Abstract: There are provided a mass storage system and a method of operating thereof. The method comprises: a) dividing the storage space into a first portion configured to be available to a client and a second portion configured to be unavailable to a client, thus giving rise, respectively to an available storage space and a spare storage space; b) distributing the available space and the spare space over the disk drives thus giving rise to available space and spare space allocated to each given disk drive; c) detecting underperformance of at least one disk drive among the plurality of disk drives; d) responsive to detecting underperformance, decreasing respective available space allocated to said at least one underperforming disk drive and respectively increasing spare space allocated to said at least one underperforming disk drive thus giving rise to a re-configured allocation of the available space; and e) transferring the stored data in accordance with said re-configured allocation of the available space.

Abstract: The is provided a method of hot backward compatible upgrade of a storage system comprising a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space divided between a plurality of virtual partitions (VPs), and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of at least three data servers, each server having direct or indirect access to the entire address space.

Abstract: There is provided a storage system and method of operating thereof. The storage system comprises a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space divided between a plurality of virtual partitions (VP), and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of data servers, each server having direct or indirect access to the entire address space.

Abstract: The is provided a storage system comprising a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space, and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of data servers.

Abstract: There is provided a storage system comprising a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space, and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of data servers, each server comprising operatively coupled cache memory and non-volatile memory.

Abstract: There is provided a SAS grid storage system and a method of operating thereof. The system comprises a) a storage control grid comprising a plurality of interconnected data servers operable in accordance with at least one SAS protocol and b) a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space. Each disk unit comprises at least one input/output (IO) module comprising at least one internal SAS expander configured as a target with regard to the storage control grid. The plurality of disk units is operatively connected to the storage control grid in a manner enabling to each data server comprised in the storage control grid an access to each disk unit among the plurality of disk units.

Abstract: Handling a write operation to write data to a section of a storage device includes determining if the section needs to be copied to at least a first target device and, if the section of the storage device needs to be copied to the at least first target device, providing the data to a memory location and confirming completion of the write operation prior to copying the section of the storage device to the at least first target device. Handling a write operation to write data to a section of a storage device may also include determining if a slot in a cache memory corresponding to the section of the storage device needs to be copied to at least a second target device. If so, then in some cases the slot may be copied to the at least second target device prior to providing the data to the memory location.

Abstract: Described are techniques for selective data replication. Cached data is replicated if it is characterized as critical. Critical data may include data associated with a write I/O operation. Cache locations are selected for replicated data so that a first location is mapped to a first memory board and a second location is mapped to a second memory board. Data for a read operation is not replicated in cache. Other non-cache data that is critical and thus replicated includes metadata. Cache locations for data of read and write I/O operations are selected dynamically at the time the I/O operation is made from the same pool of cache locations.

Abstract: Accessing data memory includes writing data to a first memory location and to a second memory location in response to a request to write data to a memory address that corresponds to both locations, where the first and second memory locations are mirrored, in response to a request to read data from the memory address, reading data from the first memory location or the second memory location based on load balancing, and accessing data from the second memory location in response to a request to access data at the memory address when memory hardware corresponding to the first memory location has failed. Accessing the data memory may include requesting access to a specific one of the first and second memory locations. The memory address may contain a portion that is common to both the first memory location and the second memory location. Hardware coupled to the memory may cause data written using the memory address to be automatically written to the first memory location and the second memory location.

Abstract: Restoring data includes providing data in a first storage area of a first type that contains sections of data, providing data in a second storage area of a second type wherein the second type has, for each section of data thereof, either a pointer to a corresponding section of data of the first storage area or a pointer to corresponding section of data of a third storage area of the first type, providing data in at least one other storage area of the second type, and, for each particular section of data of the second storage area having a pointer to the third storage area, providing to a corresponding section of the first storage area an indirect pointer to a corresponding section of the third storage area if no storage areas of the at least one other storage area point to the corresponding section of the first storage area.

Abstract: A method for copying data from a source logical device to a destination logical device. In response to a copy command from a requesting host application identifying the source and destination logical devices, an environment is established. Thereafter a calling system receives an immediate response that the copy operation is complete even though no data has been copied. Application programs may access storage locations in either the source or the destination logical device during the copy phase. A copy program transfers the date on a track-by-track basis to the destination logical device. Procedures assure that any data access to a particular track in either the source or destination logical device by any application prior to the transfer of that track is accommodated to maintain data integrity.

Abstract: Ordering data writes include a host computer providing a plurality of data writes to a primary storage device, the primary storage device assigning a first sequence number to data writes begun after a first time and before a second time, the primary storage device assigning a second sequence number, different from the first sequence number, to data writes begun after the second time, in response to completion of all writes assigned the first sequence number, the primary storage device transferring writes assigned the first sequence number to a secondary storage device, and, in response to the primary storage device transferring all writes assigned the first sequence number to the secondary storage device, the primary storage device sending a commit message to the secondary storage device. Ordering data writes may also include, in response to receiving a commit message from the primary storage device, the secondary storage device storing the data writes having the first sequence number.

