USB flash installation media

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Revision as of 07:57, 17 August 2012 by DSpider (talk | contribs) (Without overwriting the USB drive: minor edit)
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zh-CN:USB Installation Media This page discusses how to put Arch installation media onto a USB key (or "flash drive"). The result will be a LiveCD-like system that will discard all changes when it is shut down. If you would like to install and run Arch Linux on a USB key (i.e. with persistent settings), see Installing Arch Linux on a USB key.

On GNU/Linux

Overwrite the USB drive

First, make sure that the USB device is unmounted and then issue the following command:

Warning: This will irrevocably destroy all data on /dev/sdx.
Warning: Make sure to use /dev/sdx and NOT /dev/sdx1. This is a very common error!
# dd if=archlinux.iso of=/dev/sdx 
Tip: You can also add bs=4M to speed up the process. (*)

How to restore the USB drive

Because the ISO image is a hybrid which can either be burned to a disc or directly written to a USB drive, it doesn't include a standard partition table.

After you install Arch Linux and you're done with the USB drive, you should zero out its first 512 bytes (meaning the boot code from the MBR and the non-standard partition table) if you want to restore it to full capacity:

# dd count=1 bs=512 if=/dev/zero of=/dev/sdx

Then create a new partition table (e.g. "msdos") and filesystem (e.g. EXT4, FAT32) using tools such as GParted, cfdisk, etc.

Without overwriting the USB drive

This method is slightly more complicated than writing the image directly with dd, but it does keep the drive usable for data storage. Before you begin, make sure that your USB device is formatted as either FAT32, EXT2/3/4 or BTRFS. For interoperability with other operating systems, you probably want to use FAT32. Also, make sure you have the syslinux package (version 4.04 or newer) installed.

1. Copy the "arch" folder from the ISO to the USB drive. For example:

$ sudo su -
# mkdir /mnt/usb
# mount /dev/sdx1 /mnt/usb
# mkdir /mnt/iso
# mount -o loop /media/Storage/Torrents/archlinux-*.iso /mnt/iso
# cp -r /mnt/iso/arch /mnt/usb

2. Install the Syslinux bootloader to the USB drive, along with the boot code installed to the MBR, and make the first partition active:

Warning: Be very careful where you point dd and please use the drive itself in the following commands, not the first partition. This is a very common error.
Note: On some distributions the mbr.bin file may be available as /usr/share/syslinux/mbr.bin.
# extlinux --install /mnt/usb/arch/boot/syslinux
# dd bs=440 conv=notrunc count=1 if=/usr/lib/syslinux/mbr.bin of=/dev/sdx
# parted /dev/sdx toggle 1 boot

3. Adjust the boot configuration files:

Note: While you could label your USB drive "ARCH_201207", perhaps an even better approach is to use the UUID (this way you can re-label it whatever you want later without having to worry about it, or you could just leave it blank). Failing to do either will get you the famous 30 seconds error.

Here's how you can replace the archisolabel=ARCH_201207 part with your equivalent of archisodevice=/dev/disk/by-uuid/47FA-4071 for both config files at the same time, using a single command:

# sed -i "s|label=ARCH_201207|device=/dev/disk/by-uuid/$(blkid -s UUID -o value /dev/sdx1)|" /mnt/usb/arch/boot/syslinux/archiso_sys{32,64}.cfg

Obviously substitute /dev/sdx1. And in case you skipped sudo su - from the first step, run it with root privileges so that blkid can return the value.

4. As a workaround for FAT32 filesystems (unnecessary for EXT4), until Syslinux 4.06(*) is released, the APPEND line from syslinux.cfg should also be replaced:

# sed -i "s|../../|/arch|" /mnt/usb/arch/boot/syslinux/syslinux.cfg

On Mac OS X

To be able to use dd on your usb device on a Mac you have to do some special maneuvers. First of all insert your usb device, OS X will automount it, and run

 diskutil list

in Figure out what your usb device is called - mine was called /dev/disk1. (Just use the `mount` command or `sudo dmesg | tail`.) Now you run

 diskutil unmountDisk /dev/disk1

to unmount the partitions on the device (i.e., /dev/disk1s1) while keeping the device proper (i.e., /dev/disk1). Now we can continue in accordance with the Linux instructions above (but use bs=8192 if you are using the OS X dd, the number comes from 1024*8).

 dd if=image.iso of=/dev/disk1 bs=8192
 20480+0 records in
 20480+0 records out
 167772160 bytes transferred in 220.016918 secs (762542 bytes/sec)

it is probably a good idea to eject your drive before physical removal at this point.

 diskutil eject /dev/disk1

On Windows

Image Writer for Windows

Download win32 disk imager from Run the program. Select the arch image-file and usb stick. The Win32 Disk Imager's file browser assumes image files end with .img, so if the image-file you have selected ends with .iso, you will have to type its name in manually; this difference in suffixes is simply cosmetic however, the image will be written fine regardless. Click on the write button. Now you should be able to boot from the usb stick and install Arch Linux from it.

