Abstract: A method for controlling compression based on compression ratio, the method includes monitoring access requests related to a storage entity of a storage system; wherein the access requests are associated with multiple data units; evaluating a compression ratio related to the storage entity; wherein the evaluating comprises applying a first compression process on at least a subset of the multiple data units to provide first compressed data units; serving the access requests without storing, in a permanent storage layer of the storage system, the first compressed data units; and reacting, by the storage system, to the compression ratio.

Abstract: A method for memory management, the method may include receiving an updated portion of a data unit, the data unit is associated with a logical data entity; wherein the updated portion is smaller than a granularity of a mapping data structure used for retrieval of the data unit; and creating, by the storage system an extended data unit that comprises (i) an original content of the data unit, (ii) the updated portion and, (iii) updated portion metadata; wherein the updated portion metadata comprises (a) updated portion retrieval information for retrieving the updated portion, and (b) updated portion snapshot information indicative of at least one snapshot associated with the updated portion.

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: 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 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: A method for managing physical resources of a storage system, the method may include transmitting, to a remote site, first information representative of a first snapshot of a logical entity; wherein the first snapshot is associated with first data that is stored in first physical addresses of the storage system; wherein the first physical addresses are mapped to first logical addresses; receiving from the remote site a first acknowledgment indicating that the first information was fully received by the remote site; and disassociating, in response to a reception of the first acknowledgement, the first snapshot from the first physical addresses while maintaining a logical association between the first snapshot and the first logical addresses.

Abstract: A method for memory management, the method may include receiving an updated portion of a data unit, the data unit is associated with a logical data entity; wherein the updated portion is smaller than a granularity of a mapping data structure used for retrieval of the data unit; and creating, by the storage system an extended data unit that comprises (i) an original content of the data unit, (ii) the updated portion and, (iii) updated portion metadata; wherein the updated portion metadata comprises (a) updated portion retrieval information for retrieving the updated portion, and (b) updated portion snapshot information indicative of at least one snapshot associated with the updated portion.

Abstract: A method that includes calculating multiple set parity units for multiple sets of data units that are cached in a storage system thereby providing a group of units that includes multiple sets of units. Each set of units includes a set of data units and at least one associated set parity unit that facilitate a reconstruction of the set of units when a first number of units of the set of units is lost. Calculating at least one group parity unit for the group of units. A combination of the at least one group parity unit and at least one associated set parity unit facilitate a reconstruction of the set of units upon a failure of a second number of units of the set of units. The second number of units of the set of units exceeds the first number of units of the set of units. Destaging the group of units and the at least one group parity unit to multiple disks of the storage system.

Abstract: There is provided a storage system and a method of moving a source data portion from a source logical volume to a destination logical volume. The method comprises: configuring a source mapping data structure to comprise an entry indicative of mapping between logical addresses corresponding to source data portion and addresses corresponding to source data portion and related to a physical address space; and, responsive to a move command, providing an atomic operation comprising configuring a destination mapping data structure to comprise an entry associated with said at least one destination range and comprising a reference to said entry in the source mapping data structure; and configuring said at least one entry in the source mapping data structure DSsrc to bear an indication that said one or more contiguous ranges of addresses corresponding to said source data portion in the source logical volume Vsrc are unavailable to a client.

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 method that may include calculating multiple set parity units for multiple sets of data units that are cached in a storage system thereby providing multiple sets of units. Each set of units includes a set of data units and at least one associated set parity unit that facilitate a reconstruction of the set of units when a first number of units of the set of units is lost. Calculating at least one group parity unit for the group of units. A combination of the at least one group parity unit and at least one associated set parity unit facilitate a reconstruction of the set of units upon a failure of a second number of units of the set of units. The second number exceeds the first number. Destaging the group of units and the at least one group parity unit to multiple disks of the storage system.

Abstract: A method for responding to an extent change operation, the method may include receiving, by a storage system and from a requesting entity, a request to perform an extent content change operation that involves changing a content of a certain extent within a logical space supported by a storage system; generating, in response to the request, extent change operation information that comprises (a) an event counter indicative of a time of requested occurrence of the extent change operation, (ii) a type of extent change operation indicator, and (ii) logical addresses associated with the extent change operation; and sending to the requesting entity an acknowledgement indicative of a completion of the extent change operation before a completion of the extent change operation if an expected content of the certain extent is known before completion of the extent change operation.

Abstract: A method for managing physical resources of a storage system, the method may include transmitting, to a remote site, first information representative of a first snapshot of a logical entity; wherein the first snapshot is associated with first data that is stored in first physical addresses of the storage system; wherein the first physical addresses are mapped to first logical addresses; receiving from the remote site a first acknowledgment indicating that the first information was fully received by the remote site; and disassociating, in response to a reception of the first acknowledgement, the first snapshot from the first physical addresses while maintaining a logical association between the first snapshot and the first logical addresses.

Abstract: A method for responding to an extent change operation, the method may include receiving, by a storage system and from a requesting entity, a request to perform an extent content change operation that involves changing a content of a certain extent within a logical space supported by a storage system; generating, in response to the request, extent change operation information that comprises (a) an event counter indicative of a time of requested occurrence of the extent change operation, (ii) a type of extent change operation indicator, and (ii) logical addresses associated with the extent change operation; and sending to the requesting entity an acknowledgement indicative of a completion of the extent change operation before a completion of the extent change operation if an expected content of the certain extent is known before completion of the extent change operation.

Abstract: A storage system and a method for managing a memory capable of storing metadata related to logical volume sets, are disclosed. A memory quota is assigned to a metadata related to a logical volume set. The size of a memory currently consumed by the metadata is monitored. Upon exceeding a threshold by the size of the monitored memory, at least one restraining action related to memory consumption by the metadata is applied.

Abstract: There is provided a storage system and a method of migrating a source data portion from a source logical volume to a destination range in a destination logical volume. The method comprises: configuring a source mapping data structure to comprise an entry associated with said source data portion and indicative of mapping between logical addresses corresponding to said source data portion and addresses corresponding to said source data portion and related to a physical address space; and, responsive to a migration command, configuring a destination mapping data structure to comprise an entry associated with said at least one destination range and comprising a reference to said entry in the source mapping data structure, said entry in the source mapping data structure to be used for mapping to said addresses related to said physical address space and corresponding to the source data portion and to the migrated data portion.

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: 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.