American Megatrends, Inc.

Lsi Corporation

Raja Jayaraman

Paresh Chatterjee

Narayanan Balakrishnan

Ajit Narayanan

Jomy Jose Maliakal

Anandh Mahalingam

Narayanaswami Ganapathy

Loganathan Ranganathan

Srikumar Subramanian

James A Rizzo

Vinu Velayudhan

Rakesh Chandra

Phillip V Nguyen

Venugopal Reddy Mallavaram

Abhishek Khare

Rajesh Arivoli

Technologies for providing recovery point review within a continuous data protection system can support a data storage operator in a data recovery procedure. A snapshot image can be chosen that was made prior to a data loss event. A new writable snapshot can be created from this logged snapshot. The new writeable snapshot can become the target for recovering the data volume. Review can be performed in a forward direction by reading a journal of I/O operations that have occurred since the prior snapshot was made. Review can be performed in a backward direction by deriving a dirty data list of changes made to the data volume and then removing the changes as requested. The operator can continue forward and backward review operations to refine the selected recovery point. Upon establishing the desired recovery point, the new writable snapshot can be committed, or rolled back, onto the data storage volume.

Data recovery point review in a continuous data protection system

Systems and methods for maintaining data consistency across mirrored storage nodes. Data consistency may be maintained in networked storage environments using a timestamp of an I/O in the primary and secondary servers (also referred to as nodes) in synchronous replication to re-synchronize the data efficiently, without much performance drop and while reducing the memory footprint. According to an aspect presented herein, data consistency is maintained in a mirror node by timestamping the I/O for a volume's logical territory in both the primary and secondary nodes. The timestamp acts as a watermark. Thus, whenever a disaster or failure occurs, the watermark point determines the re-synchronization point.

Use of timestamp logic in synchronous replication

Methods and structure for load balancing of background tasks between storage controllers are provided. An exemplary active storage controller comprises a front-end interface that receives host Input/Output (I/O) requests directed to a logical volume, a back-end interface that couples with one or more of storage devices provisioning the logical volume, and a control unit. The control unit processes the host I/O requests directed to the logical volume, identifies a background processing task distinct from the host I/O requests and related to the logical volume, and assigns the background processing task to a passive storage controller for processing.

Methods and structure for load balancing of background tasks between storage controllers in a clustered storage environment

Technologies are described herein for providing efficient backup of multiple versions of a data file using data de-duplication. A CDP module copies blocks of data of a specific block size from a current version of the data file to a master file maintained in a backup location for the data file. Only blocks of data not matching a unique data block already in the master file are copied. The CDP module then creates an anterior file in the backup location for the current version of the data file containing an ordered list of references to the unique data blocks in the master file. The order of the list of references is based on the order of occurrence of each unique data block in the modified version of the data file. Finally, the CDP module creates a posterior file in the backup location for the current version of the data file containing any remaining block of data in the data file that is less than the specific block size.

Efficient backup of multiple versions of a file using data de-duplication

Techniques for maintaining mirrored storage cluster data consistency can employ write-intent logging. The techniques can be scaled to any number of mirror nodes. The techniques can keep track of any outstanding I/Os, data in caches, and data that has gone out of sync between mirrored nodes due to link failures. The techniques can ensure that a power failure on any of the storage nodes does not result in inconsistent data among the storage nodes. The techniques may keep track of outstanding I/Os using a minimal memory foot-print and having a negligible impact on the I/O performance. Properly choosing the granularity of the system for tracking outstanding I/Os can result in a minimal amount of data requiring transfer to synchronize the mirror nodes. The capability to vary the granularity based on physical and logical parameters of the storage volumes may provide performance benefits.

Maintaining data consistency in mirrored cluster storage systems using bitmap write-intent logging

Technologies for providing block-level continuous data protection can operate without additional external devices. I/O operations to a storage volume may be logged to a sequential journal volume. The logging can occur in parallel to the I/O operation thereby having little, or no, impact on the performance of the storage system. Previous data need not be backed up; instead only new I/O operations may be recorded in the journal or log. Snapshot events may also be recorded to the logging journal. When a volume is to be recovered, a snapshot can be mounted and I/O operations after the snapshot creation, but prior to the recovery point, can be played back onto the snapshot. Operators may be provided with a flexible mechanism for reviewing and recovering data after a data loss. Using snapshots and I/O journals, a volume can be rolled back to a desired point nearly instantaneously.

Continuous data protection journaling in data storage systems

Techniques for maintaining mirrored storage cluster data consistency on systems with two-node, highly available storage solutions can employ an initiator-side agent operable to prevent split-brain scenarios. Split brain syndrome can be avoided, information identifying changes of synchronization states can be maintained, and both graceful and ungraceful shutdowns (or failures) of either one of the nodes or of the intelligent initiator itself can be mitigated. Technology presented herein supports load balancing and hot failover/failback in systems that may feature redundant network connectivity. Moreover, a method is supported for communicating storage cluster status between the storage nodes and the initiator.

Two-node high availability cluster storage solution using an intelligent initiator to avoid split brain syndrome

Technologies are described herein for skipping snapshots during a snapshot replication process in order to maintain an established recovery point objective. A first snapshot is selected after a previously replicated snapshot. A creation time of the first snapshot is retrieved. A difference between a current time and the creation time of the first snapshot is computed. A determination is made as to whether the difference is less than a recovery point objective. If the difference is less than a recovery point objective, then the first snapshot is replicated in the snapshot replicated process. If the difference is not less than a recovery point objective, then the first snapshot is skipped through the snapshot replication process.

Asynchronous replication by tracking recovery point objective

Technologies are described herein for providing a power-save mode of operation for a continuous data protection ('CDP') process. A CDP module executing on a computer detects when the computer is operating under battery power, and enters a power-save mode of operation. In the power-save mode, the CDP module monitors the state of the battery and restricts the CDP process based on a set of configuration settings specified for one of a number of zones, where each zone defines an upper and lower thresholds for a level of charge of the battery. If external power is restored to the computer, the CDP module restores the normal mode of operation for the CDP process.

Power save mode operation for continuous data protection

Techniques for maintaining mirrored storage cluster data consistency on systems with write back cache can employ write-intent logging and periodic log clearing. The techniques can track any outstanding I/Os, data in caches, and data that has gone out of sync between mirrored nodes due to link failures. The techniques can ensure that a power failure on any of the storage nodes does not result in inconsistent data among the storage nodes. The techniques can use gate bitmaps to log outstanding I/Os. The gate bitmaps may be periodically cleared. The clearing period may be selected as to allow enough time for all caches to be flushed and for all synchronizing I/Os to complete. Efficient queuing of I/O requests in conjunction with the efficient operation of multiple gate bitmaps can reduce performance impacts of the gating or logging operations.

Maintaining data consistency in mirrored cluster storage systems with write-back cache

Boot consolidation based on writeable volume snapshots can leverage flexible mappings of snapshot dependencies. Such flexible mappings can be established by relating sequence numbers associated with various volume snapshots and can provide for an arbitrarily complex mapping to support a potentially unlimited number of writable snapshots in potentially any dependency configuration. Additionally, the pinning of volumes can provide support for chains of snapshots to depend from snapshots within other chains of snapshots. Merge agents can operate with writable snapshots and boot consolidation to provide system-wide updates where security patches, upgrades, and application software may be applied to a group of servers or a group of users in an efficient fashion.

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Fremont, CA, United States of America

Raja Jayaraman