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1 <?xml version='1.0' encoding="UTF-8"?>
2 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gentoo-x86-tipsntricks.xml,v 1.15 2005/10/03 20:53:53 rane Exp $ -->
4
5 <guide link="/doc/en/gentoo-x86-tipsntricks.xml">
6 <title>Gentoo/x86 Installation Tips &amp; Tricks</title>
7
8 <author title="Author">
9 <mail link="swift@gentoo.org">Sven Vermeulen</mail>
10 </author>
11 <author title="Editor">
12 <mail link="neysx@gentoo.org">Xavier Neys</mail>
13 </author>
14
15 <abstract>
16 The Gentoo installation allows for very flexible approaches to the various
17 installation methods. As it is almost impossible to insert every single tip or
18 trick in the installation instructions this document tries to deal with all
19 submitted tips and tricks for reference purposes.
20 </abstract>
21
22 <!-- The content of this document is licensed under the CC-BY-SA license -->
23 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
24 <license/>
25
26 <version>1.10</version>
27 <date>2006-03-14</date>
28
29 <chapter>
30 <title>Introduction</title>
31 <section>
32 <title>Preliminary</title>
33 <body>
34
35 <p>
36 This document contains various tips and tricks for the Gentoo/x86 installation.
37 Most of them are discussed in a dense way - they are meant as an addendum to the
38 installation instructions and not as a replacement.
39 </p>
40
41 </body>
42 </section>
43 <section>
44 <title>Contents</title>
45 <body>
46
47 <p>
48 <b>Advanced Installations</b>
49 </p>
50
51 <ul>
52 <li><uri link="#software-raid">Software RAID</uri></li>
53 <li><uri link="#ata-raid-2.4">ATA RAID using 2.4 kernels</uri></li>
54 <li><uri link="#livecd-kernel">Using the Installation CD kernel</uri></li>
55 </ul>
56
57 <p>
58 <b>Simplifying the Installation</b>
59 </p>
60
61 <ul>
62 <li><uri link="#leave_terminal">Leaving the Terminal</uri></li>
63 </ul>
64
65 <p>
66 <b>Fixing Errors/Issues</b>
67 </p>
68
69 <ul>
70 <li><uri link="#checking-disks">Extensive Testing of your Disks</uri></li>
71 <li>
72 <uri link="#recover">Recovering from a malfunctioning installation</uri>
73 </li>
74 </ul>
75
76 </body>
77 </section>
78 </chapter>
79 <chapter>
80 <title>Advanced Installations</title>
81 <section id="software-raid">
82 <title>Software RAID</title>
83 <body>
84
85 <note>
86 If you are not familiar with software raid, please read the <uri
87 link="http://tldp.org/HOWTO/Software-RAID-HOWTO.html">Software-RAID-HOWTO</uri>.
88 </note>
89
90 <p>
91 Once you are booted from the Installation CD, load the appropriate RAID modules. For
92 instance, if you plan on using RAID-1:
93 </p>
94
95 <pre caption="Loading the RAID-1 module">
96 # <i>modprobe raid1</i>
97 </pre>
98
99 <p>
100 When you partition your disks, make sure that your partitions use <c>fd</c>
101 (Linux raid autodetect) as Partition Type instead of <c>83</c> (Linux native).
102 You can alter the partition type using the <c>t</c> command in <c>fdisk</c>.
103 </p>
104
105 <p>
106 Now before we start creating the RAID arrays, we need to create the metadevice
107 nodes:
108 </p>
109
110 <pre caption="Creating metadevice nodes">
111 # <i>mknod /dev/md0 b 9 1</i>
112 # <i>mknod /dev/md1 b 9 2</i>
113 # <i>mknod /dev/md2 b 9 3</i>
114 </pre>
115
116 <p>
117 After partitioning, create the <path>/etc/mdadm.conf</path> file (yes, indeed,
118 on the Installation CD environment) using <c>mdadm</c>, an advanced tool for <uri
119 link="http://www.linuxdevcenter.com/pub/a/linux/2002/12/05/RAID.html">RAID
120 management</uri>. For instance, to have your boot, swap and root partition
121 mirrored (RAID-1) covering <path>/dev/sda</path> and <path>/dev/sdb</path>,
122 you can use:
123 </p>
124
125 <pre caption="mdadm command example">
126 # <i>mdadm --create --verbose /dev/md1 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1</i>
127 # <i>mdadm --create --verbose /dev/md2 --level=1 --raid-devices=2 /dev/sda2 /dev/sdb2</i>
128 # <i>mdadm --create --verbose /dev/md3 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3</i>
129 <comment>(Save information about the created devices in mdadm.conf)</comment>
130 # <i>mdadm --detail --scan > /etc/mdadm.conf</i>
131 </pre>
132
133 <impo>
134 You should not use any form of striping such as raid-0 or raid-5 on your the
135 partition you boot from.
