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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 1.13 2005/07/02 12:12:46 swift Exp $ -->
4
5 <guide link="/doc/en/gentoo-x86-tipsntricks.xml">
6 <title>Gentoo/x86 Installation Tips &amp; Tricks</title>
7 <author title="Author">
8 <mail link="swift@gentoo.org">Sven Vermeulen</mail>
9 </author>
10
11 <abstract>
12 The Gentoo installation allows for very flexible approaches to the various
13 installation methods. As it is almost impossible to insert every single tip or
14 trick in the installation instructions this document tries to deal with all
15 submitted tips and tricks for reference purposes.
16 </abstract>
17
18 <license/>
19
20 <version>1.8</version>
21 <date>2005-07-02</date>
22
23 <chapter>
24 <title>Introduction</title>
25 <section>
26 <title>Preliminary</title>
27 <body>
28
29 <p>
30 This document contains various tips and tricks for the Gentoo/x86 installation.
31 Most of them are discussed in a dense way - they are meant as an addendum to the
32 installation instructions and not as a replacement.
33 </p>
34
35 </body>
36 </section>
37 <section>
38 <title>Contents</title>
39 <body>
40
41 <p>
42 <b>Advanced Installations</b>
43 </p>
44
45 <ul>
46 <li><uri link="#software-raid">Software RAID</uri></li>
47 <li><uri link="#ata-raid-2.4">ATA RAID using 2.4 kernels</uri></li>
48 <li><uri link="#livecd-kernel">Using the LiveCD kernel</uri></li>
49 </ul>
50
51 <p>
52 <b>Simplifying the Installation</b>
53 </p>
54
55 <ul>
56 <li><uri link="#leave_terminal">Leaving the Terminal</uri></li>
57 </ul>
58
59 <p>
60 <b>Fixing Errors/Issues</b>
61 </p>
62
63 <ul>
64 <li><uri link="#checking-disks">Extensive Testing of your Disks</uri></li>
65 <li>
66 <uri link="#recover">Recovering from a malfunctioning installation</uri>
67 </li>
68 </ul>
69
70 </body>
71 </section>
72 </chapter>
73 <chapter>
74 <title>Advanced Installations</title>
75 <section id="software-raid">
76 <title>Software RAID</title>
77 <body>
78
79 <note>
80 If you are not familiar with software raid, please read the <uri
81 link="http://tldp.org/HOWTO/Software-RAID-HOWTO.html">Software-RAID-HOWTO</uri>.
82 </note>
83
84 <p>
85 Once you are booted from the LiveCD, load the appropriate RAID modules. For
86 instance, if you plan on using RAID-1:
87 </p>
88
89 <pre caption="Loading the RAID-1 module">
90 # <i>modprobe raid1</i>
91 </pre>
92
93 <p>
94 When you partition your disks, make sure that your partitions use <c>fd</c>
95 (Linux raid autodetect) as Partition Type instead of <c>83</c> (Linux native).
96 You can alter the partition type using the <c>t</c> command in <c>fdisk</c>.
97 </p>
98
99 <p>
100 Now before we start creating the RAID arrays, we need to create the metadevice
101 nodes:
102 </p>
103
104 <pre caption="Creating metadevice nodes">
105 # <i>mknod /dev/md0 b 9 0</i>
106 # <i>mknod /dev/md1 b 9 1</i>
107 # <i>mknod /dev/md2 b 9 2</i>
108 </pre>
109
110 <p>
111 After partitioning, create the <path>/etc/mdadm.conf</path> file (yes, indeed,
112 on the LiveCD environment) using <c>mdadm</c>, an advanced tool for <uri
113 link="http://www.linuxdevcenter.com/pub/a/linux/2002/12/05/RAID.html">RAID
114 management</uri>. For instance, to have your boot, swap and root partition
115 mirrored (RAID-1) covering <path>/dev/sda</path> and <path>/dev/sdb</path>,
116 you can use:
117 </p>
118
119 <pre caption="mdadm command example">
120 # <i>mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1</i>
121 # <i>mdadm --create --verbose /dev/md1 --level=1 --raid-devices=2 /dev/sda2 /dev/sdb2</i>
122 # <i>mdadm --create --verbose /dev/md2 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3</i>
123 <comment>(Save information about the created devices in mdadm.conf)</comment>
124 # <i>mdadm --detail --scan > /etc/mdadm.conf</i>
125 </pre>
126
127 <p>
128 The Linux Software RAID driver will start creating the metadevices. You can see
129 its progress in <path>/proc/mdstat</path>. Wait until the metadevices are
130 completely finished before proceeding.
