on your disk such as
76 <path>Apple_Driver63</path>, <path>Apple_Driver_ATA</path>,
77 <path>Apple_FWDriver</path>, <path>Apple_Driver_IOKit</path>, and
78 <path>Apple_Patches</path>. These are used to boot MacOS, so if you have no need
79 for this, you can remove them by initializing the disk with <c>mac-fdisk</c>'s
80 <c>i</c> option. This will completely erase the disk! If you are in doubt, just
81 let them be.
82 </note>
83
84 <note>
85 If you partitioned this disk with Apple's Disk Utility, there may be
86 128Mb spaces between partitions which Apple reserves for "future use". You
87 can safely remove these.
88 </note>
89
90 <table>
91 <tr>
92 <th>Partition</th>
93 <th>Size</th>
94 <th>Filesystem</th>
95 <th>Description</th>
96 </tr>
97 <tr>
98 <ti><path>/dev/sda1</path></ti>
99 <ti>32k</ti>
100 <ti>None</ti>
101 <ti>Apple Partition Map</ti>
102 </tr>
103 <tr>
104 <ti><path>/dev/sda2</path></ti>
105 <ti>800k</ti>
106 <ti>HFS</ti>
107 <ti>Apple Bootstrap</ti>
108 </tr>
109 <tr>
110 <ti><path>/dev/sda3</path></ti>
111 <ti>512Mb</ti>
112 <ti>Swap</ti>
113 <ti>Linux Swap</ti>
114 </tr>
115 <tr>
116 <ti><path>/dev/sda4</path></ti>
117 <ti>Rest of Disk</ti>
118 <ti>ext3, reiserfs, xfs</ti>
119 <ti>Linux Root</ti>
120 </tr>
121 </table>
122
123 </body>
124 </subsection>
125 <subsection>
126 <title>Apple Old World</title>
127 <body>
128
129 <p>
130 Apple Old World machines are a bit more complicated to configure. The first
131 partition is always an <e>Apple Partition Map</e>. This partition keeps track
132 of the layout of the disk. You cannot remove this partition. If you are using
133 BootX, the configuration below assumes that MacOS is installed on a seperate
134 disk. If this is not the case, there will be additional partitions for "Apple
135 Disk Drivers" such as <path>Apple_Driver63, Apple_Driver_ATA, Apple_FWDriver,
136 Apple_Driver_IOKit, Apple_Patches</path> and the MacOS install. If you are
137 using Quik, you will need to create a boot partition to hold the kernel, unlike
138 other Apple boot methods. After the boot partition, the usual Linux filesystems
139 are placed, according to the scheme below. The swap partition is a temporary
140 storage place for when your system runs out of physical memory. The root
141 partition will contain the filesystem that Gentoo is installed on.
142 </p>
143
144 <note>
145 If you are using an OldWorld machine, you will need to keep MacOS available.
146 The layout here assumes MacOS is installed on a separate drive.
147 </note>
148
149 <table>
150 <tr>
151 <th>Partition</th>
152 <th>Size</th>
153 <th>Filesystem</th>
154 <th>Description</th>
155 </tr>
156 <tr>
157 <ti><path>/dev/sda1</path></ti>
158 <ti>32k</ti>
159 <ti>None</ti>
160 <ti>Apple Partition Map</ti>
161 </tr>
162 <tr>
163 <ti><path>/dev/sda2</path></ti>
164 <ti>32Mb</ti>
165 <ti>ext2</ti>
166 <ti>Quik Boot Partition (quik only)</ti>
167 </tr>
168 <tr>
169 <ti><path>/dev/sda3</path></ti>
170 <ti>512Mb</ti>
171 <ti>Swap</ti>
172 <ti>Linux Swap</ti>
173 </tr>
174 <tr>
175 <ti><path>/dev/sda4</path></ti>
176 <ti>Rest of Disk</ti>
177 <ti>ext3, reiserfs, xfs</ti>
178 <ti>Linux Root</ti>
179 </tr>
180 </table>
181
182 </body>
183 </subsection>
184 <subsection>
185 <title>Pegasos</title>
186 <body>
187
188 <p>
189 The Pegasos partition layout is quite simple compared to the Apple layouts.
190 The first partition is a Boot Partition, which contains kernels to be booted,
191 along with an Open Firmware script that presents a menu on boot. After the boot
192 partition, the usual Linux filesystems are placed, according to the scheme
193 below. The swap partition is a temporary storage place for when your system
194 runs out of physical memory. The root partition will contain the filesystem
195 that Gentoo is installed on.