136 </impo>
137
138 <p>
139 The Linux Software RAID driver will start creating the metadevices. You can see
140 its progress in <path>/proc/mdstat</path>. Wait until the metadevices are
141 completely finished before proceeding.
142 </p>
143
144 <p>
145 From now onwards, use <path>/dev/md1</path> for the boot partition,
146 <path>/dev/md2</path> for the swap partition and <path>/dev/md3</path> for the
147 root partition.
148 </p>
149
150 <p>
151 Right before chrooting, don't forget to copy over <path>/etc/mdadm.conf</path>
152 to <path>/mnt/gentoo/etc</path>.
153 </p>
154
155 <p>
156 When you're configuring your kernel, make sure you have the appropriate RAID
157 support <e>in</e> your kernel and not as module.
158 </p>
159
160 <p>
161 When installing extra tools, emerge <c>mdadm</c> as well. Note that this isn't
162 available on all Installation CDs so you might not be able to install Gentoo on
163 a Software RAID when using a networkless installation!
164 </p>
165
166 <p>
167 When configuring your bootloader, make sure it gets installed in the MBR of
168 <e>both</e> disks if you use mirroring.
169 </p>
170
171 </body>
172 </section>
173 <section id="ata-raid-2.4">
174 <title>ATA RAID using 2.4 kernels</title>
175 <body>
176
177 <p>
178 Make sure you boot your Installation CD using the <c>doataraid</c> option. Once booted,
179 check the contents of <path>/dev/ataraid</path>. It should contain various
180 <path>disc*</path> directories for each harddisk available in the ATA RAID. An
181 entire disk is displayed as <path>disc</path> while partitions are
182 <path>part*</path>.
183 </p>
184
185 <p>
186 Write down the various <path>/dev/ataraid/disc*/*</path> device files that you
187 use to install Gentoo on. You will need to substitute the <path>/dev/hda</path>
188 examples in the installation with this path.
189 </p>
190
191 <p>
192 Before chrooting, bind-mount the <path>/dev</path> structure in the new
193 environment:
194 </p>
195
196 <pre caption="Bind-mounting /dev">
197 # <i>mount -o bind /dev /mnt/gentoo/dev</i>
198 </pre>
199
200 <p>
201 When configuring your kernel, make sure you enable support for your ATA RAID
202 chipset and options. For instance, a popular ATA RAID system is a <e>Promise
203 FastTrack built-in RAID</e> in which case you definitely need <c>Promise
204 FastTrack Options</c> built in into your kernel.
205 </p>
206
207 <p>
208 When configuring GRUB, you first have to create a GRUB bootdisk. This is not as
209 hard as you think. First install GRUB as you would, but when you come to the
210 part where GRUB is getting installed in the MBR, follow the following
211 instructions:
212 </p>
213
214 <pre caption="Creating a GRUB bootdisk">
215 # <i>cd /boot/grub</i>
216 # <i>dd if=stage1 of=/dev/fd0 bs=512 count=1</i>
217 # <i>dd if=stage2 of=/dev/fd0 bs=512 seek=1</i>
218 </pre>
219
220 <p>
221 You still need to write your <path>grub.conf</path> file. This is no different
222 from the installation instructions, just make sure that your <c>root=</c> points
223 to the ATA RAID device.
224 </p>
225
226 <p>
227 After finishing the installation, boot with your GRUB bootdisk. You will be
228 greeted by a GRUB prompt. Now configure GRUB to boot from the ATA RAID device:
229 </p>
230
231 <pre caption="Installing GRUB on the ATA RAID">
232 grub&gt; root (hd0,x)
233 grub&gt; setup (hd0)
234 grub&gt; quit
235 </pre>
236
237 <p>
238 Now reboot (with the GRUB bootfloppy removed).
239 </p>
240
241 <p>
242 LILO users can safely use the instructions mentioned in the installation
243 instructions.