131 </p>
132
133 <p>
134 From now onwards, use <path>/dev/md0</path> for the boot partition,
135 <path>/dev/md1</path> for the swap partition and <path>/dev/md2</path> for the
136 root partition.
137 </p>
138
139 <p>
140 After mounting <path>/dev/md2</path> on <path>/mnt/gentoo</path>, don't forget
141 to copy over <path>/etc/mdadm.conf</path> to <path>/mnt/gentoo/etc</path>. You
142 should also bind-mount <path>/dev</path> to <path>/mnt/gentoo/dev</path> or
143 create the device nodes in the chrooted environment as well:
144 </p>
145
146 <pre caption="Bind-mounting /dev to /mnt/gentoo/dev">
147 # <i>mount -o bind /dev /mnt/gentoo/dev</i>
148 </pre>
149
150 <p>
151 When you're configuring your kernel, make sure you have the appropriate RAID
152 support <e>in</e> your kernel and not as module.
153 </p>
154
155 <p>
156 When installing extra tools, emerge <c>mdadm</c> as well. Note that this
157 isn't available on all LiveCDs so you might not be able to install Gentoo on a
158 Software RAID when using a networkless installation!
159 </p>
160
161 <p>
162 When configuring your bootloader, make sure it gets installed in the MBR of
163 <e>both</e> disks if you use mirroring.
164 </p>
165
166 </body>
167 </section>
168 <section id="ata-raid-2.4">
169 <title>ATA RAID using 2.4 kernels</title>
170 <body>
171
172 <p>
173 Make sure you boot your LiveCD using the <c>doataraid</c> option. Once booted,
174 check the contents of <path>/dev/ataraid</path>. It should contain various
175 <path>disc*</path> directories for each harddisk available in the ATA RAID. An
176 entire disk is displayed as <path>disc</path> while partitions are
177 <path>part*</path>.
178 </p>
179
180 <p>
181 Write down the various <path>/dev/ataraid/disc*/*</path> device files that you
182 use to install Gentoo on. You will need to substitute the <path>/dev/hda</path>
183 examples in the installation with this path.
184 </p>
185
186 <p>
187 Before chrooting, bind-mount the <path>/dev</path> structure in the new
188 environment:
189 </p>
190
191 <pre caption="Bind-mounting /dev">
192 # <i>mount -o bind /dev /mnt/gentoo/dev</i>
193 </pre>
194
195 <p>
196 When configuring your kernel, make sure you enable support for your ATA RAID
197 chipset and options. For instance, a popular ATA RAID system is a <e>Promise
198 FastTrack built-in RAID</e> in which case you definitely need <c>Promise
199 FastTrack Options</c> built in into your kernel.
200 </p>
201
202 <p>
203 When configuring GRUB, you first have to create a GRUB bootdisk. This is not as
204 hard as you think. First install GRUB as you would, but when you come to the
205 part where GRUB is getting installed in the MBR, follow the following
206 instructions:
207 </p>
208
209 <pre caption="Creating a GRUB bootdisk">
210 # <i>cd /boot/grub</i>
211 # <i>dd if=stage1 of=/dev/fd0 bs=512 count=1</i>
212 # <i>dd if=stage2 of=/dev/fd0 bs=512 seek=1</i>
213 </pre>
214
215 <p>
216 You still need to write your <path>grub.conf</path> file. This is no different
217 from the installation instructions, just make sure that your <c>root=</c> points
218 to the ATA RAID device.
219 </p>
220
221 <p>
222 After finishing the installation, boot with your GRUB bootdisk. You will be
223 greeted by a GRUB prompt. Now configure GRUB to boot from the ATA RAID device:
224 </p>
225
226 <pre caption="Installing GRUB on the ATA RAID">
227 grub&gt; root (hd0,x)
228 grub&gt; setup (hd0)
229 grub&gt; quit
230 </pre>
231
232 <p>
233 Now reboot (with the GRUB bootfloppy removed).
234 </p>
235
236 <p>
237 LILO users can safely use the instructions mentioned in the installation
238 instructions.
