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fixing tree type confusion. spank whoever told me to add that ext3 stuff in the first place, and me for blindly adding it. all fixed now; also fixed reiserfs, since it's actually B+, not B*

1 <?xml version='1.0' encoding='UTF-8'?>
2 <!DOCTYPE sections SYSTEM "/dtd/book.dtd">
4 <!-- The content of this document is licensed under the CC-BY-SA license -->
5 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
7 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-ppc-disk.xml,v 1.42 2007/05/09 00:52:08 nightmorph Exp $ -->
9 <sections>
11 <version>8.2</version>
12 <date>2007-06-26</date>
14 <section>
15 <title>Introduction to Block Devices</title>
16 <subsection>
17 <title>Block Devices</title>
18 <body>
20 <p>
21 We'll start by taking 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>
28 <p>
29 To begin, we'll introduce <e>block devices</e>. The most common block device is
30 the one that represents the first IDE drive in a Linux system, namely
31 <path>/dev/hda</path>. If you are installing onto SCSI, FireWire, USB or SATA
32 drives, then your first hard drive would be <path>/dev/sda</path>. Additional
33 drives are enumerated by the next letter in the alphabet. As an example, the
34 third IDE disk could be found at <path>/dev/hdc</path>.
35 </p>
37 <p>
38 The block devices above represent an abstract interface to the disk. User
39 programs can use these block devices to interact with the disk without worrying
40 about whether the drives are IDE, SCSI or something else. The program can
41 simply address the storage on the disk as a bunch of contiguous,
42 randomly-accessible 512-byte blocks.
43 </p>
45 </body>
46 </subsection>
47 <subsection>
48 <title>Partitions</title>
49 <body>
51 <p>
52 Although it is theoretically possible to use a full disk to house your Linux
53 system, this is almost never done in practice. Instead, full disk block devices
54 are split up in smaller, more manageable block devices. On most systems,
55 these are called <e>partitions</e>.
56 </p>
58 </body>
59 </subsection>
60 </section>
61 <section>
62 <title>Designing a Partitioning Scheme</title>
63 <subsection>
64 <title>Default Partitioning Scheme</title>
65 <body>
67 <p>
68 If you are not interested in drawing up a partitioning scheme for your system,
69 you can use the partitioning scheme we use throughout this book. Choose the
70 filesystem layout that best matches the type of PowerPC system you are
71 installing on.
72 </p>
74 </body>
75 </subsection>
76 <subsection>
77 <title>Apple New World</title>
78 <body>
80 <p>
81 Apple New World machines are fairly straightforward to configure. The first
82 partition is always an <e>Apple Partition Map</e>. This partition keeps track
83 of the layout of the disk. You cannot remove this partition. The next
84 partition should always be a bootstrap partition. This partition contains a
85 small (800k) HFS filesystem that holds a copy of the bootloader Yaboot and its
86 configuration file. This partition is <e>not</e> the same as a
87 <path>/boot</path> partition as found on other architectures. After the boot
88 partition, the usual Linux filesystems are placed, according to the scheme
89 below. The swap partition is a temporary storage place for when your system
90 runs out of physical memory. The root partition will contain the filesystem
91 that Gentoo is installed on. If you wish to dual boot, the OSX partition
92 can go anywhere after the bootstrap partition to insure that yaboot starts
93 first.
94 </p>
96 <note>
97 There may be "Disk Driver" partitions on your disk such as
98 <path>Apple_Driver63</path>, <path>Apple_Driver_ATA</path>,
99 <path>Apple_FWDriver</path>, <path>Apple_Driver_IOKit</path>, and
100 <path>Apple_Patches</path>. These are used to boot MacOS, so if you have no
101 need for this, you can remove them by initializing the disk with mac-fdisk's
102 <c>i</c> option. This will completely erase the disk! If you are in doubt,
103 just let them be.
104 </note>
106 <note>
107 If you partitioned this disk with Apple's Disk Utility, there may be
108 128Mb spaces between partitions which Apple reserves for "future use". You
109 can safely remove these.