244 </p>
245
246 </body>
247 </section>
248 <section id="livecd-kernel">
249 <title>Using the Installation CD kernel</title>
250 <body>
251
252 <p>
253 If you don't want to compile a kernel yourself you can use the kernel from the
254 Installation CD and copy it to your system. When you come to the point that you're asked
255 to compile a kernel, go to another terminal (press Alt-F2) and log in with the
256 root password you've supplied at the beginning of the installation.
257 </p>
258
259 <p>
260 Copy over the kernel and modules to your Gentoo system:
261 </p>
262
263 <pre caption="Copying over the Installation CD kernel">
264 <comment>(${KN} is the kernel name, usually something like 'gentoo' or 'smp')</comment>
265 cdimage ~# <i>cp /mnt/cdrom/isolinux/${KN} /mnt/cdrom/isolinux/${KN}.gz /mnt/gentoo/boot</i>
266 cdimage ~# <i>mkdir -p /mnt/gentoo/lib/modules</i>
267 cdiamge ~# <i>cp -Rp /lib/modules/`uname -r` /mnt/gentoo/lib/modules</i>
268 </pre>
269
270 <p>
271 Make sure you <c>emerge hotplug</c> and have it added to the boot runlevel. To
272 have all modules that are currently running (from the Installation CD) loaded during
273 bootup of your Gentoo system, run the following command from within the chrooted
274 environment:
275 </p>
276
277 <pre caption="Adding all running modules to the modules.conf file">
278 # <i>cat /proc/modules | cut -d ' ' -f 1 &gt;&gt; \</i>
279 <i>/etc/modules.autoload.d/kernel-`uname -r | cut -d . -f -2`</i>
280 # <i>modules-update</i>
281 </pre>
282
283 </body>
284 </section>
285 </chapter>
286
287 <chapter>
288 <title>Simplifying the Installation</title>
289 <section id="leave_terminal">
290 <title>Leaving your Terminal</title>
291 <body>
292
293 <p>
294 Many people want to leave their system when it's compiling. In certain cases
295 this is rather difficult as the installation is done in a public environment
296 where you cannot trust everyone. If this is the case, you want to be able to
297 perform the compilation in the background and log out from all terminals.
298 </p>
299
300 <p>
301 There are several possible solutions for this. The first one is to use
302 <c>screen</c>. After booting the Installation CD, set your root password and start a
303 screen session:
304 </p>
305
306 <note>
307 Not all Installation CDs provide screen. If this is the case, you will have to use one of
308 the other methods described in this section.
309 </note>
310
311 <pre caption="Starting a screen session">
312 # <i>screen -S gentoo</i>
313 </pre>
314
315 <p>
316 Once inside the screen session you can perform the entire installation. When you
317 want to leave your terminal, press <c>Ctrl-a, d</c> (that is, control and a at
318 the same time, then followed by a d) to <e>detach</e> your screen session. You
319 can now safely log out of your system.
320 </p>
321
322 <p>
323 To regain access to your terminal, log in as root again and <e>attach</e> to
324 the running screen session:
325 </p>
326
327 <pre caption="Attaching to a screen session">
328 # <i>screen -x gentoo</i>
329 </pre>
330
331 <p>
332 If you can't use screen, there is still a way to leave your terminal. Follow the
333 installation instructions, but when you come to the point where a long-term
334 compilation would be started (for instance the <c>./scripts/bootstrap.sh</c>
335 step), use <c>nohup</c> which allows for a process to continue even when you log
336 out. Don't forget the trailing "&amp;", otherwise the process won't be placed in
337 the background! Remember where you are (the <c>pwd</c> command will show you
338 that) as you will need to know this later on.
339 </p>
340
341 <pre caption="Using nohup">
342 # <i>pwd</i>
343 /usr/portage
344 # <i>nohup ./scripts/bootstrap.sh &amp;</i>
345 </pre>
346
347 <p>
348 Now exit the chrooted environment (<c>exit</c>) and the Installation CD session. Your
349 compilation will continue in the background.
