Abstract: A method for operating a data storage system that includes a plurality of mass storage devices, which are configured to store data redundantly, the method including determining a characteristic service level of one or more of the mass storage devices and defining a reduced service level, which is less than the characteristic service level. The method further includes performing the following steps automatically: detecting the reduced service level on a first mass storage device in the data storage system; determining that data on the first mass storage device is stored redundantly on a second mass storage device in the data storage system; and in response to detecting the reduced service level, diverting an input/output (IO) request for the data directed to the first mass storage device to the second mass storage device, while operating the first mass storage device at the reduced service level.

Abstract: A method for managing a data storage system, consisting of configuring a first cache to retrieve data from and store data at a first range of logical addresses (LAs) in a storage device. A second cache is configured to operate like the first cache. The method further includes configuring one or more third caches to retrieve data from and store data at a second range of LAs in the storage device. The method includes detecting an inability of the second cache to retrieve data from or store data at the first range of LAs. In response to the inability, at least one of the first cache and the one or more third caches are reconfigured to retrieve data from and store at the first range of LAs while continuing to retrieve data from and store at the second range of LAs.

Abstract: In accordance with some embodiments of the present invention, there is provided a cache management module for managing a cache memory device, comprising a groups management module adapted to define groups of allocation units in accordance with at least an operative criterion and to create a new group of allocation units whenever it is determined that in accordance with at least the operative criterion none of the one or more existing groups is appropriate to include an allocation unit, and a replacement procedure module adapted to manage the cache in terms of groups of allocation units, rather than in terms of discrete allocation units.

Abstract: Disclosed is a system and method from mirroring data from a data storage server/system. A mirroring module on a primary mirror server/system may forward one or more data packets received from the data storage server/system to a secondary mirror server/system. The one or more packets maybe received over a synchronous data link and forwarded over an asynchronous data link.

Abstract: Disclosed is a system, method and circuit for mirroring data on a data server. According to some embodiments of the present invention, a primary mirroring module associated with a primary server may be adapted to establish data mirroring connections between the primary server and one or more mirror sever systems. According to some embodiments of the present invention, the primary mirroring module includes an evaluator unit which generates a delta file to be transmitted to the one or more mirror server systems.

Abstract: A method for storing data, consisting of distributing a first plurality of groups of logical addresses among one or more storage devices in a storage system, receiving a second plurality of data-sets containing the data to be stored, and assigning each data-set among the plurality of data-sets a random number chosen from a first plurality of different numbers. The method further consists of partitioning each data-set into multiple partitions, so that each partition among the multiple partitions receives a sequential partition number, assigning each partition within each data-set to be stored at a specific group of logical addresses in the storage system in accordance with the sequential partition number of the partition and the random number assigned to the data-set, and storing each partition in the storage system at the assigned specific group of logical addresses.

Abstract: A method for maintaining integrity of data in a redundant mass storage system is provided that includes selecting a plurality of scrubbing selections for a memory system in which each of the scrubbing selections selects a data section on the memory system. The method also includes selecting a respective scrubbing implementation for each scrubbing selection in which each of the scrubbing implementations determines a data check. Another exemplary method is provided for ensuring integrity of data stored in a redundant mass storage system. An apparatus is provided for maintaining data integrity in a redundant mass storage system. A computer-readable storage medium containing a set of instructions for a general purpose computer is provided. The set of instructions include a method for ensuring data integrity in a redundant mass storage system.

Abstract: Disclosed is system and method for mirroring data from a primary data storage system on a mirroring data storage system. According to some embodiments to the present invention, prior to resynchronization of a data unit on the mirroring system with corresponding data on a primary unit, a consistent snap-shot of the data unit to be resynchronized is taken. According to some embodiments of the present invention, the snap-shop may be discarded upon completion of resynchronization.

Abstract: A method for continuous data protection in a storage system, including receiving a first write command to write first data to a partition of a logical volume and then generating a first partition descriptor record (PDR) having a first timestamp. The method further includes storing the first data at a first location, associating the first PDR with the first location, and receiving a second write command, subsequent to the first command, to update the first data with second data. Responsively to the second command, a second PDR having a second timestamp is generated. The second data is stored at a second location, and the second PDR is associated with the second location. The method includes generating a pointer between the first PDR and the second PDR, and accessing the first PDR using the pointer in response to a read command indicating a time prior to the second timestamp.

Abstract: A system and method are described to improve the efficiency of copy-on-write operations in a storage system. A partition mapping table is maintained in a cache memory, where the partition mapping table is used to translate logical partitions into physical partitions. A request is received to write one or more blocks BB to a partition PSS, and, upon receiving the request, the pointers in the partition mapping table are interchanged such that data associated with PSS is now associated with a second partition PTT. Next, block(s) BB is written to PSS and an indication is made on the PDSS descriptor that all other data blocks in the partition PSS are invalid.