196 </p>
197
198 <table>
199 <tr>
200 <th>Partition</th>
201 <th>Size</th>
202 <th>Filesystem</th>
203 <th>Description</th>
204 </tr>
205 <tr>
206 <ti><path>/dev/sda1</path></ti>
207 <ti>32Mb</ti>
208 <ti>affs1 or ext2</ti>
209 <ti>Boot Partition</ti>
210 </tr>
211 <tr>
212 <ti><path>/dev/sda2</path></ti>
213 <ti>512Mb</ti>
214 <ti>Swap</ti>
215 <ti>Linux Swap</ti>
216 </tr>
217 <tr>
218 <ti><path>/dev/sda3</path></ti>
219 <ti>Rest of Disk</ti>
220 <ti>ext3, reiserfs, xfs</ti>
221 <ti>Linux Root</ti>
222 </tr>
223 </table>
224
225 </body>
226 </subsection>
227 <subsection>
228 <title>IBM PReP (RS/6000)</title>
229 <body>
230
231 <p>
232 The IBM PowerPC Reference Platform (PReP) requires a small PReP boot partition
233 on the disk's first partition, followed by the swap and root partitions.
234 </p>
235
236 <table>
237 <tr>
238 <th>Partition</th>
239 <th>Size</th>
240 <th>Filesystem</th>
241 <th>Description</th>
242 </tr>
243 <tr>
244 <ti><path>/dev/sda1</path></ti>
245 <ti>800k</ti>
246 <ti>None</ti>
247 <ti>PReP Boot Partition (Type 0x41)</ti>
248 </tr>
249 <tr>
250 <ti><path>/dev/sda2</path></ti>
251 <ti>512Mb</ti>
252 <ti>Swap</ti>
253 <ti>Linux Swap (Type 0x82)</ti>
254 </tr>
255 <tr>
256 <ti><path>/dev/sda3</path></ti>
257 <ti>Rest of Disk</ti>
258 <ti>ext3, reiserfs, xfs</ti>
259 <ti>Linux Root (Type 0x83)</ti>
260 </tr>
261 </table>
262
263 <warn>
264 <c>parted</c> is able to resize partitions including HFS+. Unfortunately there
265 may be issues with resizing HFS+ journaled filesystems, so, for the best
266 results, switch off journaling in Mac OS X before resizing. Remember that any
267 resizing operation is dangerous, so attempt at your own risk! Be sure to always
268 have a backup of your data before resizing!
269 </warn>
270
271 <p>
272 If you are interested in knowing how big a partition should be, or even how many
273 partitions you need, read on. Otherwise continue now with
274 <uri link="#mac-fdisk"> Default: Using mac-fdisk (Apple) to Partition your Disk
275 </uri> or <uri link="#parted">Alternative: Using parted (IBM/Pegasos) to
276 Partition your Disk</uri>.
277 </p>
278
279 </body>
280 </subsection>
281 <subsection>
282 <title>How Many and How Big?</title>
283 <body>
284
285 <p>
286 The number of partitions is highly dependent on your environment. For instance,
287 if you have lots of users, you will most likely want to have your
288 <path>/home</path> separate as it increases security and makes backups easier.
289 If you are installing Gentoo to perform as a mailserver, your <path>/var</path>
290 should be separate as all received mail is stored in <path>/var</path>. A good
291 choice of filesystem will then maximise your performance. Game servers should
292 have a separate <path>/opt</path> as most game servers are installed there. The
293 reason is similar for <path>/home</path>: security and backups. Whatever layout
294 you chose, you will definitely want to keep <path>/usr</path> large: not only
295 will it contain the majority of applications, the Portage tree alone takes
296 more than 500Mb excluding the various sources that are stored in it.
297 </p>
298
299 <p>
300 As you can see, it very much depends on what you want to achieve. Separate
301 partitions or volumes have the following advantages:
302 </p>
303
304 <ul>
305 <li>
306 You can choose the best performing filesystem for each partition or volume
307 </li>
308 <li>
309 Your entire system cannot run out of free space if one defunct tool is
310 continuously writing files to a partition or volume
311 </li>
312 <li>
313 If necessary, file system checks are reduced in time, as multiple checks can
314 be done in parallel (although this advantage is more with multiple disks than
315 it is with multiple partitions)
316 </li>
317 <li>
318 Security can be enhanced by mounting some partitions or volumes read-only,
319 nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
320 </li>
321 </ul>
322
323 <p>
324 However, multiple partitions have disadvantages as well. If not configured
325 properly, you will have a system with lots of free space on one partition and
326 none on another. Another nuisance is that separate partitions - especially
327 for important mountpoints like <path>/usr</path> or <path>/var</path> - often
328 require the administrator to boot with an initramfs to mount the partition
329 before other boot scripts start. This isn't always the case though, so YMMV.
