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To simultaneously run more file-backed virtual disks on a host, you can increase the
number of available loopback devices by adding the following option to the host's
/etc/modprobe.conf.local file.
options loop max_loop=x
where x is the maximum number of loopback devices to create.
Changes take effect after the module is reloaded.
TIP
Enter rmmod loop and modprobe loop to unload and reload the module.
In case rmmod does not work, unmount all existing loop devices or reboot the
computer.
6.15 Saving Virtual Machines
The save operation preserves the exact state of the virtual machine's memory. The op-
eration is slightly similar to hibernating a computer. The virtual machine is off, but it
can be quickly restored to its previously-saved running condition. The operation does
not make a copy of any portion of the virtual machine's virtual disk.
When saved, the virtual machine is paused, its current memory state saved to a location
you specify, and then the virtual machine is stopped. The amount of time to save the
virtual machine depends on the amount of memory allocated. When saved, a virtual
machine's memory is returned to the pool of memory available on the host.
The restore operation is used to return a saved virtual machine to its original running
state.
IMPORTANT
After using the save operation, do not boot, start, or run a virtual machine that
you intend to restore. If the virtual machine is at any time restarted before it
is restored, the saved memory-state file becomes invalid and should not be
used to restore.
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Virtualization with Xen
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