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Fix bug #334167 - Mention ext4 in the handbook. Done for alpha, mips, amd64 and x86. Other arches: please verify and comment on the bug. Thanks to Maciej Grela for reporting.

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-x86+amd64-disk.xml,v 1.13 2009/01/26 08:04:26 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>7</version>
17 <date>2011-08-22</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 <keyval id="arch"/>
34 systems, these are called <e>partitions</e>.
35 </p>
36
37 <p>
38 Partitions are divided in three types:
39 <e>primary</e>, <e>extended</e> and <e>logical</e>.
40 </p>
41
42 <p>
43 A <e>primary</e> partition is a partition which has its information stored in
44 the MBR (master boot record). As an MBR is very small (512 bytes) only four
45 primary partitions can be defined (for instance, <path>/dev/sda1</path> to
46 <path>/dev/sda4</path>).
47 </p>
48
49 <p>
50 An <e>extended</e> partition is a special primary partition (meaning the
51 extended partition must be one of the four possible primary partitions) which
52 contains more partitions. Such a partition didn't exist originally, but as
53 four partitions were too few, it was brought to life to extend the formatting
54 scheme without losing backward compatibility.
55 </p>
56
57 <p>
58 A <e>logical</e> partition is a partition inside the extended partition. Their
59 definitions aren't placed inside the MBR, but are declared inside the extended
60 partition.
61 </p>
62
63 </body>
64 </subsection>
65 <subsection>
66 <title>Advanced Storage</title>
67 <body>
68
69 <p>
70 The <keyval id="arch"/> Installation CDs provide support for EVMS and LVM2.
71 EVMS and LVM2 increase the flexibility offered by your partitioning setup.
72 During the installation instructions, we will focus on "regular" partitions,
73 but it is still good to know EVMS and LVM2 are supported as well.
74 </p>
75
76 </body>
77 </subsection>
78 </section>
79 <section>
80 <title>Designing a Partitioning Scheme</title>
81 <subsection>
82 <title>Default Partitioning Scheme</title>
83 <body>
84
85 <p>
86 If you are not interested in drawing up a partitioning scheme for your system,
87 you can use the partitioning scheme we use throughout this book:
88 </p>
89
90 <table>
91 <tr>
92 <th>Partition</th>
93 <th>Filesystem</th>
94 <th>Size</th>
95 <th>Description</th>
96 </tr>
97 <tr>
98 <ti><path>/dev/sda1</path></ti>
99 <ti>ext2</ti>
100 <ti>32M</ti>
101 <ti>Boot partition</ti>
102 </tr>
103 <tr>
104 <ti><path>/dev/sda2</path></ti>
105 <ti>(swap)</ti>
106 <ti>512M</ti>
107 <ti>Swap partition</ti>
108 </tr>
109 <tr>
110 <ti><path>/dev/sda3</path></ti>
111 <ti>ext3</ti>
112 <ti>Rest of the disk</ti>
113 <ti>Root partition</ti>
114 </tr>
115 </table>
116
117 <p>
118 If you are interested in knowing how big a partition should be, or even how
119 many partitions you need, read on. Otherwise continue now with partitioning
120 your disk by reading <uri link="#fdisk">Using fdisk to Partition your
121 Disk</uri>.
122 </p>
123
124 </body>
125 </subsection>
126 <subsection>
127 <title>How Many and How Big?</title>
128 <body>
129
130 <p>
131 The number of partitions is highly dependent on your environment. For instance,
132 if you have lots of users, you will most likely want to have your
133 <path>/home</path> separate as it increases security and makes backups easier.
134 If you are installing Gentoo to perform as a mailserver, your
135 <path>/var</path> should be separate as all mails are stored inside
136 <path>/var</path>. A good choice of filesystem will then maximise your
137 performance. Gameservers will have a separate <path>/opt</path> as most gaming
138 servers are installed there. The reason is similar for <path>/home</path>:
139 security and backups. You will definitely want to keep <path>/usr</path> big:
140 not only will it contain the majority of applications, the Portage tree alone
141 takes around 500 Mbyte excluding the various sources that are stored in it.
