Abstract: A method of migrating data from a source storage resource to a destination storage resource involves selecting a source volume in the source storage resource; configuring in the destination storage resource a destination volume corresponding to the source volume and having the same properties; and redirecting I/O requests from an application running on a host to the destination volume instead of the source volume, whilst migrating data stored in the source volume to the destination volume. A storage system is operable as a destination storage system for migrating data from a source storage system, including means for configuring a destination volume corresponding to a source volume in the source storage system and a migration module having a non-transitory computer useable medium and operable to initiate read requests addressed to the source volume thereby enabling a background process of migrating data stored in the source volume to the destination volume.

Abstract: A mass storage system and method incorporates a cache memory or a cache management module which handles dirty data using an access-based promotion replacement process through consistency checkpoints. The consistency checkpoints are associated with a global number of snapshots generated in the storage system. The consistency checkpoints are organized within the sequence of dirty data in an invariable order corresponding to storage volumes with the generated snapshots, such that, responsive to destaging a consistency checkpoint the global number of generated snapshots are recorded and then read during recovery of the failed storage system.

Abstract: A method and system are disclosed for storage optimization. Data parts and metadata within a source data unit are identified and the data parts are compared with data which is already stored in the physical storage space. In case identical data parts are found within the physical storage, the data parts from the source data unit are linked to the identified data, while the data parts can be discarded, thereby reducing the required storage capacity. The metadata parts can be separately stored in a designated storage area.

Abstract: There are provided a mass storage system comprising a control layer operatively coupled to a physical storage space and operable to interface with one or more clients and to present to said clients a plurality of logical volumes. The method of operating the storage system comprises: dividing one or more logical volumes into a plurality of statistical segments with predefined size; assigning to each given statistical segment a corresponding activity level characterizing statistics of I/O activity with regard to data portions within the given statistical segment, said statistics collected over a plurality of cycles of fixed counting length; and managing one or more data storage processes in the storage system (e.g. a background defragmentation process, a background garbage collection process, a destage management process, etc.) using said activity level.

Abstract: There is provided a mass storage system and a method of operating thereof. The method comprises: a) generating one or more consistency checkpoints; b) associating each generated consistency checkpoint with a global number of snapshots generated in the storage system corresponding to time of generation of respective checkpoint; c) upon generating, placing each consistency checkpoint at the beginning of a sequence of dirty data portions which are handled in a cache memory with the help of a replacement technique with an access-based promotion; d) enabling within the sequence of dirty data portions an invariable order of consistency checkpoints and dirty data portions corresponding to volumes with generated snapshots; and e) responsive to destaging a certain consistency checkpoint, recording associated with the certain checkpoint global number of generated snapshots to a predefined storage location configured to be read during a recovery of the storage system.

Abstract: A storage system and method is provided including physical storage devices controlled by storage control devices constituting a storage control layer operatively coupled to the physical storage devices and hosts. The storage control layer includes a first virtual layer interfacing with the hosts, operable to represent a logical address space available to said hosts and characterized by an Internal Virtual Address Space (IVAS); a second virtual layer characterized by a Physical Virtual Address Space (PVAS), interfacing with the physical storage devices, and operable to represent an available storage space; and an allocation module operatively coupled to the first and second virtual layers and providing mapping between IVAP and PVAS. Each address in PVAS is configured to have a corresponding address in IVAS. The allocation module facilitates management of IVAS and PVAS, enabling separation of a process of deleting certain logical object into processes performing changes in IVAS and PVAS, respectively.

Abstract: A storage system and method is provided including physical storage devices controlled by storage control devices constituting a storage control layer operatively coupled to the physical storage devices and hosts. The storage control layer includes: a first virtual layer interfacing with the hosts, operable to represent a logical address space characterized by logical block addresses and available to said hosts and characterized by an Internal Virtual Address Space (IVAS) and operable, responsive to a configuration or I/O request addressed to the logical block addresses, to translate said logical block addresses into IVAS addresses; and a second virtual layer interfacing with the physical storage devices, operable to represent an available physical space to said hosts and characterized by a Physical Virtual Address Space (PVAS), addresses in PVAS having corresponding address in IVAS. The second virtual layer is operable to translate said respective IVAS addresses into addresses in the physical address space.

Abstract: A storage system and method are provided including physical storage devices controlled by storage control devices constituting a storage control layer operatively coupled to the physical storage devices and hosts. The storage control layer includes: a first virtual layer interfacing with the hosts, operable to represent a logical address space characterized by logical block addresses, characterized by an Internal Virtual Address Space (IVAS) and operable, responsive to I/O requests addressed to logical block addresses, to provide protocol-dependent translation of said logical block addresses into IVAS addresses; and a second virtual layer interfacing with the physical storage space, and operable to represent available physical space to said hosts and characterized by a Physical Virtual Address Space (PVAS). Each address in PVAS having a corresponding address in IVAS.