110 </note>
112 <table>
113 <tr>
114 <th>Partition</th>
115 <th>Size</th>
116 <th>Filesystem</th>
117 <th>Description</th>
118 </tr>
119 <tr>
120 <ti><path>/dev/hda1</path></ti>
121 <ti>32k</ti>
122 <ti>None</ti>
123 <ti>Apple Partition Map</ti>
124 </tr>
125 <tr>
126 <ti><path>/dev/hda2</path></ti>
127 <ti>800k</ti>
128 <ti>HFS</ti>
129 <ti>Apple Bootstrap</ti>
130 </tr>
131 <tr>
132 <ti><path>/dev/hda3</path></ti>
133 <ti>512Mb</ti>
134 <ti>Swap</ti>
135 <ti>Linux Swap</ti>
136 </tr>
137 <tr>
138 <ti><path>/dev/hda4</path></ti>
139 <ti>Rest of Disk</ti>
140 <ti>ext3, reiserfs, xfs</ti>
141 <ti>Linux Root</ti>
142 </tr>
143 </table>
145 </body>
146 </subsection>
147 <subsection>
148 <title>Apple Old World</title>
149 <body>
151 <p>
152 Apple Old World machines are a bit more complicated to configure. The first
153 partition is always an <e>Apple Partition Map</e>. This partition keeps track
154 of the layout of the disk. You cannot remove this partition. If you are using
155 BootX, the configuration below assumes that MacOS is installed on a seperate
156 disk. If this is not the case, there will be additional partitions for "Apple
157 Disk Drivers" such as <path>Apple_Driver63, Apple_Driver_ATA, Apple_FWDriver,
158 Apple_Driver_IOKit, Apple_Patches</path> and the MacOS install. If you are
159 using Quik, you will need to create a boot partition to hold the kernel, unlike
160 other Apple boot methods. After the boot partition, the usual Linux filesystems
161 are placed, according to the scheme below. The swap partition is a temporary
162 storage place for when your system runs out of physical memory. The root
163 partition will contain the filesystem that Gentoo is installed on.
164 </p>
166 <note>
167 If you are using an OldWorld machine, you will need to keep MacOS available.
168 The layout here assumes MacOS is installed on a separate drive.
169 </note>
171 <table>
172 <tr>
173 <th>Partition</th>
174 <th>Size</th>
175 <th>Filesystem</th>
176 <th>Description</th>
177 </tr>
178 <tr>
179 <ti><path>/dev/hda1</path></ti>
180 <ti>32k</ti>
181 <ti>None</ti>
182 <ti>Apple Partition Map</ti>
183 </tr>
184 <tr>
185 <ti><path>/dev/hda2</path></ti>
186 <ti>32Mb</ti>
187 <ti>ext2</ti>
188 <ti>Quik Boot Partition (quik only)</ti>
189 </tr>
190 <tr>
191 <ti><path>/dev/hda3</path></ti>
192 <ti>512Mb</ti>
193 <ti>Swap</ti>
194 <ti>Linux Swap</ti>
195 </tr>
196 <tr>
197 <ti><path>/dev/hda4</path></ti>
198 <ti>Rest of Disk</ti>
199 <ti>ext3, reiserfs, xfs</ti>
200 <ti>Linux Root</ti>
201 </tr>
202 </table>
204 </body>
205 </subsection>
206 <subsection>
207 <title>Pegasos</title>
208 <body>
210 <p>
211 The Pegasos partition layout is quite simple compared to the Apple layouts.
212 The first partition is a Boot Partition, which contains kernels to be booted,
213 along with an OpenFirmware script that presents a menu on boot. After the boot
214 partition, the usual Linux filesystems are placed, according to the scheme
215 below. The swap partition is a temporary storage place for when your system
216 runs out of physical memory. The root partition will contain the filesystem
217 that Gentoo is installed on.
218 </p>
220 <table>
221 <tr>
222 <th>Partition</th>
223 <th>Size</th>
224 <th>Filesystem</th>
225 <th>Description</th>
226 </tr>
227 <tr>
228 <ti><path>/dev/hda1</path></ti>
229 <ti>32Mb</ti>
230 <ti>affs1 or ext2</ti>
231 <ti>Boot Partition</ti>
232 </tr>
233 <tr>
234 <ti><path>/dev/hda2</path></ti>
235 <ti>512Mb</ti>
236 <ti>Swap</ti>
237 <ti>Linux Swap</ti>
238 </tr>
239 <tr>
240 <ti><path>/dev/hda3</path></ti>
241 <ti>Rest of Disk</ti>
242 <ti>ext3, reiserfs, xfs</ti>
243 <ti>Linux Root</ti>
244 </tr>
245 </table>
247 </body>
248 </subsection>
249 <subsection>
250 <title>IBM PReP (RS/6000)</title>
251 <body>
253 <p>
254 The IBM PowerPC Reference Platform (PReP) requires a small PReP boot partition
255 on the disk's first partition, followed by the swap and root partitions.
