American Megatrends, Inc.

Narayanan Balakrishnan

Paresh Chatterjee

Ajit Narayanan

Anandh Mahalingam

Vijayarankan Muthirisavenugopal

Raja Jayaraman

Srikumar Subramanian

Narayanaswami Ganapathy

Jomy Jose Maliakal

Loganathan Ranganathan

Senthilkumar Ramasamy

Srinivasa Rao Vempati

Vijayarankan Muthirisavengopal

Balasubramaniam Veeranna

Methods and systems for identifying candidates for de-duplication are disclosed herein. An example system may include: a de-duplication lister that coordinates with a kernel module to identify a unit of data for de-duplication and calculates a signature of the unit of data; a de-duplication queue that manages a de-duplication queue; a de-duplication tracker that maintains a de-duplication data structure including a plurality of entries corresponding to units of data and searches the de-duplication data structure to determine whether the signature of the identified unit of data matches the signature of at least one of the entries in the de-duplication data structure; a de-duplication maintainer that reviews the entries of the de-duplication data structure and removes obsolete entries from the de-duplication data structure; and a de-duplication engine that coordinates with the kernel module to perform de-duplication operations on the de-duplication queue.

Data de-duplication for information storage systems

Technologies for eliminating duplicate data within a storage system. De-duplication may be performed done at physical chunk level, where the data is not copied or moved to different location. A logical mapping is modified using a thin de-duplication kernel module that resides between a distributed volume manager (DVM) and a logical disk (LD). De-duplication is achieved by changing pointers in the mapping to land at a physical location. De-duplication is performed as post-process feature where duplicates are identified and the duplicates are marked in the mapping table, thereby claiming free space through de-duplication. Block-level de-duplication in accordance with the above can co-exist with existing storage architectures for thin provisioning and snapshot management.

Technologies for eliminating duplicate data within a storage system. De-duplication may be performed done at physical chunk level, where the data is not copied or moved to different location. A logical mapping is modified using a thin de-duplication kernel module that resides between a distributed volume manager (DVM) and a logical disk (LD). De-duplication is achieved by changing pointers in the mapping to land at a physical location. De-duplication is performed as post-process feature where duplicates are indentified and the duplicates are marked in the mapping table, thereby claiming free space through de-duplication. Block-level de-duplication in accordance with the above can co-exist with existing storage architectures for thin provisioning and snapshot management.

Technologies are described herein for providing snapshot-assisted synchronous replication between a first storage server and a second storage server. For example, a notification is received at the second storage server that the first storage server has resumed operations following a failure. At this time, the first storage server is in a first current state and the second storage server is in a second current state. Upon receiving the notification, a common snapshot is identified between the first storage server and the second storage server. Upon identifying the common snapshot, the first storage server is rolled back from the first current state to a previous state according to the common snapshot, and upon rolling back the first storage server from the first current state to the previous state, the first storage server and the second storage server are resynchronized using the common snapshot.

Snapshot assisted synchronous replication

Technologies are described herein for providing information lifecycle management (ILM)-assisted synchronous replication between a first storage server having a first current state and a second storage server having a second current state. For example, a notification is received at the first storage server that indicates the second storage server has resumed operations following a failure that occurred at a failure time. At this time, the first storage server is in the first current state and the second storage server is in the second current state that is different than the first current state. Then, ILM data for the first storage server is retrieved, and at least one block of data on the first storage server that was accessed after the failure time is identified. After identifying the at least one block of data, the identified block of data is re-synchronized between the first storage server and the second storage server.

Information lifecycle management assisted synchronous replication

A system, method, apparatus, and computer-readable medium are described for providing redundancy in a storage system. According to one method, maps are generated and stored that define stripe patterns for storing data on the storage nodes of a storage cluster. The maps are defined such that when a new storage node is added to the cluster, no movement of data occurs between two storage nodes that existed in the cluster prior to the addition of the new storage node during re-striping, and such that the data stored on each storage node is mirrored on another storage node. Storage nodes may also be designated as an owner or a peer for each storage zone. Input/output operations received at an owner node are fielded directly and mirrored to the peer node, while input/output operations received at a peer node are redirected to the owner node for processing.

Providing redundancy in a storage system

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

A method, system, apparatus, and computer-readable medium are described for the background movement of data between nodes in a storage cluster. According to one method, exception tables are generated that include data identifying the areas on each node that need to be migrated to another node and the areas on each node that are to be migrated from another node. The exception tables may be generated in response to the failure of a node in the storage cluster or in other circumstances. A background resynchronization thread utilizes the contents of the exception tables to migrate data between the nodes of the cluster, thereby synchronizing the data stored on the nodes. Input/output operations directed to an area that is to be migrated from another node are redirected to the other node in accordance with a timeout period associated with the input/output operations.

Background movement of data between nodes in a storage cluster

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 provided for integrating a caching module into a data storage system architecture. A request to perform an I/O operation is received at the caching module from an initiator. The caching module provides a notification to a storage driver that the request will be delivered to the storage driver in the future. The storage driver then determines whether the request can be satisfied. If the storage driver determines that it will be able to satisfy the I/O request, the storage driver can optimize the allocation and placement of the I/O request before receiving the actual I/O request. When the caching module subsequently sends the actual I/O request to the storage driver, the storage driver utilizes the previously allocated space and optimized placement to perform the requested I/O operation.

Method, system, apparatus, and computer-readable medium for integrating a caching module into a storage system architecture

Technologies are described herein for providing assisted asynchronous replication between a first storage server having a first current state and a second storage server having a second current state. An instruction to roll back a first storage server from the first current state to a previous state according to a previous snapshot is received. The first storage server is then rolled back from the first current state to the previous state according to the previous snapshot. A determination is made as to whether the previous snapshot is available on a second storage server. Assistance data is then retrieved. A last consistency point common to the first storage server and the second storage server based on the assistance data is identified, where the last consistency point is at or prior to the previous snapshot. The second storage server is rolled back from the second current state to the last consistency point.

Information lifecycle management assisted asynchronous replication

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

A user interface is provided through which a user may specify a container for data recovery. In response to the specification of a container for recovery, another user interface is provided through which the user can select a consistency group or a journal file to be utilized for recovery. In response to receiving a selection of a journal file for data recovery, a user interface is provided through which a user may specify a point in time, an event, or a snapshot at which time recovery for the corresponding volume should occur. In response to receiving a selection of a consistency group for recovery, a user interface is provided through which a user may specify a snapshot performed across two or more volumes of the consistency group that should be utilized for recovery.

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Milpitas, CA, United States of America

Narayanan Balakrishnan