330 </p>
331
332 <p>
333 There is also a 15-partition limit for SCSI and SATA.
334 </p>
335
336 </body>
337 </subsection>
338 </section>
339 <section id="mac-fdisk">
340 <title>Default: Using mac-fdisk (Apple) Partition your Disk</title>
341 <body>
342
343 <p>
344 At this point, create your partitions using <c>mac-fdisk</c>:
345 </p>
346
347 <pre caption="Starting mac-fdisk">
348 # <i>mac-fdisk /dev/sda</i>
349 </pre>
350
351 <p>
352 If you used Apple's Disk Utility to leave space for Linux, first delete the
353 partitions you have created previously to make room for your new install. Use
354 <c>d</c> in <c>mac-fdisk</c> to delete those partition(s). It will ask for the
355 partition number to delete. Usually the first partition on NewWorld machines
356 (Apple_partition_map) cannot be deleted. If you would like to start with a
357 clean disk, you can simply initialize the disk by pressing <c>i</c>. This
358 will completely erase the disk, so use this with caution.
359 </p>
360
361 <p>
362 Second, create an <e>Apple_Bootstrap</e> partition by using <c>b</c>. It will
363 ask for what block you want to start. Enter the number of your first free
364 partition, followed by a <c>p</c>. For instance this is <c>2p</c>.
365 </p>
366
367 <note>
368 This partition is <e>not</e> a <path>/boot</path> partition. It is not used by
369 Linux at all; you don't have to place any filesystem on it and you should never
370 mount it. Apple users don't need an extra partition for <path>/boot</path>.
371 </note>
372
373 <p>
374 Now create a swap partition by pressing <c>c</c>. Again <c>mac-fdisk</c> will
375 ask for what block you want to start this partition from. As we used <c>2</c>
376 before to create the Apple_Bootstrap partition, you now have to enter
377 <c>3p</c>. When you're asked for the size, enter <c>512M</c> (or whatever size
378 you want -- a minimum of 512MB is recommended, but 2 times your physical memory
379 is the generally accepted size). When asked for a name, enter <c>swap</c>.
380 </p>
381
382 <p>
383 To create the root partition, enter <c>c</c>, followed by <c>4p</c> to select
384 from what block the root partition should start. When asked for the size, enter
385 <c>4p</c> again. <c>mac-fdisk</c> will interpret this as "Use all available
386 space". When asked for the name, enter <c>root</c>.
387 </p>
388
389 <p>
390 To finish up, write the partition to the disk using <c>w</c> and <c>q</c> to
391 quit <c>mac-fdisk</c>.
392 </p>
393
394 <note>
395 To make sure everything is ok, you should run <c>mac-fdisk -l</c> and check
396 whether all the partitions are there. If you don't see any of the partitions you
397 created, or the changes you made, you should reinitialize your partitions by
398 pressing <c>i</c> in <c>mac-fdisk</c>. Note that this will recreate the
399 partition map and thus remove all your partitions.
400 </note>
401
402 <p>
403 Now that your partitions are created, you can continue with
404 <uri link="#filesystems">Creating Filesystems</uri>.
405 </p>
406
407 </body>
408 </section>
409 <section id="parted">
410 <title>Using parted to Partition your Disk (Pegasos and RS/6000)</title>
411 <body>
412
413 <p>
414 <c>parted</c>, the Partition Editor, can now handle HFS+ partitions used by
415 Mac OS and Mac OS X. With this tool you can resize your Mac partitions and
416 create space for your Linux partitions. Nevertheless, the example below
417 describes partitioning for Pegasos machines only.
418 </p>
419
420 <p>
421 To begin let's fire up <c>parted</c>:
422 </p>
423
424 <pre caption="Starting parted">
425 # <i>parted /dev/sda</i>
426 </pre>
427
428 <p>
429 If the drive is unpartitioned, run <c>mklabel amiga</c> to create a new
430 disklabel for the drive.
431 </p>
432
433 <p>
434 You can type <c>print</c> at any time in parted to display the current partition
435 table. If at any time you change your mind or made a mistake you can press
436 <c>Ctrl-c</c> to abort <c>parted</c>.
437 </p>
438
439 <p>
440 If you intend to also install MorphOS on your Pegasos create an affs1 filesystem
441 at the start of the drive. 32MB should be more than enough to store the MorphOS
442 kernel. If you have a Pegasos I or intend to use any filesystem besides ext2 or
443 ext3, you will also have to store your Linux kernel on this partition (the
444 Pegasos II can only boot from ext2/ext3 or affs1 partitions). To create the
445 partition run <c>mkpart primary affs1 START END</c> where <c>START</c> and
446 <c>END</c> should be replaced with the megabyte range (e.g. <c>0 32</c>) which
447 creates a 32 MB partition starting at 0MB and ending at 32MB. If you chose to
448 create an ext2 or ext3 partition instead, substitute ext2 or ext3 for affs1 in
449 the <c>mkpart</c> command.
