US 7,484,208 B1Granted

Virtual machine migration

OwnerMichael Nelsoninventor

Life of this patent

Estimating the term…

Loading patent…

Abstract

A source virtual machine (VM) hosted on a source server is migrated to a destination VM on a destination server without first powering down the source VM. After optional pre-copying of the source VM's memory to the destination VM, the source VM is suspended and its non-memory state is transferred to the destination VM; the destination VM is then resumed from the transferred state. The source VM memory is either paged in to the destination VM on demand, or is transferred asynchronously by pre-copying and write-protecting the source VM memory, and then later transferring only the modified pages after the destination VM is resumed. The source and destination servers preferably share common storage, in which the source VM's virtual disk is stored; this avoids the need to transfer the virtual disk contents. Network connectivity is preferably also made transparent to the user by arranging the servers on a common subnet, with virtual network connection addresses generated from a common name space of physical addresses.

Claims4

Dependent claims

In a networked system of computers, including a source computer and a destination computer and a source virtual machine (VM) installed on the source computer, a virtualization method for migrating the source VM to a destination VM, the method comprising:

pre-copying source VM memory to the destination VM;
suspending execution of the source VM;
transferring non-memory source VM state information to the destination VM, wherein the pre-copying of source VM memory is done before transferring the non-memory source VM state information;
running the destination VM from the transferred non-memory source VM state;
and
after transferring the non-memory source VM state information, retransferring to the destination VM one or more units of the source VM memory that the source VM has modified during the interval between when the memory units were pre-copied to the destination VM and when the non-memory source VM state information was transferred;
wherein the step of pre-copying the source VM memory to the destination VM includes:
before transferring non-memory source VM state information to the destination VM, pre-copying a first set of source VM memory units to the destination VM;
tracking modifications by the source VM of source VM memory units after the pre-copying step;
and
iteratively transferring to the destination VM remaining non-transferred source VM memory units, as well as modified VM memory units;
and
further including repeating the step of iteratively transferring remaining non-transferred source VM memory units and modified VM memory units until the number of source VM memory units not yet transferred with their most current contents is less than a threshold value, and then transferring all such remaining memory units after the destination VM begins running.

10 more elements

Dependencies are inferred from the claim text.