142 </p>
143
144 <p>
145 As you can see, it very much depends on what you want to achieve. Separate
146 partitions or volumes have the following advantages:
147 </p>
148
149 <ul>
150 <li>
151 You can choose the best performing filesystem for each partition or volume
152 </li>
153 <li>
154 Your entire system cannot run out of free space if one defunct tool is
155 continuously writing files to a partition or volume
156 </li>
157 <li>
158 If necessary, file system checks are reduced in time, as multiple checks can
159 be done in parallel (although this advantage is more with multiple disks than
160 it is with multiple partitions)
161 </li>
162 <li>
163 Security can be enhanced by mounting some partitions or volumes read-only,
164 nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
165 </li>
166 </ul>
167
168 <p>
169 However, multiple partitions have one big disadvantage: if not configured
170 properly, you might result in having a system with lots of free space on one
171 partition and none on another. There is also a 15-partition limit for SCSI and
172 SATA.
173 </p>
174
175 <p>
176 As an example partitioning, we show you one for a 20GB disk, used as a
177 demonstration laptop (containing webserver, mailserver, gnome, ...):
178 </p>
179
180 <pre caption="Filesystem usage example">
181 $ <i>df -h</i>
182 Filesystem Type Size Used Avail Use% Mounted on
183 /dev/sda5 ext3 509M 132M 351M 28% /
184 /dev/sda2 ext3 5.0G 3.0G 1.8G 63% /home
185 /dev/sda7 ext3 7.9G 6.2G 1.3G 83% /usr
186 /dev/sda8 ext3 1011M 483M 477M 51% /opt
187 /dev/sda9 ext3 2.0G 607M 1.3G 32% /var
188 /dev/sda1 ext2 51M 17M 31M 36% /boot
189 /dev/sda6 swap 516M 12M 504M 2% &lt;not mounted&gt;
190 <comment>(Unpartitioned space for future usage: 2 GB)</comment>
191 </pre>
192
193 <p>
194 <path>/usr</path> is rather full (83% used) here, but once
195 all software is installed, <path>/usr</path> doesn't tend to grow that much.
196 Although allocating a few gigabytes of disk space for <path>/var</path> may
197 seem excessive, remember that Portage uses this partition by default for
198 compiling packages. If you want to keep <path>/var</path> at a more reasonable
199 size, such as 1GB, you will need to alter your <c>PORTAGE_TMPDIR</c> variable
200 in <path>/etc/make.conf</path> to point to the partition with enough free space
201 for compiling extremely large packages such as OpenOffice.
202 </p>
203
204 </body>
205 </subsection>
206 </section>
207 <section id="fdisk">
208 <title>Using fdisk to Partition your Disk</title>
209 <subsection>
210 <body>
211
212 <p>
213 The following parts explain how to create the example partition layout
214 described previously, namely:
215 </p>
216
217 <table>
218 <tr>
219 <th>Partition</th>
220 <th>Description</th>
221 </tr>
222 <tr>
223 <ti><path>/dev/sda1</path></ti>
224 <ti>Boot partition</ti>
225 </tr>
226 <tr>
227 <ti><path>/dev/sda2</path></ti>
228 <ti>Swap partition</ti>
229 </tr>
230 <tr>
231 <ti><path>/dev/sda3</path></ti>
232 <ti>Root partition</ti>
233 </tr>
234 </table>
235
236 <p>
237 Change your partition layout according to your own preference.
238 </p>
239
240 </body>
241 </subsection>
242 <subsection>
243 <title>Viewing the Current Partition Layout</title>
244 <body>
245
246 <p>
247 <c>fdisk</c> is a popular and powerful tool to split your disk into partitions.