Abstract: Using a local storage device to read desired data stored on a remote storage device that receives chunks of data from the local storage device includes, if the desired data is entirely in a cache of the local storage device, the local storage device returning the data from the cache and, if the desired data is not entirely in a cache of the local storage device, reading data from the remote storage device to the local storage device and the local storage device merging the data from the remote storage device with data from the local storage device at the local storage device. Using a local storage device to read desired data stored on a remote storage device that receives chunks of data from the local storage device may also include, prior to reading data from the remote storage device to the local storage device, creating a temporary storage area at the local storage device if there is data from the local storage device that is to be read. The temporary storage area may be a scratch slot.

Abstract: Accessing stored data includes providing a virtual storage area having a table of pointers that point to one of: a disk storage area and a volatile memory area, wherein the virtual storage area contains no sections of data, in response to a request for accessing data of the virtual storage area, determining whether a corresponding one of the pointers points to the disk storage area or points to the volatile storage area and accessing the data from the disk storage area or from the volatile storage area. Accessing stored data may also include associating a first one of the other storage areas with the virtual storage area, wherein the virtual storage area represents a copy of data of the disk storage area. Accessing stored data may also include causing all of the pointers of the table to initially point to sections of the disk storage area when the virtual storage area is initially associated with the disk storage area.

Abstract: Accessing stored data includes providing a virtual storage area having a table of pointers that point to sections of at least two other storage areas, where the virtual storage area contains no sections of data, in response to a request for accessing data of the virtual storage area, determining which particular one of the other storage areas contain the data, and accessing the data on the particular one of the other storage areas using the table of pointers. Accessing stored data may also include associating a first one of the other storage areas with the virtual storage area, where the virtual area device represents a copy of data of the first one of the other storage areas. Accessing stored data may also include causing all of the pointers of the table to initially point to sections of the first one of the other storage areas when the virtual storage area is initially associated with the first one of the other storage areas. The storage areas may be storage devices. The sections may be tracks.

Abstract: Handling data includes providing a first storage area of a first type that contains sections of data, providing a second storage area of the first type that contains sections of data, providing a third storage area of a second type where the second type has, for each section thereof, a pointer to one of: a corresponding section of data of the first storage area and a corresponding section of data of the second storage area, causing the third storage area to be not available for accessing, and after causing the third storage area to not be available for accessing, providing data from the second storage area corresponding to pointers of the third storage area that point to sections of the second storage area.

Abstract: Accessing stored data includes providing a virtual storage area having a table of pointers that point to sections of at least two other storage areas, where the virtual storage area contains no sections of data, in response to a request for accessing data of the virtual storage area, determining which particular one of the other storage areas contain the data, and accessing the data on the particular one of the other storage areas using the table of pointers. Accessing stored data may also include associating a first one of the other storage areas with the virtual storage area, where the virtual area device represents a copy of data of the first one of the other storage areas. Accessing stored data may also include causing all of the pointers of the table to initially point to sections of the first one of the other storage areas when the virtual storage area is initially associated with the first one of the other storage areas. The storage areas may be storage devices. The sections may be tracks.

Abstract: A method and apparatus for data recovery in a system involving a first data store acting as a standard device and a physical moving mirror data store that operates as moving mirror with a first mode to be synchronized and in a second, isolated mode. In response to a command to establish a third or protected restore operating mode, the data to be transferred in response to that command is identified. A restoration procedure copies data from the second data store to the first store to recover any data that may have been corrupted in the second data store. An update procedure acts on the restored data concurrently with the restoration procedure.

Abstract: Handling a faulting memory of a pair of mirrored memories includes initially causing a non-faulting memory of the pair of mirrored memories to service all read and write operations for the pair of mirrored memories, determining that hardware corresponding to the faulting memory of the pair of mirrored memories has been successfully replaced to provide a new memory, in response to the new memory being provided, causing data to be copied from the non-faulting memory to the new memory while data is being read to and written from the non-faulting memory, and, in response to successful copying to the new memory, causing writes to be performed to both memories of the pair of mirrored memories and selecting one of the pair of mirrored memories for read operations when one or more read operations are performed.

Abstract: Restoring data includes providing data in a first storage area that contains sections of data, providing data in a second storage area where the second type has, for each section of data thereof, at least one of: a pointer to a corresponding section of data of the first storage area and a pointer to corresponding section of data of a third storage area of the first type. In one embodiment, a sections of the first storage area are replaced with pointers to the third storage area. In other embodiments, sections of a fourth storage area of the first type are replaced with pointers to the third storage area and optionally with pointers to the first storage area. In another embodiment, data is copied from the second storage area to a third storage area of the second type.