Difference between revisions of "USB storage devices"
| Line 14: | Line 14: | ||
A lightweight solution to automount harddrives using udev, for systems with only one user, is the following: create a file named {{Ic|/etc/udev/rules.d/automount.rules}} with the following content: | A lightweight solution to automount harddrives using udev, for systems with only one user, is the following: create a file named {{Ic|/etc/udev/rules.d/automount.rules}} with the following content: | ||
| − | {{hc|ACTION=="add", ENV{DEVTYPE}=="partition", RUN+="domount %N"}} | + | {{hc|<nowiki>ACTION=="add", ENV{DEVTYPE}=="partition", RUN+="domount %N"</nowiki>}} |
and a file (executable by root) named {{Ic|/usr/lib/udev/domount}} with: | and a file (executable by root) named {{Ic|/usr/lib/udev/domount}} with: | ||
| − | {{hc|#!/bin/sh | + | {{hc|<nowiki>#!/bin/sh |
export DISPLAY=:0 | export DISPLAY=:0 | ||
| Line 36: | Line 36: | ||
chmod a+x /tmp/script | chmod a+x /tmp/script | ||
su al -c 'lxterminal -e /tmp/script' | su al -c 'lxterminal -e /tmp/script' | ||
| − | sleep 1; rm -f /tmp/script}} | + | sleep 1; rm -f /tmp/script</nowiki>}} |
(replace the 1000 with your UID and GID, lxterminal with your favorite terminal emulator, and zsh with your shell). | (replace the 1000 with your UID and GID, lxterminal with your favorite terminal emulator, and zsh with your shell). | ||
Revision as of 15:05, 6 August 2012
This document describes how to use the popular USB memory sticks with Linux. However, it is also valid for other devices such as digital cameras that act as if they were just a USB storage.
Mounting USB devices
If you have an up-to-date system with the standard Arch kernel and a modern Desktop Environment your device should just show up on your desktop, no need to open a console.
Otherwise see sections below.
Auto-mounting with udev
See Udev:Auto mounting USB devices.
A lightweight solution to automount harddrives using udev, for systems with only one user, is the following: create a file named /etc/udev/rules.d/automount.rules with the following content:
ACTION=="add", ENV{DEVTYPE}=="partition", RUN+="domount %N"
and a file (executable by root) named /usr/lib/udev/domount with:
#!/bin/sh
export DISPLAY=:0
DIR=`cat /etc/fstab|grep $*|awk '{print $2;}'`
if [ "x$DIR" = "x" ]; then
DIR=/run/media/`blkid -o value -s UUID $*`
fi
mkdir -p /run/media
mkdir -p $DIR
mount -o uid=1000,gid=1000,users $* $DIR
cat > /tmp/script << EOF
#!/bin/sh
cd $DIR
zsh
cd
sudo umount $DIR
EOF
chmod a+x /tmp/script
su al -c 'lxterminal -e /tmp/script'
sleep 1; rm -f /tmp/script
(replace the 1000 with your UID and GID, lxterminal with your favorite terminal emulator, and zsh with your shell).
When an harddrive is inserted, it will be mounted, and a Terminal will pop-up. To umount the device, simply press Control+D in the terminal window.
Manual mounting
Getting a kernel that supports usb_storage
If you do not use a custom-made kernel, you are ready to go, for all Arch Linux stock kernels are properly configured. If you do use a custom-made kernel, ensure it is compiled with SCSI-Support, SCSI-Disk-Support and usb_storage. If you use the latest udev, you may just plug your device in and the system will automatically load all necessary kernel modules. Older releases of udev would need hotplug installed too. Otherwise, you can do the same thing manually:
# modprobe usb-storage # modprobe sd_mod (only for non SCSI kernels)
Identifying device
First thing one need to access storage device is it's identifier assigned by kernel.
