Installing Arch Linux on a USB key
zh-CN:Installing Arch Linux on a USB key Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary wiki Template:Article summary wiki Template:Article summary wiki Template:Article summary wiki Template:Article summary end
This page explains how to perform a regular Arch installation onto a USB key (or "flash drive"). In contrast to having a LiveUSB as covered in USB Installation Media, the result will be a persistent installation identical to normal installation to HDD, but on a USB flash drive.
Contents
Preparation
There are various ways of installing Arch on a USB stick, the simplest being from within Arch itself:
- If you are already running Arch, simply install arch-install-scripts and proceed with the Installation Guide just like you would from the iso, but you will not be using /dev/sda. Use
lsblk
to get the /dev/sd* name of your USB key prior to installation.
- An Arch Linux CD/USB can be used to install Arch onto the USB key, via booting the CD/USB and following the Installation Guide. If booting from a Live USB, the installation will have to be made on a different USB stick.
- Or, if you have another linux computer available (it need not be Arch), you can follow the instructions to install from existing linux, and then skip to the configuration section.
Installation
Follow the Installation Guide as you normally would, with these exceptions:
- If cfdisk fails with "Partition ends in the final partial cylinder" fatal error, the only way to proceed is to kill all partitions on the drive. Open another terminal (Template:Keypress), type
fdisk /dev/sdX
(wheresdX
is your usb drive), print partition table (p), check that it's ok, delete it (d) and write changes (w). Now return to cfdisk. - It is highly recommended to review the Tips for Minimizing SSD Read/Writes on the SSD wiki article prior to selecting a filesystem. To sum up, ext4 without a journal should be fine. Recognize that flash has a limited number of writes, and a journaling file system will take some of these as the journal is updated. For this same reason, it is best to forgo a swap partition. Note that this does not affect installing onto a USB hard drive.
- Before creating the initial RAM disk
# mkinitcpio -p linux
, in/etc/mkinitcpio.conf
add theblock
hook to the hooks array right after udev. This is necessary for appropriate module loading in early userspace.
Configuration
- Make sure that
/etc/fstab
includes the correct partition information for/
, and for any other partitions on the USB key. If the usb key is to be booted on several machines, it is quite likely that devices and number of available hard disks vary. So it is advised to use UUID or label:
To get the proper UUIDs for your partitions issue blkid
- menu.lst, the Grub configuration file, should be edited to (loosely) match the following:
With the static /dev/sdaX:
root (hd0,0) kernel /boot/vmlinuz-linux root=/dev/sda1 ro initrd /boot/initramfs-linux.img
When using label your menu.lst should look like this:
root (hd0,0) kernel /boot/vmlinuz-linux root=/dev/disk/by-label/Arch ro initrd /boot/initramfs-linux.img
And for UUID, it should be like this:
root (hd0,0) kernel /boot/vmlinuz-linux root=/dev/disk/by-uuid/3a9f8929-627b-4667-9db4-388c4eaaf9fa ro initrd /boot/initramfs-linux.img
Tips
Painless boot on different machines without using UUID
When using the USB key on various target machines, it is helpful to have multiple entries in GRUB, for machines with different setups. For example, the GRUB configuration could contain:
# (0) Arch Linux title Arch Linux (first drive) root (hd0,0) kernel /boot/vmlinuz-linux root=/dev/sda1 ro initrd /boot/initramfs-linux.img
As well as
# (1) Arch Linux title Arch Linux (second drive) root (hd0,0) kernel /boot/vmlinuz-linux root=/dev/sdb1 ro initrd /boot/initramfs-linux.img
And so forth, giving you the option to select a configuration for a wider variety of machines. However, changing the root=
option in GRUB does not change /etc/fstab
and you must do something (in our example using udev symlink), so the root partition will always be mounted correctly.
- Run
udevinfo -p /sys/block/sdx/ -a
(where sdx is the device name of your usb key) - Find unique information pertaining to your usb key. I chose
SYSFS{model}=="DataTraveler 2.0"
- Make a new file:
/etc/udev/udev.rules/10-my-usb-key.rules
and insert:
KERNEL=="sd**", SYSFS{product}=="DataTraveler 2.0", SYMLINK+="WHATEVERYOUWANTOTCALLIT%n"
- (
KERNEL=="sd**"
is because the kernel - 2.6.16 here - names all usb devices sd as it uses the scsi sub-system and you want to look at every sd device and apply the setting to every partition), withSYSFS{model}==
being the unique identifier collected from udevinfo.
- Run
/etc/start-udev uevents
and make sure the symlinks appears in/dev
. - If so, edit
/etc/fstab
, replacing your old sdx with the new symlinks.
Optimizing for the lifespan of flash memory
- Again, it is highly recommended to review the Tips for Minimizing SSD Read/Writes on the SSD wiki article.