350 </p>
351
352 <p>
353 When you want to check the compilation, log in as root (on the Installation CD) and
354 chroot back into your environment and go to the directory where you left off:
355 </p>
356
357 <pre caption="Chrooting back">
358 # <i>chroot /mnt/gentoo /bin/bash</i>
359 # <i>env-update &amp;&amp; source /etc/profile</i>
360 # <i>cd /usr/portage</i>
361 </pre>
362
363 <p>
364 Now use the <c>less</c> command on the <path>nohup.out</path> file that is
365 situated inside that directory. The compilation will append its output to that
366 file, so if you want to follow the compilation progress, run <c>less
367 nohup.out</c> and press <c>F</c> to follow the changes. When the compilation is
368 finished, you can continue with the next step of the installation instructions.
369 </p>
370
371 <p>
372 If you ever get tired of following the changes, press <c>Ctrl-C</c> followed by
373 a <c>q</c>. This won't stop the compilation process, only the <c>less</c>
374 process.
375 </p>
376
377 </body>
378 </section>
379 </chapter>
380
381 <chapter>
382 <title>Fixing Errors/Issues</title>
383 <section id="checking-disks">
384 <title>Extensive Testing of your Disks</title>
385 <body>
386
387 <p>
388 If you think your disk needs to be thoroughly checked for consistency (bad
389 sectors and such), you can use the <c>-c</c> option while placing the ext2 or
390 ext3 filesystem on it (using <c>mke2fs</c>). This will perform a read-test and
391 will mark all bad blocks as such. If you are really paranoid, use <c>-c -c</c>
392 to perform an extensive read/write test.
393 </p>
394
395 <pre caption="Checking for disk consistency">
396 # <i>mke2fs -j -c /dev/hda3</i>
397 </pre>
398
399 </body>
400 </section>
401 <section id="recover">
402 <title>Recovering from a malfunctioning installation</title>
403 <body>
404
405 <p>
406 If for some reason your Gentoo installation fails, you don't have to redo the
407 installation all over again. Instead, you can safely "go" to the point where you
408 think you made a mistake (or where you think the instructions are flawed) and
409 try a different approach.
410 </p>
411
412 <p>
413 First of all you need to chroot back into your Gentoo Linux environment. Follow
414 the instructions again, but ignore the partitioning steps as your partitions are
415 already created and even populated. You can therefore immediately mount those
416 partitions at <path>/mnt/gentoo</path>. You should also ignore the steps about
417 stage extraction and modifying <path>make.conf</path> - you don't want to
418 overwrite your files do you?
419 </p>
420
421 <p>
422 Once chrooted inside your Gentoo Linux environment, immediately go to the step
423 where you think you should try a different approach. Don't redo all the steps
424 like bootstrapping and such unless that is the place where you think things
425 went wrong.
426 </p>
427
428 <p>
429 For instance, if you believe that you have a wrongly configured
430 <path>grub.conf</path>, you can immediately fire up your editor to update
431 <path>/boot/grub/grub.conf</path>.
432 </p>
433
434 <p>
435 Once you have tried a different approach for your situation, you should consider
436 how much of the subsequent steps you need to perform again. If the subsequent
437 steps are depending on your change, you will need to redo those.
438 </p>
439
440 <p>
441 For instance,
442 </p>
443
444 <ul>
445 <li>
446 if you have changed a variable inside <path>make.conf</path> you will need
447 to do all subsequent compiling since those depend on the settings inside
448 <path>make.conf</path>
449 </li>
450 <li>
451 if you have altered <path>/boot/grub/grub.conf</path> you can immediately
452 exit the chrooted environment and reboot as no subsequent steps are
453 depending on <path>grub.conf</path>
454 </li>
455 <li>
456 if you have recompiled your kernel you only need to make sure that your
457 bootloader configuration points to the correct kernel image (double-check
458 that you mounted your <path>/boot</path>!), then you can exit the chrooted
459 environment and reboot
460 </li>
461 <li>
462 if you have altered <path>/etc/fstab</path> you can exit the chrooted
463 environment and reboot
464 </li>
465 </ul>
466
467 <p>
468 As you can see, for most recovery operations you can immediately reboot. Only in
469 certain cases will you need to redo the subsequent installation steps.
470 </p>
471
472 </body>
473 </section>
474
475 </chapter>
476
477 </guide>

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