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 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.

Abstract: Technologies are described for implementing a migration mechanism in a storage system containing multiple tiers of storage with each tier having different cost and performance parameters. Access statistics can be collected for each territory, or storage entity, within the storage system. 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. The placement of data may be governed first by the promotion of territories with higher access frequency to higher tiers. Secondly, data migration may be governed by demoting territories to lower tiers to create room for the promotion of more eligible territories from the next lower tier. In instances where space is not available on the next lower tier, further demotion may take place to an even lower tier in order to make space for the first demotion.

Abstract: 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.

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: 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: 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 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.

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.

Abstract: Technologies are provided for reclaiming a file system coupled to a block device. In these technologies, a dummy file is created. The dummy file is expanded to fill a volume in the block device. A mapping of the dummy file to locations in the volume is retrieved. When the mapping of the dummy file to the locations in the volume is retrieved, corresponding space in the volume is reclaimed. This space may include the locations in the volume corresponding to the mapping of the dummy file. When this space in the volume is reclaimed, the dummy file is deleted.

Abstract: Technologies are described herein for caching variably sized access control lists (ACLs) in a data storage system utilizing page object caching. A request to access a file is received. An inode number of the requested file is identified. A hash key based on the inode number and a predefined hash value is determined. A determination is made as to whether the hash key is contained in a hash list. In response to determining that the hash key is contained in the hash list, access to a page object in the memory is provided. The page object contains an access control list (ACL) associated with the requested file. The ACL is retrieved from the page object.

Abstract: Technologies are described herein for accelerating the boot process of client computers by consolidating client-specific boot data in a data storage system. Boot statistics are collected for a number of client computers booting from virtual storage volumes provided by the data storage system. The boot statistics are analyzed to identify client-specific boot data stored on each of the virtual storage volumes, and the client-specific boot data is consolidated and copied into contiguous regions of a single, consolidated boot volume in the data storage system. Requests for read operations from the client computers for the client-specific boot data are then redirected to the consolidated boot volume, increasing boot performance for the client computers.

Abstract: Technologies are described herein for providing networked RAID in a virtualized storage cluster. The storage capacity of a storage cluster having two or more storage nodes is organized into tiers. A portion of the available storage capacity is allocated to one tier that is organized using chained declustering. Another portion of the available storage capacity is allocated to another tier that is organized using a networked RAID configuration. The storage cluster monitors the frequency at which data in the storage cluster is accessed. Frequently used data that is stored in the network RAID-configured tier is promoted to the chained declustered-configured tier. Infrequently used data that is stored in the chained declustered-configured tier is demoted to the network RAID-configured tier.

Abstract: A method, system, apparatus, and computer-readable medium are provided for performing read-ahead operations for sequential read operations. A method includes maintaining a bitmap including a plurality of bits, each bit corresponding to a sector of the disk cache and containing data indicating whether the corresponding sector is valid and can be used to satisfy read requests. The method includes receiving a request to read a sector of the disk cache, and in response, identifying a bit in the bitmap that corresponds to the requested sector. Further, the method includes determining whether the disk cache contains valid data for a sector previous to the requested sector by examining a bit in the bitmap previous to the bit that corresponds to the requested sector, and in response, reading sequentially into the disk cache sectors of the disk cache corresponding to bits in the bitmap following the bit corresponding to the requested sector.

Abstract: Technologies are described for implementing a migration mechanism in a data storage system containing multiple tiers of storage with each tier having different cost and performance parameters. Access statistics can be collected for each territory, or storage entity, within the storage system. 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. Each tier can be associated with a range of ILM statistics referred to as the bucket for that tier. A pivot table may be provided that relates the tiers and the buckets. Operations on the pivot table can provide counts of how many territories may be promoted or demoted between any two pairs of tiers.

Abstract: 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.

Abstract: Technologies for eliminating duplicate data provisions within a storage system supporting boot consolidation can efficiently identify duplicate data provisions within a data storage system and eliminate duplication by remapping duplicate provisions to point to the same physical storage space. Signatures of provisions within a storage system may be calculated and compared. Matching, or collisions, within the list of provision signatures can indicate candidate provisions for de-duplication. De-duplication territories may be provided as an indirect mapping mechanism in support of the remapping of duplicated provisions. Access statistics associated with provisions within a storage system may be collected. Access statistics can support the scheduling of de-duplication processes. Data de-duplication can support substantial storage space consolidation and significantly improve caching efficiency within a data storage system.

Abstract: Technologies are described herein for accelerating the boot process of client computers by consolidating client-specific boot data in a data storage system. Boot statistics are collected for a number of client computers booting from virtual storage volumes provided by the data storage system. The boot statistics are analyzed to identify client-specific boot data stored on each of the virtual storage volumes, and the client-specific boot data is consolidated and copied into contiguous regions of a single, consolidated boot volume in the data storage system. Requests for read operations from the client computers for the client-specific boot data are then redirected to the consolidated boot volume, increasing boot performance for the client computers.

Abstract: Technologies are described herein for boot caching to accelerate boot access in a data storage system providing boot consolidation. Boot caching may be provided to improve boot access for multiple clients concurrently booting from a common storage server. Boot statistics may be collected per user or client. The boot statistics can determine common patterns within the boot procedures of the clients and may be used to compute boot caching tables. These tables may then be used during boot caching to accelerate booting of clients. A boot caching mechanism can be implemented to support improved booting performance by caching data blocks common to multiple booting volumes. This approach can leverage the condition that much of the data loaded by clients at boot time may be substantially identical, because booting can involve loading the same operating system components into each client.

Abstract: Technologies for eliminating duplicate data within a storage system can efficiently identify and eliminate duplication by remapping borrower regions to share physical storage space with lender regions. Block-level de-duplication can co-exist with storage architectures for thin provisioning and snapshot management. Lending maps can track redirected pointers from borrower regions to shared physical storage from lender regions. The lending maps can track the freed status of regions to support efficient write I/O operations without defaulting to unnecessary read-modify-write cycles to complete data writes. Redundancy of de-duplicated data can maintain one or more copies to support recovery from media errors. Candidate regions for de-duplication can be identified by monitoring the times and patterns of data access operations. A sampled mechanism for calculating and comparing signatures of data blocks can support the efficient identification of duplicated data within the storage system.