450 </p>
451
452 <p>
453 You will need to create two partitions for Linux, one root filesystem and one
454 swap partition. Run <c>mkpart primary START END</c> to create each partition,
455 replacing <c>START</c> and <c>END</c> with the desired megabyte boundries.
456 </p>
457
458 <p>
459 It is generally recommended that you create a swap partition that is two times
460 bigger than the amount of RAM in your computer, but at least 512Mb is
461 recommended. To create the swap partition, run
462 <c>mkpart primary linux-swap START END</c> with START and END again denoting
463 the partition boundries.
464 </p>
465
466 <p>
467 When you are done in <c>parted</c> simply type <c>quit</c>.
468 </p>
469
470 </body>
471 </section>
472 <section id="filesystems">
473 <title>Creating Filesystems</title>
474 <subsection>
475 <title>Introduction</title>
476 <body>
477
478 <p>
479 Now that your partitions are created, it is time to place a filesystem on them.
480 If you're not sure which filesystems to choose and are happy with our defaults,
481 continue with
482 <uri link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
483 Otherwise, read on to learn about the available filesystems.
484 </p>
485
486 </body>
487 </subsection>
488
489 <subsection>
490 <include href="hb-install-filesystems.xml"/>
491 </subsection>
492
493 <subsection>
494 <title>Activating the Swap Partition</title>
495 <body>
496
497 <p>
498 <c>mkswap</c> is the command that is used to initialize swap partitions:
499 </p>
500
501 <pre caption="Creating a swap signature">
502 # <i>mkswap /dev/sda3</i>
503 </pre>
504
505 <p>
506 To activate the swap partition, use <c>swapon</c>:
507 </p>
508
509 <pre caption="Activating the swap partition">
510 # <i>swapon /dev/sda3</i>
511 </pre>
512
513 <p>
514 Create and activate the swap now before creating other filesystems.
515 </p>
516
517 </body>
518 </subsection>
519 <subsection id="filesystems-apply">
520 <title>Applying a Filesystem to a Partition</title>
521 <body>
522
523 <p>
524 To create a filesystem on a partition or volume, there are tools available for
525 each possible filesystem:
526 </p>
527
528 <table>
529 <tr>
530 <th>Filesystem</th>
531 <th>Creation Command</th>
532 </tr>
533 <tr>
534 <ti>ext2</ti>
535 <ti><c>mke2fs</c></ti>
536 </tr>
537 <tr>
538 <ti>ext3</ti>
539 <ti><c>mke2fs -j</c></ti>
540 </tr>
541 <tr>
542 <ti>reiserfs</ti>
543 <ti><c>mkreiserfs</c></ti>
544 </tr>
545 <tr>
546 <ti>xfs</ti>
547 <ti><c>mkfs.xfs</c></ti>
548 </tr>
549 </table>
550
551 <p>
552 For instance, to make an ext3 filesystem on the root partition
553 (<path>/dev/sda4</path> in our example), you would use:
554 </p>
555
556 <pre caption="Applying a filesystem on a partition">
557 # <i>mke2fs -j /dev/sda4</i>
558 </pre>
559
560 <p>
561 Now create the filesystems on your newly created partitions (or logical
562 volumes).
563 </p>
564
565 <impo>
566 If you choose to use ReiserFS for <path>/</path>, do not change its default
567 block size if you will also be using <c>yaboot</c> as your bootloader, as
568 explained in <uri link="?part=1&amp;chap=10">Configuring the Bootloader</uri>.
569 </impo>
570
571 <note>
572 On the PegasosII your partition which holds the kernel must be ext2, ext3 or
573 affs1. NewWorld machines can boot from any of ext2, ext3, XFS, ReiserFS or
574 even HFS/HFS+ filesystems. On OldWorld machines booting with BootX, the kernel
575 must be placed on an HFS partition, but this will be completed when you
576 configure your bootloader.
577 </note>
578
579 </body>
580 </subsection>
581 </section>
582 <section>
583 <title>Mounting</title>
584 <body>
585
586 <p>
587 Now that your partitions are initialized and are housing a filesystem, it is
588 time to mount those partitions. Use the <c>mount</c> command. As an example we
589 mount the root partition:
590 </p>
591
592 <pre caption="Mounting partitions">
593 # <i>mount /dev/sda4 /mnt/gentoo</i>
594 </pre>
595
596 <note>
597 If you want your <path>/tmp</path> to reside on a separate partition, be sure to
598 change its permissions after mounting and unpacking with
599 <c>chmod 1777 /mnt/gentoo/tmp</c>. This is also true for <path>/var/tmp</path>.
600 </note>
601
602 <p>
603 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
604 Installation Files</uri>.
605 </p>
606
607 </body>
608 </section>
609 </sections>

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