Gentoo installation tips and tricks
The Gentoo installation allows for very flexible approaches to the various installation methods. As it is almost impossible to insert every single tip or trick in the installation instructions this document tries to deal with all submitted tips and tricks for reference purposes.
Introduction
Preliminary
This document contains various tips and tricks for the Gentoo/x86 installation. Most of them are discussed in a dense way - they are meant as an addendum to the installation instructions and not as a replacement.
Advanced Installations
Software RAID
If you are not familiar with software RAID, please read the Software RAID HOWTO.
Once you are booted from the Installation CD, load the appropriate RAID modules. For instance, if you plan on using RAID-1:
root #modprobe raid1When you partition your disks, make sure that your partitions use fd (Linux RAID autodetect) as Partition Type instead of 83 (Linux native). You can alter the partition type using the t command in fdisk.
Now before we start creating the RAID arrays, we need to create the metadevice nodes:
root #mknod /dev/md1 b 9 1
root #mknod /dev/md2 b 9 2
root #mknod /dev/md3 b 9 3After partitioning, create the /etc/mdadm.conf file (yes, indeed, on the Installation CD environment) using mdadm, an advanced tool for RAID management. For instance, to have your boot, swap and root partition mirrored (RAID-1) covering /dev/sda and /dev/sdb, you can use:
root #mdadm --create --verbose /dev/md1 --level=1 --raid-devices=2 --metadata=0.90 /dev/sda1 /dev/sdb1
root #mdadm --create --verbose /dev/md2 --level=1 --raid-devices=2 --metadata=0.90 /dev/sda2 /dev/sdb2
root #mdadm --create --verbose /dev/md3 --level=1 --raid-devices=2 --metadata=0.90 /dev/sda3 /dev/sdb3You should not use any form of striping such as RAID-0 or RAID-5 on the partition you boot from. Also, the
--metadata=0.90 is only necessary for these critical file systems. Other filesystems can use more recent metadata formats.The Linux Software RAID driver will start creating the metadevices. You can see its progress in /proc/mdstat. Wait until the metadevices are completely finished before proceeding.
root #mdadm --detail --scan > /etc/mdadm.confFrom now onwards, use /dev/md1 for the boot partition, /dev/md2 for the swap partition and /dev/md3 for the root partition.
Right before chrooting, don't forget to copy over /etc/mdadm.conf to /mnt/gentoo/etc.
When you're configuring your kernel, make sure you have the appropriate RAID support in your kernel and not as module.
When installing extra tools, emerge sys-fs/mdadm as well. Note that this isn't available on all Installation CDs so you might not be able to install Gentoo on a Software RAID when using a networkless installation!
When configuring your bootloader, make sure it gets installed in the MBR of both disks if you use mirroring.
ATA RAID using 2.4 kernels
Make sure you boot your Installation CD using the doataraid option. Once booted, check the contents of /dev/ataraid. It should contain various disc* directories for each hard disk available in the ATA RAID. An entire disk is displayed as disc while partitions are part*.
Write down the various /dev/ataraid/disc*/* device files that you use to install Gentoo on. You will need to substitute the /dev/sda examples in the installation with this path.
Before chrooting, bind-mount the /dev structure in the new environment:
root #mount --rbind /dev /mnt/gentoo/devWhen configuring your kernel, make sure you enable support for your ATA RAID chipset and options. For instance, a popular ATA RAID system is a Promise FastTrack built-in RAID in which case you definitely need Promise FastTrack Options built in into your kernel.
When configuring GRUB, you first have to create a GRUB bootdisk. This is not as hard as you think. First install GRUB as you would, but when you come to the part where GRUB is getting installed in the MBR, follow the following instructions:
root #cd /boot/grub
root #dd if=stage1 of=/dev/fd0 bs=512 count=1
root #dd if=stage2 of=/dev/fd0 bs=512 seek=1You still need to write your grub.conf file. This is no different from the installation instructions, just make sure that your root= points to the ATA RAID device.
After finishing the installation, boot with your GRUB bootdisk. You will be greeted by a GRUB prompt. Now configure GRUB to boot from the ATA RAID device:
grub>root (hd0,x)grub>setup (hd0)
grub>quitNow reboot (with the GRUB bootfloppy removed).
LILO users can safely use the instructions mentioned in the installation instructions.
Using the Installation CD kernel
If you don't want to compile a kernel yourself you can use the kernel from the Installation CD and copy it to your system. When you come to the point that you're asked to compile a kernel, go to another terminal (press Alt + F2) and log in with the root password you've supplied at the beginning of the installation.