Abstract: A control layer of a data storage system is configured to identify one or more physical data units in the physical storage, which are associated only with corresponding logical snapshot data units, and to reallocate such physical snapshot data units to a dedicated storage space. The dedicated storage space can be a low-power storage space, which includes one or more disks designated as low power disks. The reallocation of snapshot data units to low power disks can be carried out according to an energy-aware migration policy, directed for minimizing the activation of the low power disks, and maintaining the disks in an inactive state for longer periods of time.

Abstract: There are provided a storage system with reduced energy consumption and a method of operating thereof. The method comprises caching in the cache memory a plurality of data portions corresponding to one or more incoming write requests, to yield cached data portions; consolidating the cached data portions characterized by a given level of expected I/O activity addressed thereto into a consolidated write request; and, responsive to a destage event, enabling writing the consolidated write request to one or more disk drives dedicated to accommodate data portions characterized by said given level of expected I/O activity addressed thereto. The cached data portions consolidated into the consolidated write request can be characterized by expected low frequency of I/O activity, and the respective one or more dedicated disk drives can be configured to operate in low-powered state unless activated.

Abstract: There are provided a mass storage system and a method of operating thereof. The method comprises: dividing one or more logical volumes into a plurality of statistical segments with predefined size; assigning to each given statistical segment a corresponding activity vector characterizing statistics of I/O activity with regard to data portions within the given statistical segment, said statistics collected over a plurality of cycles of fixed counted length; and evaluating similarity of expected I/O activity with regard to certain data portions with the help of activity vectors. Two data portions are characterized by similar expected I/O activity if a distance between activity vectors characterizing respective statistical segments matches a similarity criterion.

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 are provides an allocation module and a method of allocating a logical disk to a next member of a given RAID group. The method comprises: identifying one or more physical disks comprising at least one logical disk with already allocated member of said given RAID group, thus giving rise to allocated physical disks; identifying one or more pairs constituted by at least one allocated physical disk with non-allocated physical disks, said pairs having minimal number of RAID groups with members allocated to both physical disks in the pair, thus giving rise to a first group of pairs with minimal contention value; and selecting among the first group of pairs with minimal contention value one or more non-allocated physical disks as candidate physical disks for allocating said next member MEMi+1 of said given RAID group, wherein 0<i<N+1.

Abstract: There are provided a storage system and a method of operating thereof. The method comprises: caching in the cache memory a plurality of data portions matching a certain criterion, thereby giving rise to the cached data portions; analyzing the succession of logical addresses characterizing the cached data portions; if the cached data portions cannot constitute a group of N contiguous data portions, where N is the number of RG members, generating a virtual stripe being a concatenation of N data portions wherein at least one data portion among said data portions is non-contiguous with respect to any other portion in the virtual stripe, and wherein the size of the virtual stripe is equal to the size of the stripe of the RAID group; destaging the virtual stripe and writing it to a respective storage device in a write-out-of-place manner. The virtual stripe can be generated responsive to receiving a write request from a client and/or responsive to receiving a write instruction from a background process.

Abstract: Methods and systems are disclosed that relate to selecting a path for sending an I/O request from a host to a data storage subsystem from among a plurality of paths from the host to the subsystem. An exemplary method includes identifying a limitation on the traffic level for the plurality of paths, tracking a first metric corresponding to the limitation on the traffic level for each path, and transmitting a first I/O request having an urgency level other than the highest urgency level by one of the plurality of paths whose first metric does not exceed its limitation on the traffic level.

Abstract: There are provided a storage system and a method of operating thereof. The method comprises: a) representing to a plurality of hosts an available logical address space divided into one or more logical groups (e.g. logical volumes, virtual partitions, snapshots, combinations of a given logical volume and its respective snapshot(s), etc.), and b) mapping between one or more contiguous ranges of addresses related to the logical address space and one or more contiguous ranges of addresses related to the physical address space, wherein said mapping is provided with the help of one or more mapping trees, each tree assigned to a separate logical group in the logical address space.

Abstract: A data storage system having a packet switching network, a cache memory, and a plurality of directors, one portion of such directors being adapted for coupling to a host computer/server and another portion of the directors being adapted for coupling to a bank of disk drives. The plurality of directors and cache memory are interconnected through the packet switching network. Each one of the directors is adapted to transmit different types of information packets to another one of the directors through the network. Each one of the directors is adapted to transmit and receive different types of information packets to another one of the directors or cache memories through the packet switching network. Each one of the cache memories is adapted to receive and transmit different types of information packets to one of the directors through the packet switching network. One type of information packet requires a different degree of latency than another type of information packet.

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.