256 </p>
258 <table>
259 <tr>
260 <th>Partition</th>
261 <th>Size</th>
262 <th>Filesystem</th>
263 <th>Description</th>
264 </tr>
265 <tr>
266 <ti><path>/dev/hda1</path></ti>
267 <ti>800k</ti>
268 <ti>None</ti>
269 <ti>PReP Boot Partition (Type 0x41)</ti>
270 </tr>
271 <tr>
272 <ti><path>/dev/hda2</path></ti>
273 <ti>512Mb</ti>
274 <ti>Swap</ti>
275 <ti>Linux Swap (Type 0x82)</ti>
276 </tr>
277 <tr>
278 <ti><path>/dev/hda3</path></ti>
279 <ti>Rest of Disk</ti>
280 <ti>ext3, reiserfs, xfs</ti>
281 <ti>Linux Root (Type 0x83)</ti>
282 </tr>
283 </table>
285 <warn>
286 <c>parted</c> is able to resize partitions including HFS+. Unfortunately there
287 may be issues with resizing HFS+ journaled filesystems, so, for the best
288 results, switch off journaling in Mac OS X before resizing. Remember that any
289 resizing operation is dangerous, so attempt at your own risk! Be sure to always
290 have a backup of your data before resizing!
291 </warn>
293 <p>
294 If you are interested in knowing how big a partition should be, or even how many
295 partitions you need, read on. Otherwise continue now with
296 <uri link="#mac-fdisk"> Default: Using mac-fdisk (Apple) to Partition your Disk
297 </uri> or <uri link="#parted">Alternative: Using parted (IBM/Pegasos) to
298 Partition your Disk</uri>.
299 </p>
301 </body>
302 </subsection>
303 <subsection>
304 <title>How Many and How Big?</title>
305 <body>
307 <p>
308 The number of partitions is highly dependent on your environment. For instance,
309 if you have lots of users, you will most likely want to have your
310 <path>/home</path> separate as it increases security and makes backups easier.
311 If you are installing Gentoo to perform as a mailserver, your <path>/var</path>
312 should be separate as all received mail is stored in <path>/var</path>. A good
313 choice of filesystem will then maximise your performance. Game servers should
314 have a separate <path>/opt</path> as most game servers are installed there. The
315 reason is similar for <path>/home</path>: security and backups. Whatever layout
316 you chose, you will definitely want to keep <path>/usr</path> large: not only
317 will it contain the majority of applications, the Portage tree alone takes
318 more than 500Mb excluding the various sources that are stored in it.
319 </p>
321 <p>
322 As you can see, it very much depends on what you want to achieve. Separate
323 partitions or volumes have the following advantages:
324 </p>
326 <ul>
327 <li>
328 You can choose the best performing filesystem for each partition or volume
329 </li>
330 <li>
331 Your entire system cannot run out of free space if one defunct tool is
332 continuously writing files to a partition or volume
333 </li>
334 <li>
335 If necessary, file system checks are reduced in time, as multiple checks can
336 be done in parallel (although this advantage is more with multiple disks than
337 it is with multiple partitions)
338 </li>
339 <li>
340 Security can be enhanced by mounting some partitions or volumes read-only,
341 nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
342 </li>
343 </ul>
345 <p>
346 However, multiple partitions have one big disadvantage: if not configured
347 properly, you might result in having a system with lots of free space on one
348 partition and none on another. There is also a 15-partition limit for SCSI and
349 SATA.
350 </p>
352 </body>
353 </subsection>
354 </section>
355 <section id="mac-fdisk">
356 <title>Default: Using mac-fdisk (Apple) Partition your Disk</title>
357 <body>
359 <p>
360 At this point, create your partitions using <c>mac-fdisk</c>:
361 </p>
363 <pre caption="Starting mac-fdisk">
364 # <i>mac-fdisk /dev/hda</i>
365 </pre>
367 <p>
368 If you used Apple's Disk Utility to leave space for Linux, first delete the
369 partitions you have created previously to make room for your new install. Use
370 <c>d</c> in <c>mac-fdisk</c> to delete those partition(s). It will ask for the
371 partition number to delete. Usually the first partition on NewWorld machines
372 (Apple_partition_map) could not be deleted. If you would like to start with a
373 clean disk, you can simply initialize the disk by pressing <c>i</c>. This
374 will completely erase the disk, so use this with caution.
375 </p>
377 <p>
378 Second, create an <e>Apple_Bootstrap</e> partition by using <c>b</c>. It will
379 ask for what block you want to start. Enter the number of your first free
380 partition, followed by a <c>p</c>. For instance this is <c>2p</c>.
381 </p>
383 <note>
384 This partition is <e>not</e> a <path>/boot</path> partition. It is not used by
385 Linux at all; you don't have to place any filesystem on it and you should never
386 mount it. Apple users don't need an extra partition for <path>/boot</path>.
