Loop Mounting in Parallel

loop-device

I am doing a project in which I need to mount 100+ loop devices and merge it into AUFS mountpoint
As an observation, for sequentially mounting 90 loop devices, it takes 25 seconds.

I am looking for a solution which will minimize time by mounting loop devices in parallel

Best Answer

I think this is obvious, but

typeset -i M=1
while [ $M -le 102 ]
  do
    mount mysourcedevice$M targetdir$M &
    let M++
done
wait

Should do the job. The wait will wait until all sub-processess are finished, before executing the next command.

Related Solutions

Loop Device – What is a Loop Device When Mounting?

A loop device is a pseudo ("fake") device (actually just a file) that acts as a block-based device. You want to mount a file disk1.iso that will act as an entire filesystem, so you use loop.

The -o is short for --options.

And the last thing, if you want to search for "-o" you need to escape the '-'.

Try:

man mount | grep "\-o"

Mount: could not find any free loop device

Take a look and see if there are any mounts using any of the above loopback devices. You can use the mount command to see this:

$ mount

If they are mounted, they you'll likely need to unmount (umount) them prior to getting losetup -d <loopdevice> to detaching them.

$ umount /dev/some/mount

As to if it's safe or not, that really depends on what these are being used for. I'd probably hold off till I had a better grasp of what these loop devices are for, before I started unmounting them. Just a guess but they might have something to do with an encrypted drive.

Therefore I'd create another one just to be safe.

making another loop device

Here are the steps:

$ sudo mknod -m640 /dev/loop8 b 7 8

-m640 define the permission of the device
/dev/loop8 define the name of the device
b for the creation of the special block device
7 8 the number 7 AND 8 define the MAJOR AND the MINOR

Check if the loop is created:

$ ls -l /dev/loop8
brw-r----- 1 root root 7, 8 Oct 3 14:54 /dev/loop8

Now set ownership on the device:

$ sudo chown root:disk /dev/loop8

References

Howto create Loop Device on Linux