Abstract: A method for managing read requests, the method may include receiving from a requesting entity a read request for reading an information unit stored in a storage system; determining by a control entity of the storage system whether the information unit is cached in a cache memory of the storage system and whether at least a predetermined number of disk drives of the storage system are currently overloaded; introducing a delay to a response to the read request thereby increasing a time difference between a time of the receiving of the read request and a time of a provision of the information unit to the requesting entity, if it is determined that the information unit is not cached in the cache memory and that the at least predetermined number of disk drives of the storage system are currently overloaded; and providing the information unit to the requesting entity.

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: A method and a storage system for managing logical objects, wherein the storage system includes a plurality of control servers and the method includes: (i) defining a plurality of object pools and associating each logical object, hosted in the storage system, with one of the plurality of object pools; (ii) configuring each control server to have a primary responsibility over at least two of the object pools, such that each object pool is controlled by one primary control server, configured to handle requests directed to logical objects associated with the object pool; and (iii) in response to a failure of one of the plurality of control servers, configuring each operational server of the plurality of control servers to take over primary responsibility for at least one object pool, originally defined under the primary responsibility of the failed control server.

Abstract: According to the teaching disclosed herein there is provided at least a method, system and device for managing a cache memory of a storage system. The storage system is associated with at least one physical storage device and, responsive to a read request, comprising information indicative of a logical address of at least one requested data unit, to obtain a storage physical address associated with the logical address, search the cache memory for a data unit associated with the storage physical address and service the request from the cache in case the data unit is found in the cache 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: A method for a snapshot family based reading of data units from a storage system, the method comprises: receiving a read request for reading a requested data entity, searching in a cache memory of the storage system for a matching cached data entity, if not finding the matching cached data entity then: searching for one or more relevant data entity candidates stored in the storage system; selecting, out of the one or more relevant data entity candidates, a selected relevant data entity that has a content that has a highest probability, out of contents of the one or more relevant data entity candidates, to be equal to the content of the requested data entity; and responding to the read request by sending the selected relevant data entity.

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: 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: A system for managing data includes providing at least one logical device having a table of information that maps sections of the logical device to sections of at least two storage areas. Characteristics of data associated with a one section of the logical device may be evaluated. The section of the data may moved between the at least two storage areas according to a policy and based on the characteristics of the data. The table of information is updated according to the movement of data between the at least two storage areas. Each of the at least two storage areas may correspond to a different storage tier, and each of the storage tiers may have different characteristic, such as speed of pools of storage devices within the tiers. A write target policy may be applied to store initial writes in a preferred location of the at least two storage areas.

Abstract: A method of operating a storage system includes: configuring the address space so that each LBA is assigned to at least two servers among a plurality of at least three servers in a control grid: to a primary server with a primary responsibility for handling requests corresponding to said LBA, and to a secondary server with a secondary responsibility for handling requests corresponding to said LBA. In response to a request corresponding to a certain LBA range, generating by a data server having primary responsibility over the certain LBA range, a primary cache object; identifying a data server configured as a secondary data server with regard to the certain LBA range; and generating a redundancy cache object corresponding to the primary cache object only at the identified secondary data server, the redundancy cache object to be used by the identified secondary data server when taking the primary responsibility.

Abstract: A storage system that may include a management module, a communication module and a storage module; wherein the management module is arranged to receive, at an intermediate point in time that occurs between the first point in time and a second point in time, a first request that indicates that a certain extent of the second logical volume is irrelevant; participate in a creation of second point in time snapshots of the first and second logical volumes; select, in response to the first request, out of all data deltas generated between the first and second point in time, selected data deltas to be transmitted to the other storage system; wherein the selected data deltas exclude data deltas associated with the certain extent that were generated between the first point in time and the intermediate point in time.

