Difference between revisions of "USB storage devices"

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(Auto-mounting with udev: rm section, see Talk:USB Storage Devices#Auto-mounting with udev)
(Maximizing performance: SSD#I.2FO_Scheduler is deprecated)
(4 intermediate revisions by 2 users not shown)
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This is the easiest and most frequently used method. It is used by many [[Desktop environment|desktop environments]], but can be used separately too. See [[Udisks]] for details.
This is the easiest and most frequently used method. It is used by many [[Desktop environment|desktop environments]], but can be used separately too. See [[Udisks]] for details.
== Auto-mounting with udev and systemd ==
{{Deletion|Conflicts with [[Udev#Udisks]] (first sentence). See [[Talk:USB Storage Devices#Auto-mounting with udev]] for details.|Talk:USB Storage Devices#Auto-mounting with udev}}
The above solution does not work, since the RUN directive is for only short processes, and udev enforces this; Scripts will be killed shortly after starting.
Instead, the following solution based on the previous one uses [[systemd]], [[udev]] and [[screen]] to create a more elegant solution.
First, we create a systemd service template ({{ic|/etc/systemd/system/automount@.service}}):
Description=Automount removable storage
ExecStart=/usr/lib/udev/domount %I
We also create a udev rule in {{ic|/etc/udev/rules.d/automount.rules}} very similar to the previous solution.
# ignore sda*
KERNEL!="sd[b-z]*", GOTO="end"
# Also allow SD cards
KERNEL=="mmcblk[0-9]p[0-9]", GOTO="MMC"
# USB: run the script
ACTION=="add", ENV{ID_BUS}=="usb", ENV{DEVTYPE}=="partition", RUN+="/usr/bin/systemctl start automount@%N.service", GOTO="end"
ACTION=="add", ENV{ID_BUS}=="ata", ENV{DEVTYPE}=="partition", RUN+="/usr/bin/systemctl start automount@%N.service", GOTO="end"
ACTION=="add", ENV{DEVTYPE}=="partition", RUN+="/usr/bin/systemctl start automount@%N.service", GOTO="end"
# exit
The juice of the solution is placed in {{ic|/usr/lib/udev/domount}}:
#edit the following variables to suit your needs
MYUID=1000              # your user uid
MYGID=100              # your user gid
MYLOGIN="ME"            # your login
DIR=$(basename $*)
while [ -d "$BASE/$DIR" ]; do
  DIR="$(basename $*).$i"
mkdir -p "$BASE/$DIR" && /bin/mount -o uid=$MYUID,gid=$MYGID "$*" "$BASE/$DIR"
if [ -z "$(su $MYLOGIN -c 'screen -ls | grep AUTOMOUNT')" ]; then
  su $MYLOGIN -c "screen -dm -S AUTOMOUNT -t $DIR $USERSCRIPT $* $BASE $DIR"
su $MYLOGIN -c "screen -S AUTOMOUNT -X screen -t $DIR $USERSCRIPT $* $BASE $DIR"
and in {{ic|/usr/lib/udev/domount_user}}:
echo "$DEV mounted on $BASE/$DIR"
echo "Contents:"
ls --color=auto "$BASE/$DIR"
echo -e "\n------------------------------------\nExit shell to unmount when finished.";
while true; do
  cd $BASE/$DIR
  cd $dir;
  echo "------------------------------------"
  lsof | grep $BASE/$DIR;
  if [ $? -eq 1 ]; then
    echo "------------------------------------";
    echo "The above processes will block the unmount. Please end them.";
sudo /bin/umount "$BASE/$DIR" && sudo rmdir "$BASE/$DIR";
To access the screen session which controls the mounted partitions, simply run
$ screen -d -r AUTOMOUNT
I would suggest putting this in a command key shortcut, for example with [[xbindkeys]] to run in a terminal.
== Manual mounting ==
== Manual mounting ==
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{{Note|This script requires that you have sudo installed and that you have sudo rights.}}
{{Note|This script requires that you have sudo installed and that you have sudo rights.}}
== Troubleshooting ==
=== Poor copy performance to USB pendrive  ===
{{Merge|Maximizing Performance}}
{{Expansion|provide better description, or at least some reference}}
If you experienced slow copy speed to pendrive (mainly in KDE), then append these three lines in a [[systemd]] tmpfile:
w /sys/kernel/mm/transparent_hugepage/enabled - - - - madvise
w /sys/kernel/mm/transparent_hugepage/defrag - - - - madvise
w /sys/kernel/mm/transparent_hugepage/khugepaged/defrag - - - - 0
See also [[Maximizing Performance#Tuning kernel parameters]].

Revision as of 18:53, 5 December 2013

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 device.

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, with no need to open a console.

Auto-mounting with udisks

This is the easiest and most frequently used method. It is used by many desktop environments, but can be used separately too. See Udisks for details.

Manual mounting

Note: Before you decide that Arch Linux does not mount your USB device, be sure to check all available ports. Some ports might not share the same controller, preventing you from mounting the device.

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)
Tip: In case of manually loading modules, you may also need to load the sg module (SCSI generic driver).

Identifying device

First thing one need to access storage device is it's identifier assigned by kernel. See fstab#Identifying filesystems for details.

Tip: To see which device is your USB device, you can compare the output of lsblk -f (explained in the linked article) when the USB device is connected and when it is unconnected.

Mounting USB memory

Merge-arrows-2.pngThis article or section is a candidate for merging with fstab#Writing to FAT32 as Normal User.Merge-arrows-2.png

Notes: This section assumes that the partition on USB storage uses FAT32 or NTFS filesystem, so we have two sections covering the same topic. Either merge everything here or in the linked section. (Discuss in Talk:USB storage devices#)

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


# mount -U UUID /mnt/usbstick

If mount does not recognize the format of the device you can try to use the -t argument, see man mount for details.

Note: If mounting your stick does not work you can try to repartition it, see Format a device.

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:

# 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)

Note: Where /dev/sda1 is replaced with the path to your own usbstick, see Mounting USB memory.

Now, any user can mount it with:

$ mount /mnt/usbstick

And unmount it with:

$ umount /mnt/usbstick

Unmounting devices mounted with udev or systemd/udev

Create an executable file (e.g. /usr/local/bin/unmount.sh):


# Global variables
TITLE="Unmount Utility"

# Populate list of unmountable devices
deviceList=($(findmnt -Do TARGET,SOURCE,FSTYPE | grep -e "sd[b-z]"))
deviceCount=$((${#deviceList[@]} / $COLUMNS))

# Start of program output
echo $TITLE

# Display list of devices that can be unmounted
for ((device=0; device<${#deviceList[@]}; device+=COLUMNS))
  printf "%4s)   %-25s%-13s%-10s\n"\
    "$(($device / $COLUMNS))"\
    "${deviceList[$(($device + 1))]}"\
    "${deviceList[$(($device + 2))]}"

printf "%4s)   Exit\n" "x"

# Get input from user
read -p "Choose a menu option: " input

# Input validation
if [ "$input" = "X" ] || [ "$input" = "x" ]
  echo "Exiting"
  exit 0

if (( $input>=0 )) && (( $input<$deviceCount ))
  echo "Unmounting: ${deviceList[$(($input * $deviceCount))]}"
  sudo umount "${deviceList[$(($input * $deviceCount))]}"
  exit 0
  echo "Invalid menu choice"
  exit 1
Note: This script requires that you have sudo installed and that you have sudo rights.