387 </note>
389 <p>
390 Now create a swap partition by pressing <c>c</c>. Again <c>mac-fdisk</c> will
391 ask for what block you want to start this partition from. As we used <c>2</c>
392 before to create the Apple_Bootstrap partition, you now have to enter
393 <c>3p</c>. When you're asked for the size, enter <c>512M</c> (or whatever size
394 you want -- a minimum of 512MB is recommended, but 2 times your physical memory
395 is the generally accepted size). When asked for a name, enter <c>swap</c>.
396 </p>
398 <p>
399 To create the root partition, enter <c>c</c>, followed by <c>4p</c> to select
400 from what block the root partition should start. When asked for the size, enter
401 <c>4p</c> again. <c>mac-fdisk</c> will interpret this as "Use all available
402 space". When asked for the name, enter <c>root</c>.
403 </p>
405 <p>
406 To finish up, write the partition to the disk using <c>w</c> and <c>q</c> to
407 quit <c>mac-fdisk</c>.
408 </p>
410 <note>
411 To make sure everything is ok, you should run <c>mac-fdisk -l</c> and check
412 whether all the partitions are there. If you don't see any of the partitions
413 you created, or the changes you made, you should reinitialize your partitions
414 by pressing "i" in mac-fdisk. Note that this will recreate the partition map
415 and thus remove all your partitions.
416 </note>
418 <p>
419 Now that your partitions are created, you can continue with
420 <uri link="#filesystems">Creating Filesystems</uri>.
421 </p>
423 </body>
424 </section>
425 <section id="parted">
426 <title>Using parted to Partition your Disk (Pegasos and RS/6000)</title>
427 <body>
429 <p>
430 <c>parted</c>, the Partition Editor, can now handle HFS+ partitions used by
431 Mac OS and Mac OS X. With this tool you can resize your Mac-partitions and
432 create space for your Linux partitions. Nevertheless, the example below
433 describes partitioning for Pegasos machines only.
434 </p>
436 <p>
437 To begin let's fire up <c>parted</c>:
438 </p>
440 <pre caption="Starting parted">
441 # <i>parted /dev/hda</i>
442 </pre>
444 <p>
445 If the drive is unpartitioned, run <c>mklabel amiga</c> to create a new
446 disklabel for the drive.
447 </p>
449 <p>
450 You can type <c>print</c> at any time in parted to display the current partition
451 table. If at any time you change your mind or made a mistake you can press
452 <c>Ctrl-c</c> to abort parted.
453 </p>
455 <p>
456 If you intend to also install MorphOS on your Pegasos create an affs1 filesystem
457 at the start of the drive. 32MB should be more than enough to store the MorphOS
458 kernel. If you have a Pegasos I or intend to use any filesystem besides ext2 or
459 ext3, you will also have to store your Linux kernel on this partition (the
460 Pegasos II can only boot from ext2/ext3 or affs1 partitions). To create the
461 partition run <c>mkpart primary affs1 START END</c> where <c>START</c> and
462 <c>END</c> should be replaced with the megabyte range (e.g. <c>0 32</c>) which
463 creates a 32 MB partition starting at 0MB and ending at 32MB. If you chose to
464 create an ext2 or ext3 partition instead, substitute ext2 or ext3 for affs1 in
465 the mkpart command.
466 </p>
468 <p>
469 You will need to create two partitions for Linux, one root filesystem and one
470 swap partition. Run <c>mkpart primary START END</c> to create each partition,
471 replacing <c>START</c> and <c>END</c> with the desired megabyte boundries.
472 </p>
474 <p>
475 It is generally recommended that you create a swap partition that is two times
476 bigger than the amount of RAM in your computer, but at least 512Mb is
477 recommended. To create the swap partition, run
478 <c>mkpart primary linux-swap START END</c> with START and END again denoting
479 the partition boundries.
480 </p>
482 <p>
483 When you are done in parted simply type <c>quit</c>.
484 </p>
486 </body>
487 </section>
488 <section id="filesystems">
489 <title>Creating Filesystems</title>
490 <subsection>
491 <title>Introduction</title>
492 <body>
494 <p>
495 Now that your partitions are created, it is time to place a filesystem on them.
496 If you're not sure which filesystems to choose and are happy with our defaults,
497 continue with
498 <uri link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
499 Otherwise, read on to learn about the available filesystems.
500 </p>
502 </body>
503 </subsection>
504 <subsection>
505 <title>Filesystems?</title>
506 <body>
508 <p>
509 Several filesystems are available for use on the PowerPC architecture including
510 ext2, ext3, ReiserFS and XFS, each with their strengths and faults.