Abstract: A method for managing a storage system, including storing first and second sets of data on a storage device in the system. The method further includes assigning a first restore preference level to the first set and a second restore preference level to the second set, such that applying the first level and the second level respectively to the first and second sets rebuilds the first set before the second set irrespective of physical locations and logical addresses of the sets on the storage device. The method also includes receiving an indication of a failure in the storage device, generating a command to rebuild the first set as a first restored set and the second set as a second restored set, and in response to the command, rebuilding the first set of the data and the second set of the data according to the respective restore preference levels.

Abstract: A method for managing activity of a data storage system, including at least partly managing and performing an operator interaction with the storage system using a first processing system, and monitoring operation of the first processing system using a second processing system. The method further includes detecting a failure in operation of the first processing system using the second processing system and at least partly managing and performing the operator interaction using the second processing system in response to detecting the failure.

Abstract: A method for distributing data over a set of N storage devices. The method includes apportioning the data into groups of (N?2) or fewer blocks, and adding to each group a parity block so as to form a parity set. The method further includes distributing the blocks of each parity set to the N storage devices so that each of the blocks is stored on a different storage device.

Abstract: A system and method are described to improve the efficiency of copy-on-write operations in a storage system. A partition mapping table is maintained in a cache memory, where the partition mapping table is used to translate logical partitions into physical partitions. A request is received to write one or more blocks BB to partition PSS, and, upon receiving the request, the pointers in the partition mapping table are interchanged such that data associated with PSS is now associated with PTT. Next, block(s) BB is written to PSS and a read command is issued so that data now associated to PTT is read into the memory and is associated with PSS, except for block(s) BB that was written. In an alternative scenario, the steps of writing block(s) BB to PSS and issuing a read command are performed simultaneously.

Abstract: A method for copying a logical volume in a data storage system, including forming a first logical volume having one or more logical partitions and storing data at a physical location associated with the one or more logical partitions. The method further includes receiving a first command to copy the first logical volume to a second logical volume, and responsively to the first command, assigning the one or more logical partitions to a meta-volume and linking the meta-volume to the first and second logical volumes. The method also includes receiving a second command to access the data in at least one of the first and second logical volumes, responsively to the second command, using a partition descriptor record associated with the meta-volume to identify the physical location, and providing access to the data at the physical location.

Abstract: A system and method are described to improve the efficiency of copy-on-write operations in a storage system. A PDSS descriptor associated with partition PSS and a PDTT descriptor associated with partition PTT are maintained in a cache memory, with partition PSS associated with a source logical unit LUS and partition PTT associated with a source logical unit LUT. An ICP flag is set in the PDSS and PDTT descriptors indicating that the PSS and PTT are undergoing a copy-on-write operation. Data is then dissociated with PTT and locations of each block of the PSS stored in memory are copied from the PDSS descriptor to the PDTT descriptor. A task is then created to fetch blocks of the PSS and the fetched blocks are copied from the PSS to the PTT.

Abstract: A method for copying a logical volume in a data storage system includes forming a first logical volume, storing in physical storage of the data storage system a quantity of data of the first logical volume, and receiving a first command to copy the first logical volume to a second logical volume. In response to the first command, meta-data is formed having a size that is independent of the quantity of the data. In response to a second command to access the data, the meta-data is used to access the data.

Abstract: In accordance with further embodiments of the present invention, there is provided a disk controller for managing the delegation of tasks from a disk controller to a disk, including a task delegation module adapted to delegate fetch or destage tasks to the disk in accordance with a relation between an amount of dirty data currently in a cache and a number of pending destage tasks currently being handled by the disk.

Abstract: Some embodiments of the present invention relate to a method and a circuit for managing the prefetching of data into a cache. According to some embodiments of the present invention a prefects controller may be adapted to trigger a prefetch operation for prefetching one or more data segments into the cache together with at least one segment to be fetched, and may be further adapted to establish a number of data segments to be prefetched together with the at least one segment to be fetched. According to some embodiments of the present invention, the prefetch controller may be adapted to establish what number of segments are to be prefetched at least in accordance with the number of successive segments, including one, already in the cache, which are spaced apart by no more than a predetermined number of segments relative to the at least one segment to be fetched.

Abstract: A method for managing multiple logical volumes in a data storage system, including providing physical storage of a given capacity within the data storage system, and adding a logical volume of a given size within the data storage system so as to cause a total amount of logical storage of the logical volumes in the data storage system to be greater than the given capacity of the physical storage. The method includes verifying, in response to a write command to store data in the logical volume, that a physical storage location is available in the physical storage and, if the physical storage location is available, then storing the data at the physical storage location.