Copy over the kernel and modules to your Gentoo system:
${KN} is the kernel name, usually something like 'gentoo' or 'smp'.
root #cp /mnt/cdrom/isolinux/${KN} /mnt/cdrom/isolinux/${KN}.igz /mnt/gentoo/boot
root #mkdir -p /mnt/gentoo/lib/modules
root #cp -Rp /lib/modules/`uname -r` /mnt/gentoo/lib/modulesTo have all modules that are currently running (from the Installation CD) loaded during bootup of your Gentoo system, run the following command from within the chrooted environment:
root #mkdir -p /etc/modules-load.d
root #cut -d ' ' -f 1 /proc/modules >> /etc/modules-load.d/local.conf
Verify the /etc/modules-load.d/local.conf content and update appropriately.
Simplifying the installation
Leaving the terminal
Many people want to leave their system when it's compiling. In certain cases this is rather difficult as the installation is done in a public environment where you cannot trust everyone. If this is the case, you want to be able to perform the compilation in the background and log out from all terminals.
There are several possible solutions for this. The first one is to use screen. After booting the Installation CD, set the root password and start a screen session:
Not all Installation CDs provide screen. If this is the case, you will have to use one of the other methods described in this section.
root #screen -S gentooOnce inside the screen session you can perform the entire installation. When leaving a terminal, press Ctrl + a, d (that is, Ctrl and a at the same time, then followed by a d) to detach the screen session. It is now safe log out of the system (without losing work).
To regain access to the terminal, log in as root again and attach to the running screen session:
root #screen -x gentooIf screen is not an option, there is still a way to leave the terminal. Follow the installation instructions, but when a long-term compilation begins (for instance the ./scripts/bootstrap.sh step), use nohup which allows for a process to continue even when the session closed with a log out. Don't forget the trailing "&", otherwise the process will not be placed in the background! Remember where you are (the pwd command will show you that) as you will need to know this later on.
root #pwd/var/db/repos/gentoo
root #nohup ./scripts/bootstrap.sh &Now exit the chrooted environment (exit) and the Installation CD session. The compilation will continue in the background.
To check the compilation, log in as root (on the Installation CD) and chroot back into the environment, then go to the directory where the session was left off:
root #chroot /mnt/gentoo /bin/bash
root #env-update && source /etc/profile
root #cd /var/db/repos/gentooNow use the less command on the nohup.out file that is situated inside that directory. The compilation will append its output to that file, so if you want to follow the compilation progress, run less nohup.out and press F to follow the changes. When the compilation is finished, continue with the next step of the installation instructions.
When finished following the changes, press Ctrl + c followed by a q. This won't stop the compilation process, only the less process.
Fixing errors and issues
Extensive testing of the disks
If you think your disk needs to be thoroughly checked for consistency (bad sectors and such), you can use the -c (that's lowercase c) option while placing the ext2/ext3/ext4 filesystem on it (using mke2fs). This will format, perform a read-test and mark all bad blocks as such. If you are really paranoid, use -c -c to format your disk and perform an extensive read/write test.
root #mke2fs -j -c /dev/sda3Recovering from a malfunctioning installation
If for some reason your Gentoo installation fails, you don't have to redo the installation all over again. Instead, you can safely "go" to the point where you think you made a mistake (or where you think the instructions are flawed) and try a different approach.
First of all you need to chroot back into your Gentoo Linux environment. Follow the instructions again, but ignore the partitioning steps as your partitions are already created and even populated. You can therefore immediately mount those partitions at /mnt/gentoo. You should also ignore the steps about stage extraction and modifying make.conf - you don't want to overwrite your files do you?
Once chrooted inside your Gentoo Linux environment, immediately go to the step where you think you should try a different approach. Don't redo all the steps like bootstrapping and such unless that is the place where you think things went wrong.
For instance, if you believe that you have a wrongly configured grub.conf, you can immediately fire up your editor to update /boot/grub/grub.conf.
Once you have tried a different approach for your situation, you should consider how much of the subsequent steps you need to perform again. If the subsequent steps are depending on your change, you will need to redo those.
For instance,
- if you have changed a variable inside make.conf you will need to do all subsequent compiling since those depend on the settings inside make.conf
- if you have altered /boot/grub/grub.conf you can immediately exit the chrooted environment and reboot as no subsequent steps are depending on grub.conf
- if you have recompiled your kernel you only need to make sure that your bootloader configuration points to the correct kernel image (double-check that you mounted your /boot!), then you can exit the chrooted environment and reboot
- if you have altered /etc/fstab you can exit the chrooted environment and reboot
As you can see, for most recovery operations you can immediately reboot. Only in certain cases will you need to redo the subsequent installation steps.
This page is based on a document formerly found on our main website gentoo.org.
The following people contributed to the original document: Xavier Neys, nightmorph
They are listed here because wiki history does not allow for any external attribution. If you edit the wiki article, please do not add yourself here; your contributions are recorded on each article's associated history page.