Abstract: An example computer-implemented method for restoring data consistency in a RAID array can include detecting failure of a disk of the RAID array, maintaining tracking information for write input/output (“I/O”) operations that effect a data block or a parity block stored on the failed disk, re-commissioning the failed disk and re-synchronizing the RAID array using the tracking information. The tracking information can be used to restore consistency to at least one of the data stripes. For example, the RAID array can store data in one or more data stripes, where each data stripe has a plurality of data and parity blocks. Additionally, the data stripes to which consistency is restored can include a data block or a parity block that is stored on the re-commissioned disk and that is effected by the write I/O operations and stored on the re-commissioned disk.

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: An example method for using a plurality of SSDs as a caching medium in a data storage system can include splitting the SSDs into a plurality of cache regions, maintaining a first cache region of the SSDs as a read cache and maintaining a second cache region of the SSDs as a write cache. Additionally, read data can be stored by striping the read data across the SSDs in the first cache region, and dirty write data can be stored by mirroring the dirty write data across the SSDs in the second cache region. The computer-implemented method can also include dynamically adjusting a size of at least one of the first and second cache regions of the SSDs based on an input/output (“I/O”) load of the data storage system.

Abstract: An example computer-implemented method for performing efficient patrol read operations in a storage system including a plurality of disks organized in a RAID array can include determining an I/O load on the storage system, identifying at least one portion of an available storage capacity containing valid data and reading the portion of the available storage capacity containing the valid data. Optionally, the portion of the available storage capacity containing the valid data is the only portion read during the patrol read operations. The method can also include determining whether a medium error exists in the portion of the available storage capacity containing the valid data. If a medium error exists, the method can include fixing the medium error. Additionally, the above operations can optionally be performed only when the I/O load on the storage system is less than a predetermined threshold.

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: 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.