(Tips & Tricks) Loop device

January 30, 2014

Using the Linux loop device


  1. create a disk for mounting
  2. use loop device for mounting

create a disk for mounting

A 1GB disk:

# dd bs=1024k count=1000 if=/dev/zero of=/storage/disk1 (or faster (no zeros used): truncate -s1000M /storage/disk1)

Partition:

# fdisk /storage/disk1

Result (i.e. with one partition):

Device Boot Start End Blocks Id System /storage/disk1p1 2048 2047999 1022976 83 Linux

use loop device for mounting

Source: http://unix.stackexchange.com/questions/87183/creating-formatted-partition-from-nothing

If on Linux, when loading the loop module, make sure you pass a max_part option to the module so that the loop devices are partitionable.

Check the current value:

cat /sys/module/loop/parameters/max_part

If it’s 0:

modprobe -r loop # unload the module modprobe loop max_part=31

To make this setting persistent, add the following line to /etc/modprobe.conf or to a file in /etc/modprobe.d if that directory exists on your system:

options loop max_part=31

If modprobe -r loop fails because “Module loop is builtin”, you’ll need to add loop.max_part=31 to your kernel command line and reboot. If your bootloader is Grub2, add to it to the value of GRUB_CMDLINE_LINUX in etc/default/grub.

Use losetup to create a loopback device

# losetup /dev/loop0 /storage/disk1 # fdisk -l /dev/loop0 Device Boot Start End Blocks Id System /dev/loop0p1 2048 2047999 1022976 83 Linux

Create filesystem

# mkfs.ext3 -m0 /dev/loop0p1 # mount /dev/loop0p1 /mnt

Check:

# df -h /mnt Filesystem Size Used Avail Use% Mounted on /dev/loop0p1 984M 18M 967M 2% /mnt

Ok!

tags: ,

 
"Toet toet toet, en de groetjes van root"

Powered by Wordpress. Theme by Shlomi Noach, openark.org
© 2017 KwaLinux Trainingen | Algemene voorwaarden | KvK: 10147727 | Disclaimer