Linux Live USB Creator

Linux Live USB Creator can be used to create a bootable USB key for Arch either using a manually downloaded iso or automatically downloading the iso itself. It also supports automatic installation of VirtualBox on the USB key which can be used to boot Arch inside Windows. Visit home page for more info.

The Universal USB Installer

Universal USB Installer is a Live Linux USB Creator that allows you to choose from a selection of Linux Distributions to put on your USB Flash Drive.

The Flashnul Way

flashnul is an utility to verify the functionality and maintenance of Flash-Memory (USB-Flash, IDE-Flash, SecureDigital, MMC, MemoryStick, SmartMedia, XD, CompactFlash etc).

From a command prompt, invoke flashnul with -p, and determine which device index is your USB drive. For example, my output looks like this:

C:\>flashnul -p

Avaible physical drives:
Avaible logical disks:

In my case, it is drive E:

When you have determined which device is the correct one, you can write the image to your drive, by invoking flashnul with the device index, -L, and the path to your image. In my case, it would be

C:\>flashnul E: -L path\to\arch.iso

As long as you are really sure you want to write the data, type yes, then wait a bit for it to write. If you get an access denied error, close any Explorer windows you have open.

If under Vista or Win7, you should open the console as administrator, or else flashnul will fail to open the stick as a block device and will only be able to write via the drive handle windows provides

Note: Confirmed that you need to use drive letter as opposed to number. flashnul 1rc1, Windows 7 x64. -bgalakazam

The Cygwin Way

Make sure your Cygwin installation contains the dd package. Or if you do not want to install Cygwin, you can simply download dd for windows from

Place your image file in your home directory, in my case it is:


Run cygwin as administrator (required for cygwin to access hardware). To write to your USB drive use the following command:

dd if=image.iso of=\\.\[x]:

where image.iso is the path to the iso-image file within the cygwin directory and \\.\[x]: is your USB device where x is the windows designated letter, in my case "\\.\d:".

On cygwin 6.0 find out the correct partition with

cat /proc/partitions

and write the ISO image with the information from the output. Example:

Warning: This will irrevocably delete all files on your USB stick, so make sure you do not have any important files on the stick before doing this.
dd if=image.iso of=/dev/sdb

dd for Windows

A GPL licensed dd version for Windows is available at The advantage of this over Cygwin is smaller download. Use it as shown in instructions for Cygwin above.

Boot the entire ISO from RAM

This method uses Syslinux and MEMDISK to load the entire ISO image in RAM, so make sure you have enough RAM to hold it. Once it's done loading and you see the graphical menu you can simply remove the USB stick and maybe even use it on a different machine to start the process all over again. It also allows booting and installing Arch from (and to) the same USB stick.

1. Format the USB stick as FAT32 and create the following folders:


2. Copy the ISO you'd like to boot to the "ISOs" folder (e.g. archlinux-2012.07.15-netinstall-dual.iso), and from the latest release (e.g., copy:

./win32/syslinux.exe to the desktop, or wherever you want.
./memdisk/memdisk to the Settings folder. And while you're in this folder, create a syslinux.cfg file with the following contents:
DEFAULT arch_iso

LABEL arch_iso
        MENU LABEL Arch Setup
        LINUX memdisk
        INITRD /Boot/ISOs/archlinux-2012.07.15-netinstall-dual.iso
        APPEND iso
Tip: If you want to add more distributions (Debian and Parted Magic were tested) you can edit this file. Refer to the Syslinux wiki.

3. Finally, create a *.bat (or *.cmd) file where syslinux.exe is located and run it:

@echo off
syslinux.exe -m -a -d /Boot/Settings X:


Note: If you get the famous 30 seconds error trying to boot the i686 version, press the Template:Keypress key when the menu shows up and add vmalloc=448M at the end, or, add it to the APPEND line from X:\Boot\Settings\syslinux.cfg. This only applies to the MEMDISK method. For reference: If your image is bigger than 128MiB and you have a 32-bit OS, then you have to increase the maximum memory usage of vmalloc. (*)