/[gentoo]/xml/htdocs/doc/en/handbook/hb-install-arm-disk.xml
Gentoo

Contents of /xml/htdocs/doc/en/handbook/hb-install-arm-disk.xml

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.4 - (show annotations) (download) (as text)
Fri Feb 16 13:45:39 2007 UTC (7 years, 6 months ago) by neysx
Branch: MAIN
Changes since 1.3: +4 -4 lines
File MIME type: application/xml
Removing -O dir_index was not clever.
It'll have to be removed for 2007.0 though.

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-arm-disk.xml,v 1.3 2006/11/02 20:49:38 nightmorph Exp $ -->
8
9 <sections>
10
11 <version>4.2</version>
12 <date>2007-02-16</date>
13
14 <!-- TODO: Add section about MTD and such -->
15
16 <section>
17 <title>Introduction to Block Devices</title>
18 <subsection>
19 <title>Block Devices</title>
20 <body>
21
22 <p>
23 We'll take a good look at disk-oriented aspects of Gentoo Linux
24 and Linux in general, including Linux filesystems, partitions and block devices.
25 Then, once you're familiar with the ins and outs of disks and filesystems,
26 you'll be guided through the process of setting up partitions and filesystems
27 for your Gentoo Linux installation.
28 </p>
29
30 <p>
31 To begin, we'll introduce <e>block devices</e>. The most famous block device is
32 probably the one that represents the first IDE drive in a Linux system, namely
33 <path>/dev/hda</path>. If your system uses SCSI or SATA drives, then your
34 first hard drive would be <path>/dev/sda</path>.
35 </p>
36
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 your disk without worrying
40 about whether your 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>
44
45 </body>
46 </subsection>
47 <subsection>
48 <title>Partitions</title>
49 <body>
50
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 <keyval id="arch"/>
55 systems, these are called <e>partitions</e>.
56 </p>
57
58 <p>
59 Partitions are divided in three types:
60 <e>primary</e>, <e>extended</e> and <e>logical</e>.
61 </p>
62
63 <p>
64 A <e>primary</e> partition is a partition which has its information stored in
65 the MBR (master boot record). As an MBR is very small (512 bytes) only four
66 primary partitions can be defined (for instance, <path>/dev/hda1</path> to
67 <path>/dev/hda4</path>).
68 </p>
69
70 <p>
71 An <e>extended</e> partition is a special primary partition (meaning the
72 extended partition must be one of the four possible primary partitions) which
73 contains more partitions. Such a partition didn't exist originally, but as
74 four partitions were too few, it was brought to life to extend the formatting
75 scheme without losing backward compatibility.
76 </p>
77
78 <p>
79 A <e>logical</e> partition is a partition inside the extended partition. Their
80 definitions aren't placed inside the MBR, but are declared inside the extended
81 partition.
82 </p>
83
84 </body>
85 </subsection>
86 </section>
87 <section>
88 <title>Designing a Partitioning Scheme</title>
89 <subsection>
90 <title>Default Partitioning Scheme</title>
91 <body>
92
93 <warn>
94 The NetWinder firmware, NeTTrom, can only read ext2 partitions realiably so you
95 must have a separate ext2 boot partition.
96 </warn>
97
98 <p>
99 If you are not interested in drawing up a partitioning scheme for your system,
100 you can use the partitioning scheme we use throughout this book:
101 </p>
102
103 <table>
104 <tr>
105 <th>Partition</th>
106 <th>Filesystem</th>
107 <th>Size</th>
108 <th>Description</th>
109 </tr>
110 <tr>
111 <ti><path>/dev/hda1</path></ti>
112 <ti>ext2</ti>
113 <ti>32M</ti>
114 <ti>Boot partition</ti>
115 </tr>
116 <tr>
117 <ti><path>/dev/hda2</path></ti>
118 <ti>(swap)</ti>
119 <ti>512M</ti>
120 <ti>Swap partition</ti>
121 </tr>
122 <tr>
123 <ti><path>/dev/hda3</path></ti>
124 <ti>ext3</ti>
125 <ti>Rest of the disk</ti>
126 <ti>Root partition</ti>
127 </tr>
128 </table>
129
130 <p>
131 If you are interested in knowing how big a partition should be, or even how
132 many partitions you need, read on. Otherwise continue now with partitioning
133 your disk by reading <uri link="#fdisk">Using fdisk to Partition your
134 Disk</uri>.
135 </p>
136
137 </body>
138 </subsection>
139 <subsection>
140 <title>How Many and How Big?</title>
141 <body>
142
143 <p>
144 The number of partitions is highly dependent on your environment. For instance,
145 if you have lots of users, you will most likely want to have your
146 <path>/home</path> separate as it increases security and makes backups easier.
147 If you are installing Gentoo to perform as a mailserver, your
148 <path>/var</path> should be separate as all mails are stored inside
149 <path>/var</path>. A good choice of filesystem will then maximise your
150 performance. Gameservers will have a separate <path>/opt</path> as most gaming
151 servers are installed there. The reason is similar for <path>/home</path>:
152 security and backups. You will definitely want to keep <path>/usr</path> big:
153 not only will it contain the majority of applications, the Portage tree alone
154 takes around 500 Mbyte excluding the various sources that are stored in it.
155 </p>
156
157 <p>
158 As you can see, it very much depends on what you want to achieve. Separate
159 partitions or volumes have the following advantages:
160 </p>
161
162 <ul>
163 <li>
164 You can choose the best performing filesystem for each partition or volume
165 </li>
166 <li>
167 Your entire system cannot run out of free space if one defunct tool is
168 continuously writing files to a partition or volume
169 </li>
170 <li>
171 If necessary, file system checks are reduced in time, as multiple checks can
172 be done in parallel (although this advantage is more with multiple disks than
173 it is with multiple partitions)
174 </li>
175 <li>
176 Security can be enhanced by mounting some partitions or volumes read-only,
177 nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
178 </li>
179 </ul>
180
181 <p>
182 However, multiple partitions have one big disadvantage: if not configured
183 properly, you might result in having a system with lots of free space on one
184 partition and none on another. There is also a 15-partition limit for SCSI and
185 SATA.
186 </p>
187
188 <p>
189 As an example partitioning, we show you one for a 20GB disk, used as a
190 demonstration laptop (containing webserver, mailserver, gnome, ...):
191 </p>
192
193 <pre caption="Filesystem usage example">
194 $ <i>df -h</i>
195 Filesystem Type Size Used Avail Use% Mounted on
196 /dev/hda5 ext3 509M 132M 351M 28% /
197 /dev/hda2 ext3 5.0G 3.0G 1.8G 63% /home
198 /dev/hda7 ext3 7.9G 6.2G 1.3G 83% /usr
199 /dev/hda8 ext3 1011M 483M 477M 51% /opt
200 /dev/hda9 ext3 2.0G 607M 1.3G 32% /var
201 /dev/hda1 ext2 51M 17M 31M 36% /boot
202 /dev/hda6 swap 516M 12M 504M 2% &lt;not mounted&gt;
203 <comment>(Unpartitioned space for future usage: 2 GB)</comment>
204 </pre>
205
206 <p>
207 <path>/usr</path> is rather full (83% used) here, but once
208 all software is installed, <path>/usr</path> doesn't tend to grow that much.
209 Although allocating a few gigabytes of disk space for <path>/var</path> may
210 seem excessive, remember that Portage uses this partition by default for
211 compiling packages. If you want to keep <path>/var</path> at a more reasonable
212 size, such as 1GB, you will need to alter your <c>PORTAGE_TMPDIR</c> variable
213 in <path>/etc/make.conf</path> to point to the partition with enough free space
214 for compiling extremely large packages such as OpenOffice.