239 </p>
240
241 </body>
242 </section>
243 <section id="livecd-kernel">
244 <title>Using the LiveCD kernel</title>
245 <body>
246
247 <p>
248 If you don't want to compile a kernel yourself you can use the kernel from the
249 LiveCD and copy it to your system. When you come to the point that you're asked
250 to compile a kernel, go to another terminal (press Alt-F2) and log in with the
251 root password you've supplied at the beginning of the installation.
252 </p>
253
254 <p>
255 Copy over the kernel and modules to your Gentoo system:
256 </p>
257
258 <pre caption="Copying over the LiveCD kernel">
259 <comment>(${KN} is the kernel name, usually something like 'gentoo' or 'smp')</comment>
260 cdimage ~# <i>cp /mnt/cdrom/isolinux/${KN} /mnt/cdrom/isolinux/${KN}.gz /mnt/gentoo/boot</i>
261 cdimage ~# <i>mkdir -p /mnt/gentoo/lib/modules</i>
262 cdiamge ~# <i>cp -Rp /lib/modules/`uname -r` /mnt/gentoo/lib/modules</i>
263 </pre>
264
265 <p>
266 Make sure you <c>emerge hotplug</c> and have it added to the boot runlevel. To
267 have all modules that are currently running (from the LiveCD) loaded during
268 bootup of your Gentoo system, run the following command from within the chrooted
269 environment:
270 </p>
271
272 <pre caption="Adding all running modules to the modules.conf file">
273 # <i>cat /proc/modules | cut -d ' ' -f 1 &gt;&gt; \</i>
274 <i>/etc/modules.autoload.d/kernel-`uname -r | cut -d . -f -2`</i>
275 # <i>modules-update</i>
276 </pre>
277
278 </body>
279 </section>
280 </chapter>
281
282 <chapter>
283 <title>Simplifying the Installation</title>
284 <section id="leave_terminal">
285 <title>Leaving your Terminal</title>
286 <body>
287
288 <p>
289 Many people want to leave their system when it's compiling. In certain cases
290 this is rather difficult as the installation is done in a public environment
291 where you cannot trust everyone. If this is the case, you want to be able to
292 perform the compilation in the background and log out from all terminals.
293 </p>
294
295 <p>
296 There are several possible solutions for this. The first one is to use
297 <c>screen</c>. After booting the LiveCD, set your root password and start a
298 screen session:
299 </p>
300
301 <note>
302 Not all LiveCDs provide screen. If this is the case, you will have to use one of
303 the other methods described in this section.
304 </note>
305
306 <pre caption="Starting a screen session">
307 # <i>screen -S gentoo</i>
308 </pre>
309
310 <p>
311 Once inside the screen session you can perform the entire installation. When you
312 want to leave your terminal, press <c>Ctrl-a, d</c> (that is, control and a at
313 the same time, then followed by a d) to <e>detach</e> your screen session. You
314 can now safely log out of your system.
315 </p>
316
317 <p>
318 To regain access to your terminal, log in as root again and <e>attach</e> to
319 the running screen session:
320 </p>
321
322 <pre caption="Attaching to a screen session">
323 # <i>screen -x gentoo</i>
324 </pre>
325
326 <p>
327 If you can't use screen, there is still a way to leave your terminal. Follow the
328 installation instructions, but when you come to the point where a long-term
329 compilation would be started (for instance the <c>./scripts/bootstrap.sh</c>
330 step), use <c>nohup</c> which allows for a process to continue even when you log
331 out. Don't forget the trailing "&amp;", otherwise the process won't be placed in
332 the background! Remember where you are (the <c>pwd</c> command will show you
333 that) as you will need to know this later on.
334 </p>
335
336 <pre caption="Using nohup">
337 # <i>pwd</i>
338 /usr/portage
339 # <i>nohup ./scripts/bootstrap.sh &amp;</i>
340 </pre>
341
342 <p>
343 Now exit the chrooted environment (<c>exit</c>) and the LiveCD session. Your
344 compilation will continue in the background.