248 Fire up <c>fdisk</c> on your disk (in our example, we use
249 <path>/dev/sda</path>):
250 </p>
251
252 <pre caption="Starting fdisk">
253 # <i>fdisk /dev/sda</i>
254 </pre>
255
256 <p>
257 Once in <c>fdisk</c>, you'll be greeted with a prompt that looks like this:
258 </p>
259
260 <pre caption="fdisk prompt">
261 Command (m for help):
262 </pre>
263
264 <p>
265 Type <c>p</c> to display your disk's current partition configuration:
266 </p>
267
268 <pre caption="An example partition configuration">
269 Command (m for help): <i>p</i>
270
271 Disk /dev/sda: 240 heads, 63 sectors, 2184 cylinders
272 Units = cylinders of 15120 * 512 bytes
273
274 Device Boot Start End Blocks Id System
275 /dev/sda1 * 1 14 105808+ 83 Linux
276 /dev/sda2 15 49 264600 82 Linux swap
277 /dev/sda3 50 70 158760 83 Linux
278 /dev/sda4 71 2184 15981840 5 Extended
279 /dev/sda5 71 209 1050808+ 83 Linux
280 /dev/sda6 210 348 1050808+ 83 Linux
281 /dev/sda7 349 626 2101648+ 83 Linux
282 /dev/sda8 627 904 2101648+ 83 Linux
283 /dev/sda9 905 2184 9676768+ 83 Linux
284
285 Command (m for help):
286 </pre>
287
288 <p>
289 This particular disk is configured to house seven Linux filesystems (each with
290 a corresponding partition listed as "Linux") as well as a swap partition
291 (listed as "Linux swap").
292 </p>
293
294 </body>
295 </subsection>
296 <subsection>
297 <title>Removing all Partitions</title>
298 <body>
299
300 <p>
301 We will first remove all existing partitions from the disk. Type <c>d</c> to
302 delete a partition. For instance, to delete an existing <path>/dev/sda1</path>:
303 </p>
304
305 <pre caption="Deleting a partition">
306 Command (m for help): <i>d</i>
307 Partition number (1-4): <i>1</i>
308 </pre>
309
310 <p>
311 The partition has been scheduled for deletion. It will no longer show up if you
312 type <c>p</c>, but it will not be erased until your changes have been saved. If
313 you made a mistake and want to abort without saving your changes, type <c>q</c>
314 immediately and hit enter and your partition will not be deleted.
315 </p>
316
317 <p>
318 Now, assuming that you do indeed want to wipe out all the partitions on your
319 system, repeatedly type <c>p</c> to print out a partition listing and then type
320 <c>d</c> and the number of the partition to delete it. Eventually, you'll end
321 up with a partition table with nothing in it:
322 </p>
323
324 <pre caption="An empty partition table">
325 Disk /dev/sda: 30.0 GB, 30005821440 bytes
326 240 heads, 63 sectors/track, 3876 cylinders
327 Units = cylinders of 15120 * 512 = 7741440 bytes
328
329 Device Boot Start End Blocks Id System
330
331 Command (m for help):
332 </pre>
333
334 <p>
335 Now that the in-memory partition table is empty, we're ready to create the
336 partitions. We will use a default partitioning scheme as discussed previously.
337 Of course, don't follow these instructions to the letter if you don't want the
338 same partitioning scheme!
339 </p>
340
341 </body>
342 </subsection>
343 <subsection>
344 <title>Creating the Boot Partition</title>
345 <body>
346
347 <p>
348 We first create a small boot partition. Type <c>n</c> to create a new partition,
349 then <c>p</c> to select a primary partition, followed by <c>1</c> to select the
350 first primary partition. When prompted for the first cylinder, hit enter. When
351 prompted for the last cylinder, type <c>+32M</c> to create a partition 32 Mbyte
352 in size and set its bootable flag:
353 </p>
354
355 <pre caption="Creating the boot partition">
356 Command (m for help): <i>n</i>
357 Command action
358 e extended
359 p primary partition (1-4)
360 <i>p</i>
361 Partition number (1-4): <i>1</i>
362 First cylinder (1-3876, default 1): <comment>(Hit Enter)</comment>
363 Using default value 1
364 Last cylinder or +size or +sizeM or +sizeK (1-3876, default 3876): <i>+32M</i>
365 </pre>
366
367 <p>
368 Now, when you type <c>p</c>, you should see the following partition printout:
369 </p>
370
371 <pre caption="Created boot partition">
372 Command (m for help): <i>p</i>
373
374 Disk /dev/sda: 30.0 GB, 30005821440 bytes
375 240 heads, 63 sectors/track, 3876 cylinders
376 Units = cylinders of 15120 * 512 = 7741440 bytes
377
378 Device Boot Start End Blocks Id System
379 /dev/sda1 1 14 105808+ 83 Linux
380 </pre>
381
382 <p>
383 We need to make this partition bootable. Type <c>a</c> to toggle the bootable
384 flag on a partition and select <c>1</c>. If you press <c>p</c> again, you will
385 notice that an <path>*</path> is placed in the "Boot" column.