Abstract: There is provided a storage system comprising a control layer operable to manage a plurality of snapshot families, each family constituted by snapshot family members having hierarchical relations therebetween. The method of operating the storage system comprises searching a cache memory for an addressed data block corresponding to an addressed LBA and associated with an addressed snapshot family and an addressed SF member. In a case of missing the addressed data block in the cache memory, identifying in the cache memory all dirty data blocks corresponding to the addressed LBA and associated with the addressed snapshot family (candidate data blocks); identifying among SF members of the addressed snapshot family a destage owner, and in a case when the identified destage owner is associated with a candidate data block, reading from the cache memory such candidate data block.

Abstract: There is provided a storage system and a method of identifying delta-data therein between two points-in-time. The method comprises: generating successive snapshots Si and Si+1 corresponding to the two points-in-time; upon generating the snapshot Si+1, searching the cache memory for data blocks associated with snap_version=i, thereby yielding cached delta-metadata; searching the SF mapping data structure for destaged data blocks associated with snap_version=i, thereby yielding destaged delta-metadata; and joining the cached delta-metadata and the destaged delta-metadata, thereby yielding delta-metadata indicative of the delta-data between points-in-time corresponding to the successive snapshots with Snap_ID=i and Snap_ID=i+1. The method operates with no need in copying, destaging to a dedicated location and/or any other special handling of data that needs to be transmitted to the RS system.

Abstract: There is provided a storage system comprising a control layer operable to manage a snapshot family (SF) constituted by SF members having hierarchical relations represented by a SF relationship data structure and a method of operating thereof. Upon receiving a command for restoring a writable SF member from a read-only snapshot thereof, the control layer provides a foreground atomic operation. The atomic operation comprises generating a new writable snapshot of the read-only snapshot (a destination SF member), modifying the SF relationship data structure, and re-assigning all logical unit numbers (LUNs) from the writable SF member to be restored to the destination SF member. Upon successful completion of the atomic operation, the control layer sends acknowledgement indicative of successful restoring the writable SF member.

Abstract: There is provided a storage system capable to maintain a snapshot family comprising a plurality of members having hierarchical relations therebetween, and a method of operating thereof.

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: In accordance with certain aspects of the presently disclosed subject matter, there is provided a storage system and a method of storing data thereof. The method comprises: storing a plurality of snapshots of a certain source; assessing to at least one given snapshot an assessed value characterized by at least one of the following values and/or derivatives thereof: i. a first value characterizing the amount of unique physical data blocks associated, merely, with said given snapshot; ii. a second value characterizing the amount of unique physical blocks associated merely with a certain group of snapshots comprising said given snapshot; iii a combination of the first and the second value; and updating the assessed value responsive to a pre-defined event.

Abstract: The presently disclosed subject matter includes, inter alia, a storage system and a method of managing allocation of data in case an enclosure in a storage system becomes unavailable. The storage system has a storage space configured as a plurality of RAID groups, each RAID group comprising N parity members. According to one aspect of the disclosed subject matter, responsive to a write request, at least one section allocated to a disk in an unavailable enclosure is identified; at least one temporary RAID group in a spare storage space of the storage system is allocated and data related to the write request is written to the alternative RAID group.

Abstract: Described are techniques for processing a data operation in a data storage system. A front-end component of the data storage system receives the data operation. In response to receiving the data operation, the front-end component performs first processing. The first processing includes determining whether the data operation is a read operation requesting to read a data portion which results in a cache miss; and if said determining determines that the data operation is a read operation resulting in a cache miss, performing read miss processing. Read miss processing includes sequential stream recognition processing performed by the front-end component to determine whether the data portion is included in a sequential stream.

Abstract: There is provided a storage control grid capable of controlling at least one service provided in the storage system and a method of operating thereof. The storage control grid comprises at least one service dispatcher operatively coupled to at least one service requestor and to a plurality of service providers. The method comprises requesting by service requester a service, thus giving rise to at least one service request; enabling, using said at least one service dispatcher, delivery of the service request to at least one service provider among said plurality of service providers, said service provider configured to provide said at least one service, wherein the delivery is enabled in accordance with data comprised in a service data structure handled by said at least one service dispatcher and indicative, at least, of association between said at least one service and service providers among said plurality of service providers.