Abstract: A system and method for improving storage system operation is disclosed. A storage system includes a first tier with high-performance redundancy and a second tier with capacity efficient redundancy. The first tier and the second tier are built from the same storage devices in a storage pool so each storage device includes both the first and second tiers. The storage system stores write data initially to the first tier. When demand for the data falls below a threshold, the storage system migrates the write data to the second tier. This is done by changing the mapping of underlying physical locations on the storage devices where the write data is stored so that the underlying physical locations are logically associated with the second tier instead of the first tier. After remapping, the storage system also computes parity information for the migrated write data and stores it in the second tier.

Abstract: A system and method for improving storage system operation is disclosed. A storage system includes a first tier with high-performance redundancy and a second tier with capacity efficient redundancy. The first tier and the second tier are built from the same storage devices in a storage pool so each storage device includes both the first and second tiers. The storage system stores write data initially to the first tier. When demand for the data falls below a threshold, the storage system migrates the write data to the second tier. This is done by changing the mapping of underlying physical locations on the storage devices where the write data is stored so that the underlying physical locations are logically associated with the second tier instead of the first tier. After remapping, the storage system also computes parity information for the migrated write data and stores it in the second tier.

Abstract: Methods and structure for online migration of data in a storage system comprising a plurality of storage devices. The method comprises redefining a volume of a storage system mapped according to a first mapping structure by defining a second mapping structure. The method further comprises quiescing processing of host I/O requests directed to the volume and transitioning control of the volume from a first to a second volume manager so as to utilize the benefits of the second mapping structure. The method further comprises commencing processing of host I/O requests directed to the volume wherein the volume is mapped according to the second mapping structure. The method further comprises migrating, via the second volume manager, volume data to any of a plurality of storage devices of the system, online, without interrupting processing of host I/O requests directed to the volume. This migrates volume data without significant downtime or wasted space.

Abstract: A system and method for improving the distribution of data extent allocation in dynamic disk pool systems is disclosed. A storage system includes a storage controller that calls a hashing function to select storage devices on which to allocate data extents when such is requested. The hashing function takes into consideration a weight associated with each storage device in the dynamic disk pool. Once a storage device is selected, the weight associated with that storage device is reduced by a predetermined amount. This reduces the probability that the selected storage device is selected at a subsequent time. When the data extent is de-allocated, the weight associated with the affected storage device containing the now-de-allocated data extent is increased by a predetermined amount. This increases the probability that the storage device is selected at a subsequent time.

Abstract: A system, method, and computer program product for the banded allocation of storage device address ranges in distributed parity schemes is disclosed. A storage system with storage devices logically divides up the storage devices into bands of contiguous logical block address ranges. A storage controller provisions logical volumes in the bands. Upon unavailability of a storage device, the data pieces are reconstructed at the next available data extent within the same band on the other storage devices. The storage controller detects a replacement drive and logically divides the replacement storage device into the same number of bands as on the other storage devices. The storage controller transfers the reconstructed data pieces to the replacement drive and places the data pieces within the same bands on the replacement drive.

Abstract: Systems and techniques for performing a data transaction are disclosed that provide improved cache performance by pinning recovery information in a controller cache. In some embodiments, a data transaction is received by a storage controller of a storage system. The storage controller determines whether the data transaction is directed to a data stripe classified as frequently accessed. Data associated with the data transaction and recovery information associated with the data transaction are cached in a cache of the storage controller. The recovery information is pinned in the cache based on the data transaction being directed to the data stripe that is classified as frequently accessed, and the data is flushed from the cache independently from the pinned recovery information.

Abstract: A system, method, and computer program product for the banded allocation of storage device address ranges in distributed parity schemes is disclosed. A storage system with storage devices logically divides up the storage devices into bands of contiguous logical block address ranges. A storage controller provisions logical volumes in the bands. Upon unavailability of a storage device, the data pieces are reconstructed at the next available data extent within the same band on the other storage devices. The storage controller detects a replacement drive and logically divides the replacement storage device into the same number of bands as on the other storage devices. The storage controller transfers the reconstructed data pieces to the replacement drive and places the data pieces within the same bands on the replacement drive.

Abstract: A method, apparatus, and system of a priority command queues for low latency solid state drives are disclosed. In one embodiment, a system of a storage system includes a command sorter to determine a target storage device for at least one of a solid state drive (SSD) command and a hard disk drive (HDD) command and to place the command in a SSD ready queue if the SSD command is targeted to a SSD storage device of the storage system and to place the HDD command to a HDD ready queue if the HDD command is targeted to an HDD storage device of the storage system, a SSD ready queue to queue the SSD command targeted to the SSD storage device, and a HDD ready queue to queue the HDD command targeted to the HDD storage device.

Abstract: The present invention is a system and method which allows for a VTL system that supports thin provisioning to implicitly unmap unused storage. Such unmap operations may occur even though the VTL system does not receive any explicit unmap requests from its initiators. For example, if a system administrator knows that once a virtual tape drive of the VTL system has been partially overwritten, all previously written data sets on that virtual tape drive will never again be accessed, the system administrator may configure the VTL system so that it unmaps the entire remainder of the virtual tape drive on the first data overwrite.