215 </p>
216
217 </body>
218 </subsection>
219 </section>
220 <section id="fdisk">
221 <title>Using fdisk to Partition your Disk</title>
222 <subsection>
223 <body>
224
225 <p>
226 The following parts explain how to create the example partition layout
227 described previously, namely:
228 </p>
229
230 <table>
231 <tr>
232 <th>Partition</th>
233 <th>Description</th>
234 </tr>
235 <tr>
236 <ti><path>/dev/hda1</path></ti>
237 <ti>Boot partition</ti>
238 </tr>
239 <tr>
240 <ti><path>/dev/hda2</path></ti>
241 <ti>Swap partition</ti>
242 </tr>
243 <tr>
244 <ti><path>/dev/hda3</path></ti>
245 <ti>Root partition</ti>
246 </tr>
247 </table>
248
249 <p>
250 Change your partition layout according to your own preference.
251 </p>
252
253 </body>
254 </subsection>
255 <subsection>
256 <title>Viewing the Current Partition Layout</title>
257 <body>
258
259 <p>
260 <c>fdisk</c> is a popular and powerful tool to split your disk into partitions.
261 Fire up <c>fdisk</c> on your disk (in our example, we use
262 <path>/dev/hda</path>):
263 </p>
264
265 <pre caption="Starting fdisk">
266 # <i>fdisk /dev/hda</i>
267 </pre>
268
269 <p>
270 Once in <c>fdisk</c>, you'll be greeted with a prompt that looks like this:
271 </p>
272
273 <pre caption="fdisk prompt">
274 Command (m for help):
275 </pre>
276
277 <p>
278 Type <c>p</c> to display your disk's current partition configuration:
279 </p>
280
281 <pre caption="An example partition configuration">
282 Command (m for help): <i>p</i>
283
284 Disk /dev/hda: 240 heads, 63 sectors, 2184 cylinders
285 Units = cylinders of 15120 * 512 bytes
286
287 Device Boot Start End Blocks Id System
288 /dev/hda1 1 14 105808+ 83 Linux
289 /dev/hda2 15 49 264600 82 Linux swap
290 /dev/hda3 50 70 158760 83 Linux
291 /dev/hda4 71 2184 15981840 5 Extended
292 /dev/hda5 71 209 1050808+ 83 Linux
293 /dev/hda6 210 348 1050808+ 83 Linux
294 /dev/hda7 349 626 2101648+ 83 Linux
295 /dev/hda8 627 904 2101648+ 83 Linux
296 /dev/hda9 905 2184 9676768+ 83 Linux
297
298 Command (m for help):
299 </pre>
300
301 <p>
302 This particular disk is configured to house seven Linux filesystems (each with
303 a corresponding partition listed as "Linux") as well as a swap partition
304 (listed as "Linux swap").
305 </p>
306
307 </body>
308 </subsection>
309 <subsection>
310 <title>Removing all Partitions</title>
311 <body>
312
313 <p>
314 We will first remove all existing partitions from the disk. Type <c>d</c> to
315 delete a partition. For instance, to delete an existing <path>/dev/hda1</path>:
316 </p>
317
318 <pre caption="Deleting a partition">
319 Command (m for help): <i>d</i>
320 Partition number (1-4): <i>1</i>
321 </pre>
322
323 <p>
324 The partition has been scheduled for deletion. It will no longer show up if you
325 type <c>p</c>, but it will not be erased until your changes have been saved. If
326 you made a mistake and want to abort without saving your changes, type <c>q</c>
327 immediately and hit enter and your partition will not be deleted.