511 </p>
513 <p>
514 <b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata
515 journaling, which means that routine ext2 filesystem checks at startup time can
516 be quite time-consuming. There is now quite a selection of journaled
517 filesystems that can be checked for consistency very quickly and are thus
518 generally preferred over their non-journaled counterparts.
519 </p>
521 <p>
522 <b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata
523 journaling for fast recovery in addition to other enhanced journaling modes like
524 full data and ordered data journaling. It uses an HTree index that enables high
525 performance in almost all situations. In short, ext3 is a very good and reliable
526 filesystem.
527 </p>
529 <p>
530 <b>ReiserFS</b> is a B+tree-based filesystem that has very good overall
531 performance and greatly outperforms both ext2 and ext3 when dealing with small
532 files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales
533 extremely well and has metadata journaling. ReiserFS is solid and usable as
534 both general-purpose filesystem and for extreme cases such as the creation of
535 large filesystems, very large files and directories containing tens of
536 thousands of small files.
537 </p>
539 <p>
540 <b>XFS</b> is a filesystem with metadata journaling which comes with a robust
541 feature-set and is optimized for scalability. We only recommend using this
542 filesystem on Linux systems with high-end SCSI and/or fibre channel storage and
543 an uninterruptible power supply. Because XFS aggressively caches in-transit data
544 in RAM, improperly designed programs (those that don't take proper precautions
545 when writing files to disk and there are quite a few of them) can lose a good
546 deal of data if the system goes down unexpectedly.
547 </p>
549 </body>
550 </subsection>
551 <subsection>
552 <title>Activating the Swap Partition</title>
553 <body>
555 <p>
556 <c>mkswap</c> is the command that is used to initialize swap partitions:
557 </p>
559 <pre caption="Creating a swap signature">
560 # <i>mkswap /dev/hda3</i>
561 </pre>
563 <p>
564 To activate the swap partition, use <c>swapon</c>:
565 </p>
567 <pre caption="Activating the swap partition">
568 # <i>swapon /dev/hda3</i>
569 </pre>
571 <p>
572 Create and activate the swap now before creating other filesystems.
573 </p>
575 </body>
576 </subsection>
577 <subsection id="filesystems-apply">
578 <title>Applying a Filesystem to a Partition</title>
579 <body>
581 <p>
582 To create a filesystem on a partition or volume, there are tools available for
583 each possible filesystem:
584 </p>
586 <table>
587 <tr>
588 <th>Filesystem</th>
589 <th>Creation Command</th>
590 </tr>
591 <tr>
592 <ti>ext2</ti>
593 <ti><c>mke2fs</c></ti>
594 </tr>
595 <tr>
596 <ti>ext3</ti>
597 <ti><c>mke2fs -j</c></ti>
598 </tr>
599 <tr>
600 <ti>reiserfs</ti>
601 <ti><c>mkreiserfs</c></ti>
602 </tr>
603 <tr>
604 <ti>xfs</ti>
605 <ti><c>mkfs.xfs</c></ti>
606 </tr>
607 </table>
609 <p>
610 For instance, to make an ext3 filesystem on the root partition
611 (<path>/dev/hda4</path> in our example), you would use:
612 </p>
614 <pre caption="Applying a filesystem on a partition">
615 # <i>mke2fs -j /dev/hda4</i>
616 </pre>
618 <p>
619 Now create the filesystems on your newly created partitions (or logical
620 volumes).
621 </p>
623 <note>
624 On the PegasosII your partition which holds the kernel must be ext2, ext3 or
625 affs1. NewWorld machines can boot from any of ext2, ext3, XFS, ReiserFS or
626 even HFS/HFS+ filesystems. On OldWorld machines booting with BootX, the kernel
627 must be placed on an HFS partition, but this will be completed when you
628 configure your bootloader.
629 </note>
631 </body>
632 </subsection>
633 </section>
634 <section>
635 <title>Mounting</title>
636 <body>
638 <p>
639 Now that your partitions are initialized and are housing a filesystem, it is
640 time to mount those partitions. Use the <c>mount</c> command. As an example we
641 mount the root partition:
642 </p>
644 <pre caption="Mounting partitions">
645 # <i>mount /dev/hda4 /mnt/gentoo</i>
646 </pre>
648 <note>
649 If you want your <path>/tmp</path> to reside on a separate partition, be sure to
650 change its permissions after mounting and unpacking with
651 <c>chmod 1777 /mnt/gentoo/tmp</c>. This is also true for <path>/var/tmp</path>.
652 </note>
654 <p>
655 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
656 Installation Files</uri>.
657 </p>
659 </body>
660 </section>
661 </sections>

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