Virtual machine hot cloning including freezing and unfreezing memory in a distributed network

• US 7,536,525 B2
• Filed: 11/09/2004
• Issued: 05/19/2009
• Est. Priority Date: 11/09/2004
• Status: Active Grant

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Chandrasekaran, Balasubramanian, Abels, Timothy E.
• Primary Examiner(s): Elmore; Stephen C
• Assistant Examiner(s): Ayash; Marwan
• Application Number:
  US10/984,397
• Publication Number:
  US 20060101189A1
• Time in Patent Office: 1,652 Days
• Field of Search: 711/165, 718/1
• US Class Current: 711/165
• CPC Class Codes: G06F 2009/4557 Distribution of virtual machine instances; Migration and load balancing
• CPC Class Codes: G06F 8/63 Image based installation; Cloning; Build to order
• CPC Class Codes: G06F 9/4418 Suspend and resume; Hibernate and awake

Abstract

A system and method for hot cloning in a distributed network is disclosed. In one embodiment, a method for cloning a virtual machine from a source system to a target system includes freezing writes to a storage file having storage blocks such that subsequent writes create new storage blocks for the original virtual machine. The method further including freezing writes to a memory content such that subsequent writes store in buffers. The method further including copying the memory content onto the target system wherein the copied memory content creates a clone. The method further including unfreezing the memory content by merging the writes stored in the buffers and unfreezing the writes to the storage file such that subsequent writes take place normally. The method further including configuring the clone based on the target system. The method further including creating a new storage block for any writes to the storage file whereby the new storage block is not shared.

Claims

1. A method for cloning a virtual machine from a source system to a target system in an information handling system, comprising:

freezing writes to a storage file having storage blocks of an original virtual machine residing on a distributed network such that subsequent writes create new storage blocks for the original virtual machine, the distributed network using a first pointer to designate the location of the original virtual machine within a shared storage associated with the distributed network;

freezing writes to a memory content for the original virtual machine such that subsequent writes to the frozen memory content are stored in buffers, wherein freezing writes to the memory content includes freezing all levels of memory starting with a slowest level of memory and finishing with a fastest level of memory;

copying the frozen memory content including processor state and input/output state onto the target system wherein the copied memory content creates a clone of the original virtual machine;

unfreezing the memory content of the original virtual machine by merging the writes stored in the buffers with the frozen memory content;

unfreezing the writes to the storage file such that the original virtual machine and the clone both access the storage file;

configuring the clone of the virtual machine based on unique characteristics for the clone of the original virtual machine;

creating a second pointer, the second pointer designating the location of the clone of the original virtual machine within the shared storage of the distributed network; and

creating a new storage block for any subsequent writes to the storage file whereby the new storage block is unique to the virtual machine causing the subsequent writes to the storage file.

2. The method of claim 1, wherein creating a copy of the memory content further comprises copying all levels of memory.

3. The method of claim 1, wherein configuring the clone of the virtual machine further comprises running a cloning wizard.

4. The method of claim 3, wherein the cloning wizard further comprises modifying an Internet Protocol (IP) address or a host name for the clone on the target system.

5. The method of claim 3, further comprising performing a system preparation on the clone to remove information that will remain unique to the original virtual machine.

6. The method of claim 1, further comprising finishing all active transactions prior to cloning the original virtual machine.

7. The method of claim 1, wherein the copying the memory content further comprises copying certain state information including the state of associated virtual devices to the clone of the virtual machine on the target system.

8. The method of claim 1, further comprising performing the cloning of the virtual machine in real-time.

9. An information handling system, comprising:

a distributed network including;

a plurality of processors coupled to a processor bus;

a memory coupled to the processor bus;

a shared storage system operably coupled to the processors and the memory;

the shared storage system including a target system and a source system having a virtual machine;

the virtual machine including a storage file having a plurality of storage blocks;

a first pointer designating the location of the virtual machine within the shared storage system; and

the processors operable to execute instructions for cloning the virtual machine from the source system to the target system, comprising;

freezing writes to the storage file wherein subsequent writes create new storage blocks for the virtual machine;

freezing a memory content including processor state and input/output state for the virtual machine whereby subsequent writes to the frozen memory content are placed in buffers, wherein freezing the memory content includes freezing all levels of memory starting with a slowest level of memory and finishing with a fastest level of memory;

copying the frozen memory content onto the target system to create a clone;

unfreezing the memory content of the virtual machine by merging the writes placed in the buffers with the frozen memory content;

unfreezing the writes to the storage file such that the virtual machine and the clone both access the storage file;

configuring the clone based on unique characteristics for the clone;

creating a second pointer, the second pointer designating the location of the clone within the shared storage of the distributed network; and

creating a new storage block for any subsequent writes to the storage file whereby the new storage block is unique to the virtual machine causing the subsequent write to the storage file.

10. The information handling system of claim 9, wherein creating a copy of the memory content further comprises copying all levels of memory (cache level and memory registers).

11. The information handling system of claim 9, wherein copying comprises using a copy on write command.

12. The information handling system of claim 9, wherein the information handling system comprises a distributed network system.

13. The information handling system of claim 9, wherein the instructions further comprise completing active transactions prior to cloning the virtual machine.

14. A tangible computer-readable storage medium having computer-executable instructions stored therein, the instructions for performing a method of cloning a virtual machine from a source system to a target system in an information handling system, comprising:

instructions for stopping writes to a storage file having storage blocks of an original virtual machine and freezing writes to a memory content for the original virtual machine such that subsequent writes to the frozen memory content are stored in buffers;

instructions for copying the frozen memory content such that copying starts with a fastest level of memory and finishes with a slowest level of memory onto the target system wherein the copied memory content creates a clone of the original virtual machine;

following the instructions for copying, instructions for unfreezing the writes to the storage file and unfreezing the memory content of the original virtual machine by merging the writes stored in the buffers with the frozen memory content;

instructions for sharing the storage file between the original virtual machine and the clone of the original virtual machine;

instructions for configuring the clone of the virtual machine based on unique characteristics for the clone of the virtual machine;

instructions for creating a pointer, the pointer designating the location of the clone of the virtual machine within the information handling system; and

instructions for creating a new storage block for any subsequent writes to the storage file whereby the new storage block is unique to the virtual machine causing the subsequent write to the storage file.

15. The tangible computer-readable storage medium of claim 14, further comprising instructions for performing a system preparation on the clone to remove information that will remain unique to the original virtual machine.

16. The tangible computer-readable storage medium of claim 14, wherein the levels of memory include cache levels of memory and memory registers.

17. The tangible computer-readable storage medium of claim 14, wherein the target system may be the same as the source system.