345 </p>
346
347 <p>
348 When you want to check the compilation, log in as root (on the LiveCD) and
349 chroot back into your environment and go to the directory where you left off:
350 </p>
351
352 <pre caption="Chrooting back">
353 # <i>chroot /mnt/gentoo /bin/bash</i>
354 # <i>env-update &amp;&amp; source /etc/profile</i>
355 # <i>cd /usr/portage</i>
356 </pre>
357
358 <p>
359 Now use the <c>less</c> command on the <path>nohup.out</path> file that is
360 situated inside that directory. The compilation will append its output to that
361 file, so if you want to follow the compilation progress, run <c>less
362 nohup.out</c> and press <c>F</c> to follow the changes. When the compilation is
363 finished, you can continue with the next step of the installation instructions.
364 </p>
365
366 <p>
367 If you ever get tired of following the changes, press <c>Ctrl-C</c> followed by
368 a <c>q</c>. This won't stop the compilation process, only the <c>less</c>
369 process.
370 </p>
371
372 </body>
373 </section>
374 </chapter>
375
376 <chapter>
377 <title>Fixing Errors/Issues</title>
378 <section id="checking-disks">
379 <title>Extensive Testing of your Disks</title>
380 <body>
381
382 <p>
383 If you think your disk needs to be thoroughly checked for consistency (bad
384 sectors and such), you can use the <c>-c</c> option while placing the ext2 or
385 ext3 filesystem on it (using <c>mke2fs</c>). This will perform a read-test and
386 will mark all bad blocks as such. If you are really paranoid, use <c>-c -c</c>
387 to perform an extensive read/write test.
388 </p>
389
390 <pre caption="Checking for disk consistency">
391 # <i>mke2fs -j -c /dev/hda3</i>
392 </pre>
393
394 </body>
395 </section>
396 <section id="recover">
397 <title>Recovering from a malfunctioning installation</title>
398 <body>
399
400 <p>
401 If for some reason your Gentoo installation fails, you don't have to redo the
402 installation all over again. Instead, you can safely "go" to the point where you
403 think you made a mistake (or where you think the instructions are flawed) and
404 try a different approach.
405 </p>
406
407 <p>
408 First of all you need to chroot back into your Gentoo Linux environment. Follow
409 the instructions again, but ignore the partitioning steps as your partitions are
410 already created and even populated. You can therefore immediately mount those
411 partitions at <path>/mnt/gentoo</path>. You should also ignore the steps about
412 stage extraction and modifying <path>make.conf</path> - you don't want to
413 overwrite your files do you?
414 </p>
415
416 <p>
417 Once chrooted inside your Gentoo Linux environment, immediately go to the step
418 where you think you should try a different approach. Don't redo all the steps
419 like bootstrapping and such unless that is the place where you think things
420 went wrong.
421 </p>
422
423 <p>
424 For instance, if you believe that you have a wrongly configured
425 <path>grub.conf</path>, you can immediately fire up your editor to update
426 <path>/boot/grub/grub.conf</path>.
427 </p>
428
429 <p>
430 Once you have tried a different approach for your situation, you should consider
431 how much of the subsequent steps you need to perform again. If the subsequent
432 steps are depending on your change, you will need to redo those.
433 </p>
434
435 <p>
436 For instance,
437 </p>
438
439 <ul>
440 <li>
441 if you have changed a variable inside <path>make.conf</path> you will need
442 to do all subsequent compiling since those depend on the settings inside
443 <path>make.conf</path>
444 </li>
445 <li>
446 if you have altered <path>/boot/grub/grub.conf</path> you can immediately
447 exit the chrooted environment and reboot as no subsequent steps are
448 depending on <path>grub.conf</path>
449 </li>
450 <li>
451 if you have recompiled your kernel you only need to make sure that your
452 bootloader configuration points to the correct kernel image (double-check
453 that you mounted your <path>/boot</path>!), then you can exit the chrooted
454 environment and reboot
455 </li>
456 <li>
457 if you have altered <path>/etc/fstab</path> you can exit the chrooted
458 environment and reboot
459 </li>
460 </ul>
461
462 <p>
463 As you can see, for most recovery operations you can immediately reboot. Only in
464 certain cases will you need to redo the subsequent installation steps.
465 </p>
466
467 </body>
468 </section>
469
470 </chapter>
471
472 </guide>

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