Planning a reliable migration in a limited stability virtualized environment

1. A computer-implemented method for reliably migrating a virtual machine (VM), the method comprising:

receiving overhead and reliability factors for hosts in a hosting fabric;

determining a plurality of viable migration paths for migrating a source VM from a source host to a target host in the hosting fabric, wherein the migration is accomplished through a series of migration phases, wherein a phase involves migration of the source VM from one host to another host in a migration path;

determining total overhead costs associated with one or more migration paths; and

selecting a migration path from among said plurality of viable migration paths according to the overhead costs and reliability factors, such that reliability goals defined for the migration of the source VM are best satisfied considering the overhead associated with the selected migration path,

wherein the reliability of the migration over the selected migration path is monitored and controlled by dynamically allocating and de-allocating a plurality of replicas of the source VM on one or more hosts in the migration fabric, wherein the plurality of replicas of the source VM run concurrently with the source VM to satisfy the reliability goals defined for the migration of the source VM over multiple hops in the selected migration path, until the source VM is successfully migrated to the target host, and

wherein number of replicas of the source VM running concurrently during the migration is increased when a migration goal requires more stable migration environment, and wherein the number of replicas of the source VM running concurrently during the migration is decreased when the migration goal requires less stable migration environment.

2. The method of claim 1 , wherein the selected migration path provides the least costly migration option.

3. The method of claim 1 , wherein the selected migration path provides the most reliable migration option.

4. The method of claim 1 , wherein the selected migration path provides the combined least costly and most reliable migration option.

5. The method of claim 1 , wherein the migration goal for the migration of the source VM is defined according to a minimum reliability threshold.

6. The method of claim 5 , wherein the number of replicas for the source VM during the migration is adjusted to meet the migration goal.

7. The method of claim 1 , wherein the replicas of source VM are synchronized with the source VM during the migration.

8. The method of claim 1 , further comprising:

selecting an alternate migration path, in response to determining that the selected migration path is no longer viable.

9. A system for reliably migrating a virtual machine (VM) from a source host to a target host, the system comprising:

a logic unit for receiving overhead and reliability factors for hosts in a hosting fabric;

a logic unit for determining a plurality of viable migration paths for migrating a source VM from a source host to a target host in the hosting fabric, wherein the migration is accomplished through a series of migration phases, wherein a phase involves migration of the source VM from one host to another host in a migration path;

a logic unit for determining total overhead costs associated with one or more migration paths; and

a logic unit for selecting a migration path from among said plurality of viable migration paths according to the overhead costs and reliability factors, such that reliability goals defined for the migration of the source VM are best satisfied considering the overhead associated with the selected migration path,

wherein the reliability of the migration over the selected migration path is monitored and controlled by dynamically allocating and de-allocating a plurality of replicas of the source VM on one or more hosts in the migration fabric, wherein the plurality of replicas of the source VM run concurrently with the source VM to satisfy the reliability goals defined for the migration of the source VM over multiple hops in the selected migration path, until the source VM is successfully migrated to the target host, and

wherein number of replicas of the source VM running concurrently during the migration is increased when a migration goal requires more stable migration environment, and wherein the number of replicas of the source VM running concurrently during the migration is decreased when the migration goal requires less stable migration environment.

10. The system of claim 9 , wherein the selected migration path provides the least costly migration option.

11. The system of claim 9 , wherein the selected migration path provides the most reliable migration option.

12. The system of claim 9 , wherein the selected migration path provides the combined least costly and most reliable migration option.

13. The system of claim 9 , wherein the migration goal for the migration of the source VM is defined according to a minimum reliability threshold.

14. The system of claim 13 , wherein the number of replicas for the source VM during the migration is adjusted to meet the migration goal.

15. The system of claim 9 , further comprising:

a logic unit for selecting an alternate migration path, in response to determining that the selected migration path is no longer viable.

16. A computer program product comprising a non-transitory data storage medium having a computer readable program, wherein the computer readable program when executed on a computer causes the computer to:

receive overhead and reliability factors for hosts in a hosting fabric;

determine a plurality of viable migration paths for migrating a source VM from a source host to a target host in the hosting fabric, wherein the migration is accomplished through a series of migration phases, wherein a phase involves migration of the source VM from one host to another host in a migration path;

determine total overhead costs associated with one or more migration paths; and

select a migration path from among said plurality of viable migration paths according to the overhead costs and reliability factors, such that reliability goals defined for the migration of the source VM are best satisfied considering the overhead associated with the selected migration path,

wherein the reliability of the migration over the selected migration path is monitored and controlled by dynamically allocating and de-allocating a plurality of replicas of the source VM on one or more hosts in the migration fabric, wherein the plurality of replicas of the source VM run concurrently with the source VM to satisfy the reliability goals defined for the migration of the source VM over multiple hops in the selected migration path, until the source VM is successfully migrated to the target host, and

wherein number of replicas of the source VM running concurrently during the migration is increased when a migration goal requires more stable migration environment, and wherein the number of replicas of the source VM running concurrently during the migration is decreased when the migration goal requires less stable migration environment.

17. The computer program product of claim 16 , wherein the selected migration path provides the least costly migration option.

18. The computer program product of claim 16 , wherein the selected migration path provides the most reliable migration option.