Failed to setup loop device: No such file or directory when docker mounts ISO/partition

When using Docker containers, if you need to use the mount command, you must start Docker in privileged mode

The way to start docker in privileged mode is to add --privileged for example docker run -it --privileged -d image name

If it is API mode, you need to add { "Privileged":true } in the HostConfig parameter

After starting docker in privileged mode, it may appear when entering into docker and using the mount command to mount some ISO or partition files

mount -o loop ./xxx.iso /mnt/cdrom
mount: ./xxx.iso: failed to setup loop device: No such file or directory

Of course, if you do not use privileged mode, using the mount command will prompt insufficient permissions

mount -t ./xxx.iso /dev/cdrom /mnt/cdrom
mount: permission denied

Let's assume we used privileged mode and encountered failed to setup loop device in case of mount

Then we need to pay attention to the following two points

1. Make sure the loop device kernel module is installed

lsmod |grep loop

If there is no output, you need to install a kernel module

modprobe loop

2. Confirm the size of the /dev and /dev/shm partitions

These two partitions usually mount tmpfs partition files. Such problems do not occur in normal physical servers or virtual servers, but are likely to occur in docker.

we need to use

df -h

Command to check the size of these two partitions

If the partition is too small , the problem of failed to setup loop device will also occur, and the author encountered this situation.

Adjustment method

mount -o size=10240M -o remount /dev
mount -o size=10240M -o remount /dev/shm

After I resize both partitions. get it

 

{{o.name}}

{{m.name}}