International Business Machines Corporation

James Mulcahy

Carlos Francisco Fuente

William James Scales

Graham Hunter

Geraint M North

Matthew John Fairhurst

John Mark Clifton

Colin R Jewell

Gavin Barraclough

David James Rigby

A method and system are provided for storage checkpointing in a mirrored virtual machine system. The method includes a storage controller receiving a modifying operation to storage from a virtual machine and carrying out the modifying operation in a non-destructive manner by saving the modifying operation data to a checkpointing region of storage and preserving the stored previous data state. The method also includes receiving a checkpoint notification and committing modifying operation data from the checkpointing region and releasing the stored previous data state. If a failover notification is received, the storage controller rolls back the physical storage to match a checkpoint state.

Storage checkpointing in a mirrored virtual machine system

A data processing system provides checkpoint high-available for an application in a virtualized environment with reduced network demands. An application executes on a primary host machine comprising a first virtual machine. A virtualization module receives a designation from the application of a portion of the memory of the first virtual machine as purgeable memory, where the purgeable memory can be reconstructed by the application when the purgeable memory is unavailable. Changes are tracked to a processor state and to a remaining portion that is not purgeable memory and the changes are periodically forwarded at checkpoints to a secondary host machine. In response to an occurrence of a failure condition on the first virtual machine, the secondary host machine is signaled to continue execution of the application by using the forwarded changes to the remaining portion of the memory and by reconstructing the purgeable memory.

Resource recovery for checkpoint-based high-availability in a virtualized environment

Storing defined presets for configuration of a storage controller may include providing a storage controller interface to define a preset associated with an action of the storage controller; receiving preset parameter values for the preset via the interface; validating the preset parameter values to check that the preset is valid; storing the preset within the storage controller, and creating one or more preset objects from the preset, the preset object being accessible by the storage controller at run time. The preset may include a human-readable name; an action name indicating to which associated storage controller action the preset applies, and a set of parameter name-value pairs.

Flexibly storing defined presets for configuration of storage controller

A method for mirroring virtual machines from a primary host to a secondary host. The method includes tracking changes for each of a plurality of memory pages and processor states for one or more primary host virtual machines. Responsive to an occurrence of a checkpoint, the primary host virtual machines are stopped. A determination is made if each of the memory pages is frequently changed. In response to the memory page being frequently changed, the frequently changed memory page is marked as being writeable and copied to a buffer. In response to the memory page being infrequently changed, the infrequently changed memory page is marked as being read only. The one or more primary host virtual machines are resumed. A copy of the memory pages, the buffer and changes to the processor states are transmitted to the secondary host.

Mirroring virtual machines from a primary host to a secondary host

A system and computer program product for mirroring virtual machines from a primary host to a secondary host. The system includes a processor tracking changes for each of a plurality of memory pages and processor states for one or more primary host virtual machines. Responsive to an occurrence of a checkpoint, the primary host virtual machines are stopped. A determination is made if each of the memory pages is frequently changed. In response to the memory page being frequently changed, the frequently changed memory page is marked as being writeable and copied to a buffer. In response to the memory page being infrequently changed, the infrequently changed memory page is marked as being read only. The one or more primary host virtual machines are resumed. A copy of the memory pages, the buffer and changes to the processor states are transmitted to the secondary host.

A computing system capable of handling floating point operations during program code conversion is described, comprising a processor including a floating point unit and an integer unit. The computing system further comprises a translator unit arranged to receive subject code instructions including at least one instruction relating to a floating point operation and in response to generate corresponding target code for execution on said processor. To handle floating point operations a floating point status unit and a floating point control unit are provided within the translator. These units are cause the translator unit to generate either: target code for performing the floating point operations directly on the floating point unit; or target code for performing the floating point operations indirectly, for example using a combination of the integer unit and the floating point unit. In this way the efficiency of the computing system is improved.

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Manchester, United Kingdom

James Mulcahy