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 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 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 providing a warranted snapshot that may include: receiving a request to create a first warranted snapshot of a first logical volume at a first point in time and creating the first warranted snapshot if the first warranted snapshot is non-writable and if an amount of physical storage actually devoted by a storage system to the first logical volume at the first point of time does not exceed a size of a free physical storage space that is available for storing any future data delta associated with the first warranted snapshot. The creating of the first warranted snapshot may include allocating a first virtual portion of a physical storage space for storing any future data delta associated with the first warranted snapshot. A size of the first virtual portion equals the amount of physical storage actually devoted to the first logical volume at the first point of time.

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 for providing a warranted snapshot that may include: receiving a request to create a first warranted snapshot of a first logical volume at a first point in time and creating the first warranted snapshot if the first warranted snapshot is non-writable and if an amount of physical storage actually devoted by a storage system to the first logical volume at the first point of time does not exceed a size of a free physical storage space that is available for storing any future data delta associated with the first warranted snapshot. The creating of the first warranted snapshot may include allocating a first virtual portion of a physical storage space for storing any future data delta associated with the first warranted snapshot. A size of the first virtual portion equals the amount of physical storage actually devoted to the first logical volume at the first point of time.

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 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 capable to maintain a snapshot family comprising a plurality of members having hierarchical relations therebetween, and a method of operating thereof.

Abstract: Described are techniques and criteria used in connection with cache management. The cache may be organized as a plurality of memory banks in which each memory bank includes a plurality of slots. Each memory bank has an associated control slot that includes groups of extents of tags. Each cache slot has a corresponding tag that includes a bit value indicating the availability of the associated cache slot, and a time stamp indicating the last time the data in the slot was used. The cache may be shared by multiple processors. Exclusive access of the cache slots is implemented using an atomic compare and swap instruction. The time stamp of slots in the cache may be adjusted to indicate ages of slots affecting the amount of time a particular portion of data remains in the cache. Each director may obtain a cache slot from a private stack of nondata cache slots in addition to accessing a shared cache used by all directors.

Abstract: Described are techniques for detecting incompatibilities. A first contents of a data item is determined in accordance with a first set of conventions associated with a first processor architecture. A second contents of said data item is determined in accordance with a second set of conventions associated with a second processor architecture and including at least one convention that is not included in said first set. An actual difference between the first contents and the second contents is determined. It is determined whether the actual difference is expected. If the actual difference is not expected, the data item is flagged as an incompatibility candidate. Code referencing the data item is examined to determine any coding incompatibilities due to coding dependencies.

Abstract: Described are techniques for determining a cache slot. A set of criteria for each of a plurality of families is received. A received data operation associated with a first of said plurality of families is obtained. It is determined, in accordance with the criteria associated with the received data operation, whether to allocate a cache slot in the cache for the received data operation. The criteria for the first family includes a minimum value and a maximum value used in determining a cache partition size range for the first family. The maximum value is used in determining a maximum cache partition size allowable for the first family.

Abstract: In a method for testing computer code, each branch that occurs within the machine-readable code is located. A first tracepoint is placed immediately after the beginning of the branch and a second tracepoint at the target address of each branch, each tracepoint generating an indicator. When the machine-readable code with the tracepoints is executed on the target computer, the method identifies those indicators that have been generated by their corresponding tracepoints, thereby permitting determination of those branches that the program control flow has not passed through. The test cases are modified to exercise the previously omitted branches, and the converted code is re-executed, until all branches have been properly exercised. The tracepoints are automatically eliminated after they have performed their intended function.

Abstract: A method for controlling exclusive access to a resource shared by multiple processors in a data storage system includes providing a system lock procedure to permit a processor to obtain a lock on the shared resource preventing other processors from accessing the shared resource and providing a faked lock procedure to indicate to the system lock procedure that a processor has a lock on the shared resource where such a lock does not exist, and wherein the faked lock procedure prevents another processor from obtaining the lock on the shared resource, but does not prevent other processors from accessing the shared resource. A data storage system according to the invention includes a shared resource, a plurality of processors coupled to the shared resource through a communication channel, and a lock services procedure providing the system lock procedure and the faked lock procedure.

Abstract: A debugger mechanism that provides for debugging source code of a target by correlating messages in a log file associated with source code with corresponding lines of the source code.