328 </p>
329
330 <p>
331 Now, assuming that you do indeed want to wipe out all the partitions on your
332 system, repeatedly type <c>p</c> to print out a partition listing and then type
333 <c>d</c> and the number of the partition to delete it. Eventually, you'll end
334 up with a partition table with nothing in it:
335 </p>
336
337 <pre caption="An empty partition table">
338 Disk /dev/hda: 30.0 GB, 30005821440 bytes
339 240 heads, 63 sectors/track, 3876 cylinders
340 Units = cylinders of 15120 * 512 = 7741440 bytes
341
342 Device Boot Start End Blocks Id System
343
344 Command (m for help):
345 </pre>
346
347 <p>
348 Now that the in-memory partition table is empty, we're ready to create the
349 partitions. We will use a default partitioning scheme as discussed previously.
350 Of course, don't follow these instructions to the letter if you don't want the
351 same partitioning scheme!
352 </p>
353
354 </body>
355 </subsection>
356 <subsection>
357 <title>Creating the Boot Partition</title>
358 <body>
359
360 <p>
361 We first create a small boot partition. Type <c>n</c> to create a new partition,
362 then <c>p</c> to select a primary partition, followed by <c>1</c> to select the
363 first primary partition. When prompted for the first cylinder, hit enter. When
364 prompted for the last cylinder, type <c>+32M</c> to create a partition 32 Mbyte
365 in size:
366 </p>
367
368 <pre caption="Creating the boot partition">
369 Command (m for help): <i>n</i>
370 Command action
371 e extended
372 p primary partition (1-4)
373 <i>p</i>
374 Partition number (1-4): <i>1</i>
375 First cylinder (1-3876, default 1): <comment>(Hit Enter)</comment>
376 Using default value 1
377 Last cylinder or +size or +sizeM or +sizeK (1-3876, default 3876): <i>+32M</i>
378 </pre>
379
380 <p>
381 Now, when you type <c>p</c>, you should see the following partition printout:
382 </p>
383
384 <pre caption="Created boot partition">
385 Command (m for help): <i>p</i>
386
387 Disk /dev/hda: 30.0 GB, 30005821440 bytes
388 240 heads, 63 sectors/track, 3876 cylinders
389 Units = cylinders of 15120 * 512 = 7741440 bytes
390
391 Device Boot Start End Blocks Id System
392 /dev/hda1 1 14 105808+ 83 Linux
393 </pre>
394
395 <p>
396 We need to make this partition bootable. Type <c>a</c> to toggle the bootable
397 flag on a partition and select <c>1</c>. If you press <c>p</c> again, you will
398 notice that an <path>*</path> is placed in the "Boot" column.
399 </p>
400
401 </body>
402 </subsection>
403 <subsection>
404 <title>Creating the Swap Partition</title>
405 <body>
406
407 <p>
408 Let's now create the swap partition. To do this, type <c>n</c> to create a new
409 partition, then <c>p</c> to tell fdisk that you want a primary partition. Then
410 type <c>2</c> to create the second primary partition, <path>/dev/hda2</path> in
411 our case. When prompted for the first cylinder, hit enter. When prompted for
412 the last cylinder, type <c>+512M</c> to create a partition 512MB in size. After
413 you've done this, type <c>t</c> to set the partition type, <c>2</c> to select
414 the partition you just created and then type in <c>82</c> to set the partition
415 type to "Linux Swap". After completing these steps, typing <c>p</c> should
416 display a partition table that looks similar to this:
417 </p>
418
419 <pre caption="Partition listing after creating a swap partition">
420 Command (m for help): <i>p</i>
421
422 Disk /dev/hda: 30.0 GB, 30005821440 bytes
423 240 heads, 63 sectors/track, 3876 cylinders
424 Units = cylinders of 15120 * 512 = 7741440 bytes
425
426 Device Boot Start End Blocks Id System
427 /dev/hda1 * 1 14 105808+ 83 Linux
428 /dev/hda2 15 81 506520 82 Linux swap
429 </pre>
430
431 </body>
432 </subsection>
433 <subsection>
434 <title>Creating the Root Partition</title>
435 <body>
436
437 <p>
438 Finally, let's create the root partition. To do this, type <c>n</c> to create a
439 new partition, then <c>p</c> to tell fdisk that you want a primary partition.
