Unable to start SolusVM Xen VPS: Failed to find an unused loop device

Symptoms

Unable to start SolusVM Xen VPS - in SolusVM > Virtual Servers > VPS > Reboot (Debug) the following is shown:

SVM_ERROR: libxl: error: libxl_exec.c:118:libxl_report_child_exitstatus: /etc/xen/scripts/block add [9546] exited with error status 1
libxl: error: libxl_device.c:1150:device_hotplug_child_death_cb: script: Failed to find an unused loop device
libxl: error: libxl_create.c:1176:domcreate_launch_dm: unable to add disk devices

Cause

Xen node ran out of loop devices that are used for mounted images.

Resolution

Increase the number of available loop devices:

1. Access the affected SolusVM Xen node over SSH.

2. Create file /etc/modprobe.d/local-loop.conf:

   # echo "options loop max_loop=64" > /etc/modprobe.d/local-loop.conf

3. Reboot the node.