386 </p>
387
388 </body>
389 </subsection>
390 <subsection>
391 <title>Creating the Swap Partition</title>
392 <body>
393
394 <p>
395 Let's now create the swap partition. To do this, type <c>n</c> to create a new
396 partition, then <c>p</c> to tell fdisk that you want a primary partition. Then
397 type <c>2</c> to create the second primary partition, <path>/dev/sda2</path> in
398 our case. When prompted for the first cylinder, hit enter. When prompted for
399 the last cylinder, type <c>+512M</c> to create a partition 512MB in size. After
400 you've done this, type <c>t</c> to set the partition type, <c>2</c> to select
401 the partition you just created and then type in <c>82</c> to set the partition
402 type to "Linux Swap". After completing these steps, typing <c>p</c> should
403 display a partition table that looks similar to this:
404 </p>
405
406 <pre caption="Partition listing after creating a swap partition">
407 Command (m for help): <i>p</i>
408
409 Disk /dev/sda: 30.0 GB, 30005821440 bytes
410 240 heads, 63 sectors/track, 3876 cylinders
411 Units = cylinders of 15120 * 512 = 7741440 bytes
412
413 Device Boot Start End Blocks Id System
414 /dev/sda1 * 1 14 105808+ 83 Linux
415 /dev/sda2 15 81 506520 82 Linux swap
416 </pre>
417
418 </body>
419 </subsection>
420 <subsection>
421 <title>Creating the Root Partition</title>
422 <body>
423
424 <p>
425 Finally, let's create the root partition. To do this, type <c>n</c> to create a
426 new partition, then <c>p</c> to tell fdisk that you want a primary partition.
427 Then type <c>3</c> to create the third primary partition, <path>/dev/sda3</path>
428 in our case. When prompted for the first cylinder, hit enter. When prompted for
429 the last cylinder, hit enter to create a partition that takes up the rest of the
430 remaining space on your disk. After completing these steps, typing <c>p</c>
431 should display a partition table that looks similar to this:
432 </p>
433
434 <pre caption="Partition listing after creating the root partition">
435 Command (m for help): <i>p</i>
436
437 Disk /dev/sda: 30.0 GB, 30005821440 bytes
438 240 heads, 63 sectors/track, 3876 cylinders
439 Units = cylinders of 15120 * 512 = 7741440 bytes
440
441 Device Boot Start End Blocks Id System
442 /dev/sda1 * 1 14 105808+ 83 Linux
443 /dev/sda2 15 81 506520 82 Linux swap
444 /dev/sda3 82 3876 28690200 83 Linux
445 </pre>
446
447 </body>
448 </subsection>
449 <subsection>
450 <title>Saving the Partition Layout</title>
451 <body>
452
453 <p>
454 To save the partition layout and exit <c>fdisk</c>, type <c>w</c>.
455 </p>
456
457 <pre caption="Save and exit fdisk">
458 Command (m for help): <i>w</i>
459 </pre>
460
461 <p>
462 Now that your partitions are created, you can continue with <uri
463 link="#filesystems">Creating Filesystems</uri>.