440 Then type <c>3</c> to create the third primary partition, <path>/dev/hda3</path>
441 in our case. When prompted for the first cylinder, hit enter. When prompted for
442 the last cylinder, hit enter to create a partition that takes up the rest of the
443 remaining space on your disk. After completing these steps, typing <c>p</c>
444 should display a partition table that looks similar to this:
445 </p>
446
447 <pre caption="Partition listing after creating the root partition">
448 Command (m for help): <i>p</i>
449
450 Disk /dev/hda: 30.0 GB, 30005821440 bytes
451 240 heads, 63 sectors/track, 3876 cylinders
452 Units = cylinders of 15120 * 512 = 7741440 bytes
453
454 Device Boot Start End Blocks Id System
455 /dev/hda1 * 1 14 105808+ 83 Linux
456 /dev/hda2 15 81 506520 82 Linux swap
457 /dev/hda3 82 3876 28690200 83 Linux
458 </pre>
459
460 </body>
461 </subsection>
462 <subsection>
463 <title>Saving the Partition Layout</title>
464 <body>
465
466 <p>
467 To save the partition layout and exit <c>fdisk</c>, type <c>w</c>.
468 </p>
469
470 <pre caption="Save and exit fdisk">
471 Command (m for help): <i>w</i>
472 </pre>
473
474 <p>
475 Now that your partitions are created, you can now continue with <uri
476 link="#filesystems">Creating Filesystems</uri>.
477 </p>
478
479 </body>
480 </subsection>
481 </section>
482 <section id="filesystems">
483 <title>Creating Filesystems</title>
484 <subsection>
485 <title>Introduction</title>
486 <body>
487
488 <p>
489 Now that your partitions are created, it is time to place a filesystem on them.
490 If you don't care about what filesystem to choose and are happy with what we use
491 as default in this handbook, continue with <uri
492 link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
493 Otherwise read on to learn about the available filesystems...
494 </p>
495
496 </body>
497 </subsection>
498 <subsection>
499 <title>Filesystems?</title>
500 <body>
501
502 <p>
503 Several filesystems are available. Some of them are found stable on the amd64
504 architecture, others aren't. The following filesystems are found to be stable:
505 ext2 and ext3. jfs and reiserfs may work but need more testing. If you're
506 really adventurous you can try the unsupported filesystems.
507 </p>
508
509 <p>
510 <b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata
511 journaling, which means that routine ext2 filesystem checks at startup time can
512 be quite time-consuming. There is now quite a selection of newer-generation
513 journaled filesystems that can be checked for consistency very quickly and are
514 thus generally preferred over their non-journaled counterparts. Journaled
515 filesystems prevent long delays when you boot your system and your filesystem
516 happens to be in an inconsistent state.
517 </p>
518
519 <p>
520 <b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata
521 journaling for fast recovery in addition to other enhanced journaling modes
522 like full data and ordered data journaling. It uses a hashed B*-tree index that
523 enables high performance in almost all situations. In short, ext3 is a very
524 good and reliable filesystem.
525 </p>
526
527 <p>
528 <b>ReiserFS</b> is a B*-tree based filesystem that has very good overall
529 performance and greatly outperforms both ext2 and ext3 when dealing with small
530 files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales
531 extremely well and has metadata journaling. ReiserFS is solid and usable as
532 both general-purpose filesystem and for extreme cases such as the creation of
533 large filesystems, very large files and directories containing tens of
534 thousands of small files.
535 </p>
536
537 <p>
538 <b>XFS</b> is a filesystem with metadata journaling which comes with a robust
539 feature-set and is optimized for scalability. We only recommend using this
540 filesystem on Linux systems with high-end SCSI and/or fibre channel storage and
541 an uninterruptible power supply. Because XFS aggressively caches in-transit data
542 in RAM, improperly designed programs (those that don't take proper precautions
543 when writing files to disk and there are quite a few of them) can lose a good
544 deal of data if the system goes down unexpectedly.