Abstract: A method, apparatus, and system of a priority command queues for low latency solid state drives are disclosed. In one embodiment, a system of a storage system includes a command sorter to determine a target storage device for at least one of a solid state drive (SSD) command and a hard disk drive (HDD) command and to place the command in a SSD ready queue if the SSD command is targeted to a SSD storage device of the storage system and to place the HDD command to a HDD ready queue if the HDD command is targeted to an HDD storage device of the storage system, a SSD ready queue to queue the SSD command targeted to the SSD storage device, and a HDD ready queue to queue the HDD command targeted to the HDD storage device.

Abstract: The present invention is directed to a method for completing a stripe write operation in a timely fashion to a RAID drive pool which includes an abnormally slow drive. For example, the stripe write operation either completes within a required time interval, or an error is provided to the host/initiator which provides an indication to an application that the stripe write operation did not complete.

Abstract: Methods and systems for data reconstruction following drive failures may include: storing data across two or more drives in one or more data stripes, each data stripe including two or more drive extents; detecting a degradation of a drive containing a drive extent associated with a first data stripe; assigning a reconstruction priority to the drive extent associated with the first data stripe; detecting a degradation of a drive containing a drive extent associated with a second data stripe; and assigning a reconstruction priority to the drive extent associated with the second data stripe.

Abstract: A method for computing and storing parity information in a RAID system includes dividing each segment in a stripe into a data block and a parity block, and storing in each parity block, parity information for a limited number of other data blocks in the stripe. A method for rebuilding data in a RAID system includes rebuilding the data from parity information and storing the rebuilt data on reserve portions of the remaining disks in the system.

Abstract: The present invention is directed to a method for pre-emptive read reconstruction. In the method(s) disclosed herein, when a pre-emptive read reconstruction timer times out, if one or more drive read operations for providing requested stripe read data are still pending; and if stripe read data corresponding to the pending drive read operations may be constructed (ex.—reconstructed) based on the stripe read data received before the expiration of the timer, the pending drive read operations are classified as stale, but the pending drive read operations are still allowed to complete rather than being aborted, thereby promoting efficiency of the data storage system in situations when the data storage system includes an abnormal disk drive (ex.—a disk drive which endures random cycles of low read performance).

Abstract: The present invention is directed to a method for completing a stripe write operation in a timely fashion to a RAID drive pool which includes an abnormally slow drive. For example, the stripe write operation either completes within a required time interval, or an error is provided to the host/initiator which provides an indication to an application that the stripe write operation did not complete.

Abstract: A method for computing and storing parity information in a RAID system includes dividing each segment in a stripe into a data block and a parity block, and storing in each parity block, parity information for a limited number of other data blocks in the stripe. A method for rebuilding data in a RAID system includes rebuilding the data from parity information and storing the rebuilt data on reserve portions of the remaining disks in the system.

Abstract: The present disclosure is directed to a system and a method for optimizing redundancy restoration in distributed data layout environments. The system may include a plurality of storage devices configured for providing data storage. The system may include a prioritization module communicatively coupled to the plurality of storage devices. The prioritization module may be configured for determining a restoration order of at least a first data portion and a second data portion when a critical data failure occurs. The system may include a restoration module communicatively coupled to the plurality of storage devices and the prioritization module, the restoration module configured for restoring at least the first data portion and the second data portion based upon the restoration order.

Abstract: Methods and systems for data distribution may include, but are not limited to: receiving a request from a client device to store data on a distributed storage system; obtaining a hierarchical cluster map representing the distributed storage system; selecting an object at a hierarchical level of the cluster map; determining if the hierarchical level is a drive level; and adding a drive identifier associated with the object to a drive identifier array if the hierarchical level is the drive level.

Abstract: The present invention is a method for drive management and data placement in an archival storage system having a set of drives. The method includes mapping redundant data stripes onto the drives. A first active data stripe, located on a first subset of the drives, is then selected from the mapped data stripes. The first subset is placed into a normal power state and a second subset of the drives is placed into a low power state. Data is then written to the first active data stripe. Before the first active data stripe is fully used, the method includes selecting a next active/second active data stripe from the mapped data stripes, the second active data stripe being at least partially located on the second subset. The method may be performed by a system which implements MAID techniques for drive management and CRUSH for data placement.

Abstract: Methods and structure for online migration of data in a storage system comprising a plurality of storage devices. The method comprises redefining a volume of a storage system mapped according to a first mapping structure by defining a second mapping structure. The method further comprises quiescing processing of host I/O requests directed to the volume and transitioning control of the volume from a first to a second volume manager so as to utilize the benefits of the second mapping structure. The method further comprises commencing processing of host I/O requests directed to the volume wherein the volume is mapped according to the second mapping structure. The method further comprises migrating, via the second volume manager, volume data to any of a plurality of storage devices of the system, online, without interrupting processing of host I/O requests directed to the volume. This migrates volume data without significant downtime or wasted space.