Using device node names ( /sd* )
This is the simplest way, but assigned name depends on order of insertion. Ways to get node name:
- search in the output of
dmesgfor the kernel device name, you can usegrepto help you find what you are looking for:
$ dmesg | egrep "sd[a-z]"
- running
# fdisk -l
lists all available partition tables.
Using UUID
Every drive creates a UUID (Universally Unique Identifier), these identifiers can be used to track individual drive no matter their device node (ie /dev/sda).
To find the current UUIDs execute:
# blkid -o list -c /dev/null
device fs_type label mount point UUID ------------------------------------------------------------------------------------------ /dev/sda1 ext2 /boot 7f4cef7e-7ee2-489a-b759-d52ba23b692c /dev/sda2 swap (not mounted) a807fff3-e89f-46d0-ab17-9b7ad3efa7b5 /dev/sda3 ext4 / 81917291-fd1a-4ffe-b95f-61c05cfba76f /dev/sda4 ext4 /home c4c23598-19fb-4562-892b-6fb18a09c7d3 /dev/sdb1 ext4 X2 /mnt/X1 4bf265f7-da17-4575-8758-acd40885617b /dev/sdc1 ext4 X1 /mnt/X2 4bf265f7-da17-4575-8758-acd40885617b /dev/sdd1 ext4 Y2 /mnt/Y2 8a976a06-3e56-476f-b73a-ea3cad41d915 /dev/sde1 ext4 Z2 /mnt/Z2 9d35eaae-983f-4eba-abc9-434ecd4da09c /dev/sdf1 ext4 Y1 /mnt/Y1 e2ec37a9-0689-46a8-a07b-0609ce2b7ea2 /dev/sdg1 ext4 Z1 /mnt/Z1 9fa239c1-720f-42e0-8aed-39cf53a743ed /dev/sdj1 ext4 RAPT (not mounted) a9ed7ecb-96ce-40fe-92fa-e07a532ed157 /dev/sdj2 swap <swap> 20826c74-eb6d-46f8-84d8-69b933a4bf3f
At this point you should see a list of your system drives and a long strings of characters. These long strings are the uuids.
- Now connect your USB device and wait for a few seconds . . .
- Reexecute
blkid -o list -c /dev/null
Notice a new device and UUID? That is your USB storage
Mounting USB memory
You need to create the directory in which you are going to mount the device:
# mkdir /mnt/usbstick
As root
Mount the device as root with this command (do not forget to replace device_node by the path you found):
# mount device_node /mnt/usbstick
or
# mount -U UUID /mnt/usbstick
If mount does not recognized the format of the device you can try to use the -t argument, see man mount for details.
As normal user with mount
If you want non-root users to be able to write to the USB stick, you can issue the following command:
$ sudo mount -o gid=users,fmask=113,dmask=002 /dev/sda1 /mnt/usbstick
As normal user with fstab
If you want non-root users to be able to mount a USB memory stick via fstab, add the following line to your /etc/fstab file:
/dev/sda1 /mnt/usbstick vfat user,noauto,noatime,flush 0 0
or better:
UUID=E8F1-5438 /mnt/usbstick vfat user,noauto,noatime,flush 0 0
(see description of user and other options in the main article)
Now, any user can mount it with:
$ mount /mnt/usbstick
And unmount it with:
$ umount /mnt/usbstick
Poor copy performance to USB pendrive
If you experienced slow copy speed to pendrive (mainly in KDE), then merge this three line to the end of your /etc/rc.local:
echo madvise > /sys/kernel/mm/transparent_hugepage/enabled echo madvise > /sys/kernel/mm/transparent_hugepage/defrag echo 0 > /sys/kernel/mm/transparent_hugepage/khugepaged/defrag
And paste these at the end of your /etc/sysctl.conf
kernel.shmmax=134217728 vm.dirty_background_bytes = 4194304 vm.dirty_bytes = 4194304
And reboot. This also reduces the freezes of the KDE's panel.