545 </p>
546
547 <p>
548 <b>JFS</b> is IBM's high-performance journaling filesystem. It has recently
549 become production-ready and there hasn't been a sufficient track record to
550 comment positively nor negatively on its general stability at this point.
551 </p>
552
553 </body>
554 </subsection>
555 <subsection id="filesystems-apply">
556 <title>Applying a Filesystem to a Partition</title>
557 <body>
558
559 <p>
560 To create a filesystem on a partition or volume, there are tools available for
561 each possible filesystem:
562 </p>
563
564 <table>
565 <tr>
566 <th>Filesystem</th>
567 <th>Creation Command</th>
568 </tr>
569 <tr>
570 <ti>ext2</ti>
571 <ti><c>mke2fs</c></ti>
572 </tr>
573 <tr>
574 <ti>ext3</ti>
575 <ti><c>mke2fs -j</c></ti>
576 </tr>
577 <tr>
578 <ti>reiserfs</ti>
579 <ti><c>mkreiserfs</c></ti>
580 </tr>
581 <tr>
582 <ti>xfs</ti>
583 <ti><c>mkfs.xfs</c></ti>
584 </tr>
585 <tr>
586 <ti>jfs</ti>
587 <ti><c>mkfs.jfs</c></ti>
588 </tr>
589 </table>
590
591 <p>
592 For instance, to have the boot partition (<path>/dev/hda1</path> in our
593 example) in ext2 and the root partition (<path>/dev/hda3</path> in our example)
594 in ext3 (as in our example), you would use:
595 </p>
596
597 <pre caption="Applying a filesystem on a partition">
598 # <i>mke2fs /dev/hda1</i>
599 # <i>mke2fs -j -O dir_index /dev/hda3</i>
600 </pre>
601
602 <p>
603 Now create the filesystems on your newly created partitions (or logical
604 volumes).
605 </p>
606
607 </body>
608 </subsection>
609 <subsection>
610 <title>Activating the Swap Partition</title>
611 <body>
612
613 <p>
614 <c>mkswap</c> is the command that is used to initialize swap partitions:
615 </p>
616
617 <pre caption="Creating a Swap signature">
618 # <i>mkswap /dev/hda2</i>
619 </pre>
620
621 <p>
622 To activate the swap partition, use <c>swapon</c>:
623 </p>
624
625 <pre caption="Activating the swap partition">
626 # <i>swapon /dev/hda2</i>
627 </pre>
628
629 <p>
630 Create and activate the swap with the commands mentioned above.
631 </p>
632
633 </body>
634 </subsection>
635 </section>
636 <section>
637 <title>Mounting</title>
638 <body>
639
640 <p>
641 Now that your partitions are initialized and are housing a filesystem, it is
642 time to mount those partitions. Use the <c>mount</c> command. Don't forget to
643 create the necessary mount directories for every partition you created. As an
644 example we mount the root and boot partition:
645 </p>
646
647 <pre caption="Mounting partitions">
648 # <i>mount /dev/hda3 /mnt/gentoo</i>
649 # <i>mkdir /mnt/gentoo/boot</i>
650 # <i>mount /dev/hda1 /mnt/gentoo/boot</i>
651 </pre>
652
653 <note>
654 If you want your <path>/tmp</path> to reside on a separate partition, be sure to
655 change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
656 also holds for <path>/var/tmp</path>.
657 </note>
658
659 <p>
660 We will also have to mount the proc filesystem (a virtual interface with the
661 kernel) on <path>/proc</path>. But first we will need to place our files on the partitions.
662 </p>
663
664 <p>
665 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
666 Installation Files</uri>.
667 </p>
668
669 </body>
670 </section>
671 </sections>

  ViewVC Help
Powered by ViewVC 1.1.20