Live operating system update mechanisms

1. A method, in a data processing system comprising a processor and a memory, for performing a live update of an operating system, the method comprising:

receiving an update to an operating system;

cloning an original root volume group associated with an operating system instance executing in a first logical partition of the data processing system to generate a cloned root volume group for booting a second logical partition of the data processing system;

mirroring the original root volume group associated with the operating system instance executing in the first logical partition of the data processing system to generate a mirrored root volume group in the first logical partition, wherein modifications to the original root volume group are mirrored to the mirrored root volume group;

applying the update to the cloned root volume group to generate an updated and cloned root volume group;

booting the second logical partition of the data processing system using the updated and cloned root volume group without shutting down and restarting the data processing system;

importing the mirrored root volume group into the booted second logical partition; and

migrating application instances to the booted second logical partition by restarting the application instances in the booted second logical partition using the mirrored root volume group.

2. The method of claim 1 , further comprising:

prior to importing the mirrored root volume group into the booted second logical partition, freezing application instances running in the first logical partition until the application instances are restarted in the second logical partition, wherein freezing application instances comprises preventing modifications to a root file system of the mirrored root volume group by the application instances while the application instances are frozen.

3. The method of claim 1 , further comprising:

prior to importing the mirrored root volume group into the booted second logical partition, splitting the mirrored root volume group from the original root volume group such that modifications to the original root volume group are not mirrored to the mirrored root volume group.

4. The method of claim 1 , further comprising:

applying the update to the mirrored root volume group imported into the booted second logical partition after importing the mirrored root volume group into the booted second logical partition.

5. The method of claim 4 , wherein applying the update to the mirrored root volume group is performed prior to completion of the migration of the application instances to the booted second logical partition.

6. The method of claim 4 , wherein applying the update to the mirrored root volume group is performed after completion of the migration of the application instances to the booted second logical partition.

7. The method of claim 1 , wherein the mirroring operation is performed in parallel with the cloning operation.

8. The method of claim 1 , further comprising:

storing a first data structure specifying a set of base services that cannot be migrated from the first logical partition to the second logical partition; and

identifying a set of migratable services that can be migrated from the first logical partition to the second logical partition, wherein booting the second logical partition comprises migrating the identified set of migratable services from the first logical partition to the second logical partition, wherein the set of migratable services is customized to boot the second logical partition using a minimal set of services necessary to establish a network connection with the first logical partition and receive migrated application instances.

9. The method of claim 8 , further comprising:

maintaining the first logical partition operational with the set of base services specified in the first data structure executing in the first logical partition until migration of the application instances and application data to the booted second logical partition is complete.

10. The method of claim 9 , further comprising:

asynchronously transferring the application data in memory associated with the first logical partition to memory associated with the booted second logical partition in accordance with demand paging by the migrated application instances; and

maintaining the original root volume group in the first logical partition as a fall back root volume group after asynchronous transferring of the application data is complete.