Using master file template area to increase density of virtual machines in a computer system

A computer useable non-transitory storage medium having computer executable program logic stored thereon for executing on a processor, the program logic implementing the steps of:

• launching a plurality of Virtual Machines in a computing system having a host operating system (OS) running on a hardware processor;
• based on knowledge of which file in the VM and in the host OS is owned by which component, identifying identical files in multiple guest OSes in the Virtual Machines and in the host OS;
• using a content of at least one file of the identical files of the host OS as a shared file;
• using a re-direct, providing access to the shared file when any Virtual Machine attempts to access its private file;
• and
• using copy-on-write, making a copy of the shared file if the Virtual Machine attempts to modify the shared file, and placing a copy of the shared file in a private area of the corresponding Virtual Machine,
• wherein files of one of the Virtual Machines are used as a master template, and the master template includes the at least one file of the host OS to which attempts to access a corresponding shared file by other Virtual Machines are redirected.

A system for migrating an execution environment to a new platform hardware or a new virtual platform, the system comprising:

• a processor;
• a memory;
• and
• a computer code loaded into the memory and executed on the processor for implementing the steps of:
• launching a plurality of Virtual Machines in a computing system having a host operating system (OS) running on a hardware processor;
• based on knowledge of which file in the VM and in the host OS is owned by which component, identifying identical files in multiple guest OSes in the Virtual Machines and in the host OS;
• using a content of at least one file of the identical files of the host OS as a shared file;
• using a re-direct, providing access to the shared file when any Virtual Machine attempts to access its private file;
• and
• using copy-on-write, making a copy of the shared file if the Virtual Machine attempts to modify the shared file, and placing a copy of the shared file in a private area of the corresponding Virtual Machine,
• wherein files of one of the Virtual Machines are used as a master template, and the master template includes the at least one file of the host OS to which attempts to access a corresponding shared file by other Virtual Machines are redirected.

A system for managing files of Virtual Machines, the system comprising:

• an operating system running on a hardware processor in operating system space;
• a plurality of Virtual Machines running in user space;
• a master copy of at least some files of least one Virtual Machine maintained by the operating system,
• wherein the at least some files have been flagged as identical files in multiple guest OSes in the Virtual Machines and in the host OS based on knowledge of which file in the VM and in the host OS is owned by which component;
• and
• a software component running in operating system space that compares contents of the files of the Virtual Machines to the master copy, and for those files that have the same contents, replaces the files of the Virtual Machine with links to the master copy files,
• wherein the master template includes user application files and host OS files such that attempts to access a corresponding shared file by other Virtual Machines are redirected to the master template.