Abstract: In order to avoid loss of data, computer systems are often connected to a UPS which provides power backup in case of an emergency shutdown resulting from a power failure. However, as UPS units are costly, they take up a lot of physical space and can provide power for a limited period of time, it would be advantageous to improve the efficiency of UPS devices and enable to utilize as much as possible of the UPS power in order to save data to a permanent storage before shutdown. There is provided a method and system for controlling the frequency of one or more processors in computer systems, responsive to an indication of a power failure, and thereby reduce its power consumption, so as to provide more power for writing write-pending data to a non-volatile data storage.

Abstract: The presently disclosed subject relates at least to a method and system for controlling access to a logical unit (LU) in a logical storage space, available to a given initiator, representing a corresponding physical storage space, said logical storage space being accessible via a storage control layer, said storage control layer being associated with a security manager. A first value is generated by the security manager, based on a secret key, and transmitted to host requesting permission to access the logical storage space, while the secret key is made available to a target associated with the logical storage space. The host sends to the control device an access related request, the request comprising a second value which was generated based on the first value. Responsive to the command the target calculates the first value, based on the secret key and the second value based on the first value.

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: Storage systems with reduced energy consumption, methods of operating thereof, corresponding computer program products and corresponding program storage devices. Some non-limiting examples of a write method include: configuring a plurality of storage disk units such that at any given point in time there are at least two storage disk drives operating in active state in any storage disk unit; caching in a cache memory one or more write requests and generating a consolidated write request corresponding to a stripe in a RAID group; destaging the consolidated write request; and writing the destaged consolidated write request in a write out of place manner to one or more storage disk drives operating at the destage point of time in active state.

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 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 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 provided a storage system, storage control unit and method of operating thereof. A storage system comprises a permanent storage subsystem comprising a first cache memory and a non-volatile storage medium, and a storage control unit operatively coupled to said subsystem and to a second cache memory operable to cache “dirty” data pending to be written to the permanent storage subsystem and to enable, responsive to at least one command by the control storage unit, destaging said “dirty” data or part thereof to the permanent storage subsystem.

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: 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.