American Megatrends Assigned Two Patents

Computer-readable medium for implementing caching in storage system
American Megatrends, Inc., Norcross, GA, has been assigned a patent (8,549,230) developed by four co-inventors for a “method, system, apparatus, and computer-readable medium for implementing caching in a storage system.”

The co-inventors are Paresh Chatterjee, Srikumar Subramanian, Fremont, CA, Srinivasa Rao Vempati, Milford, MA, and Suresh Grandhi, Fremont, CA.

The abstract of the patent published by the U.S. Patent and Trademark Office states: “A method, system, apparatus, and computer-readable medium are provided for implementing caching in a storage system. According to aspects of the invention, a cache module is provided that utilizes cache lines sized according to a snapshot chunk size or an allocation unit size. The cache module utilizes cache header data structures corresponding to cache lines, each of which is assigned a device and logical block access range when active. The active headers are arranged in a set of hash queues. A free queue corresponds to the list of unused cache headers and a dirty queue corresponding to a list of unflushed cache headers. The cache header contains sector-level bitmaps of the cache line, specifying on a per sector granularity the bits that are dirty and valid. Flushing is performed by copying the dirty bitmap into a temporary memory location and flushing the bits set in it, while resetting the dirty bitmap and allowing writes to it. A read-ahead algorithm is used to perform read-ahead operations only in the event of a sequential read.”

The patent application was filed on July 7, 2009 (12/498,599).

Maintaining data consistency in mirrored cluster storage systems
using bitmap write-intent logging
American Megatrends, Norcross, GA, has been assigned a patent (8,595,455) developed by four co-inventors for “maintaining data consistency in mirrored cluster storage systems using bitmap write-intent logging.”

The co-inventors are Paresh Chatterjee, Fremont, Narayanan, Fremont, CA, Narayanan Balakrishnan, Milpitas, CA, and Raja Jayaraman, Fremont, CA.

The abstract of the patent published by the U.S. Patent and Trademark Office states: “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.”

The patent application was filed on Sept. 23, 2011 (13/242,259).