Abstract: A first RAID module is added to a first RAID controller and a second RAID module is added to a second RAID controller. An array of physical disks is partitioned into two partitions across the array of physical disks. The first partition is assigned to the first RAID module and the second partition is exposed to the second RAID module. Each of the RAID modules exposes their respective partitions to their associated RAID controller as a single array. Each RAID module further receives I/O from its respective RAID controller, and translates the I/O to access its associated partition.

Abstract: Disclosed herein is an enhanced volume manager (VM) for a storage system that accelerates input/output (I/O) performance for random write operations to a striped disk array using parity. More specifically, various implementations are directed to accelerating “random writes” (writes comprising less than a complete stripe of data) by consolidating several random writes together to create a “sequential write” (a full-stripe write) to eliminate one or more read operations and/or increase the volume of new/updated data stored for each write operation. Several such implementations comprise functionality in the VM (volume manager) for identifying random write I/O requests, queuing them locally in a journal, and then periodically flushing the journal to the disk array as a sequential write request.

Abstract: Disclosed is a policy-based I/O dispatcher that intercepts I/O requests from several individual volumes made to a shared storage system (such as a RAID array) and manages these I/O requests so that no single volume monopolizes the I/O bandwidth and excludes the other volumes from timely completing their own I/O requests. Also disclosed are a plurality of attributes that may be assigned to each volume sharing a disk array to effectively manage the sharing of the disk array among the volumes. The I/O policy manager may handle I/O requests from several sources including volume-based iSCSI I/O requests as well as the file-share-based XFS I/O requests.

Abstract: A RAID module for a RAID controller that includes a thin RAID layer and a thin disk layer. The thin RAID layer sits between an operating system layer and a RAID stack, and intercepts and fields requests and I/Os made the between operating system and the RAID stack. The thin disk layer sits between the RAID stack and the disks that comprise the array, and intercepts and fields requests and I/Os made between the RAID stack and the array. The module may maintain a bitmap with an entry corresponding to each stripe of the array. When the module detects that a stripe has zero data, the entry in the bitmap for the stripe is set to 0. When the module detects that data has been written to a stripe, the entry in the bitmap for the stripe is set to 1.

Abstract: Technologies are described for implementing a default migration mechanism in a storage system containing multiple tiers of storage with each tier having different cost and performance parameters. Data that is accessed more frequently can be migrated toward higher performance storage tiers while data that is accessed less frequently can be migrated towards lower performance storage tiers. Default migration behavior can be overridden by user-specified values for tier age residency policy, demotion policy, tier occupancy of volumes, and tier assignment. Data migration can be paused by the user and resumed by the user.

Abstract: Technologies are described for implementing a default migration mechanism in a storage system containing multiple tiers of storage with each tier having different cost and performance parameters. Data that is accessed more frequently can be migrated toward higher performance storage tiers while data that is accessed less frequently can be migrated towards lower performance storage tiers. Default migration behavior can be overridden by user-specified values for tier age residency policy, demotion policy, tier occupancy of volumes, and tier assignment. Data migration can be paused by the user and resumed by the user.

Abstract: Technologies are described for implementing a default migration mechanism in a storage system containing multiple tiers of storage with each tier having different cost and performance parameters. Data that is accessed more frequently can be migrated toward higher performance storage tiers while data that is accessed less frequently can be migrated towards lower performance storage tiers. Default migration behavior can be overridden by user-specified values for tier age residency policy, demotion policy, tier occupancy of volumes, and tier assignment. Data migration can be paused by the user and resumed by the user.

Abstract: A first RAID module is added to a first RAID controller and a second RAID module is added to a second RAID controller. An array of physical disks is partitioned into two partitions across the array of physical disks. The first partition is assigned to the first RAID module and the second partition is exposed to the second RAID module. Each of the RAID modules exposes their respective partitions to their associated RAID controller as a single array. Each RAID module further receives I/O from its respective RAID controller, and translates the I/O to access its associated partition.

Abstract: 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.

Abstract: 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.

Abstract: A RAID bad block module is added to a RAID controller. The bad block module intercepts bad block errors and marks them in a bad block table. When a bad block error is intercepted the bad block module logs the error and determines, based on the error and previously received errors logged in the table, whether the RAID controller can handle the error without failing the entire array. If so, the bad block module passes the error to the RAID controller. Else, the bad block module passes the error to an application or operating system where it is handled like any other disk error. Thus, instead of failing the entire array, the bad block errors are dealt with by the operating system.

Abstract: 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.