464 </p>
465
466 </body>
467 </subsection>
468 </section>
469 <section id="filesystems">
470 <title>Creating Filesystems</title>
471 <subsection>
472 <title>Introduction</title>
473 <body>
474
475 <p>
476 Now that your partitions are created, it is time to place a filesystem on them.
477 If you don't care about what filesystem to choose and are happy with what we use
478 as default in this handbook, continue with <uri
479 link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
480 Otherwise read on to learn about the available filesystems...
481 </p>
482
483 </body>
484 </subsection>
485
486 <subsection>
487 <include href="hb-install-filesystems.xml"/>
488 </subsection>
489
490 <subsection id="filesystems-apply">
491 <title>Applying a Filesystem to a Partition</title>
492 <body>
493
494 <p>
495 To create a filesystem on a partition or volume, there are tools available for
496 each possible filesystem:
497 </p>
498
499 <table>
500 <tr>
501 <th>Filesystem</th>
502 <th>Creation Command</th>
503 </tr>
504 <tr>
505 <ti>ext2</ti>
506 <ti><c>mkfs.ext2</c></ti>
507 </tr>
508 <tr>
509 <ti>ext3</ti>
510 <ti><c>mkfs.ext3</c></ti>
511 </tr>
512 <tr>
513 <ti>reiserfs</ti>
514 <ti><c>mkreiserfs</c></ti>
515 </tr>
516 <tr>
517 <ti>xfs</ti>
518 <ti><c>mkfs.xfs</c></ti>
519 </tr>
520 <tr>
521 <ti>jfs</ti>
522 <ti><c>mkfs.jfs</c></ti>
523 </tr>
524 </table>
525
526 <p>
527 For instance, to have the boot partition (<path>/dev/sda1</path> in our
528 example) in ext2 and the root partition (<path>/dev/sda3</path> in our example)
529 in ext3 (as in our example), you would use:
530 </p>
531
532 <pre caption="Applying a filesystem on a partition">
533 # <i>mkfs.ext2 /dev/sda1</i>
534 # <i>mkfs.ext3 /dev/sda3</i>
535 </pre>
536
537 <p>
538 Now create the filesystems on your newly created partitions (or logical
539 volumes).
540 </p>
541
542 </body>
543 </subsection>
544 <subsection>
545 <title>Activating the Swap Partition</title>
546 <body>
547
548 <p>
549 <c>mkswap</c> is the command that is used to initialize swap partitions:
550 </p>
551
552 <pre caption="Creating a Swap signature">
553 # <i>mkswap /dev/sda2</i>
554 </pre>
555
556 <p>
557 To activate the swap partition, use <c>swapon</c>:
558 </p>
559
560 <pre caption="Activating the swap partition">
561 # <i>swapon /dev/sda2</i>
562 </pre>
563
564 <p>
565 Create and activate the swap with the commands mentioned above.
566 </p>
567
568 </body>
569 </subsection>
570 </section>
571 <section>
572 <title>Mounting</title>
573 <body>
574
575 <p>
576 Now that your partitions are initialized and are housing a filesystem, it is
577 time to mount those partitions. Use the <c>mount</c> command. Don't forget to
578 create the necessary mount directories for every partition you created. As an
579 example we mount the root and boot partition:
580 </p>
581
582 <pre caption="Mounting partitions">
583 # <i>mount /dev/sda3 /mnt/gentoo</i>
584 # <i>mkdir /mnt/gentoo/boot</i>
585 # <i>mount /dev/sda1 /mnt/gentoo/boot</i>
586 </pre>
587
588 <note>
589 If you want your <path>/tmp</path> to reside on a separate partition, be sure to
590 change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
591 also holds for <path>/var/tmp</path>.
592 </note>
593
594 <p>
595 We will also have to mount the proc filesystem (a virtual interface with the
596 kernel) on <path>/proc</path>. But first we will need to place our files on the partitions.
597 </p>
598
599 <p>
600 Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
601 Installation Files</uri>.
602 </p>
603
604 </body>
605 </section>
606 </sections>

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