Abstract: A method of operating a storage system is disclosed. The method includes determining a storage cluster among storage arrays of the storage system. Each storage array includes at least two controllers and at least one storage shelf. The at least two controllers are configured to function as both a primary controller for a first storage array and a secondary controller for a second storage array.

Abstract: A method of operating a storage system is disclosed. The method includes determining a storage cluster among storage arrays of the storage system. Each storage array includes at least two controllers and at least one storage shelf. The at least two controllers are configured to function as both a primary controller for a first storage array and a secondary controller for a second storage array.

Abstract: A method of operating a storage system is disclosed. The method includes determining a storage cluster among storage arrays of the storage system. Each storage array includes at least two controllers and at least one storage shelf. The at least two controllers are configured to function as both a primary controller for a first storage array and a secondary controller for a second storage array.

Abstract: A method of operating a storage system is disclosed. The method includes determining a storage cluster among storage arrays of the storage system. Each storage array includes at least two controllers and at least one storage shelf. The at least two controllers are configured to function as both a primary controller for a first storage array and a secondary controller for a second storage array.

Abstract: A method of operating a storage system is disclosed. The method includes determining a storage cluster among storage arrays of the storage system. Each storage array includes at least two controllers and at least one storage shelf. The at least two controllers are configured to function as both a primary controller for a first storage array and a secondary controller for a second storage array.

Abstract: Methods for providing metrics for a plurality of storage entities of a multi-array data storage system are disclosed. As a part of a method, data representing storage characteristics from one or more storage entities is collected and a selection of a storage entity of the one or more storage entities is allowed. Responsive to the selection, a value is presented that is indicative of a predicted impact on the selected storage entity when data migration is performed. The predicted impact is determined based on the amount of shared data between the selected entity and at least one other storage entity.

Abstract: A method of operating a storage system is disclosed. The method includes determining a storage cluster among storage arrays of the storage system. Each storage array includes at least two controllers and at least one storage shelf. The at least two controllers are configured to function as both a primary controller for a first storage array and a secondary controller for a second storage array.

Abstract: A method of operating a storage system is disclosed. The method includes determining a storage cluster among storage arrays of the storage system. Each storage array includes at least two controllers and at least one storage shelf. The at least two controllers are configured to function as both a primary controller for a first storage array and a secondary controller for a second storage array.

Abstract: A system and method for efficiently caching metadata in a storage system. Addresses from a plurality of I/O accesses to the storage system are captured and then a frequency domain representation of the addresses is generated. The frequency domain representation is used to measure the randomness of the various applications which are accessing the storage system. Scores are generated based on the measure of randomness, and scores are assigned to the various regions of the logical address space. Scores are then assigned to the metadata pages which are stored in the cache based on the region of the logical address space to which the metadata pages correspond. The scores are used when determining which metadata pages to evict from the cache. The cache will attempt to evict those metadata pages which correspond to regions of the logical address space that are servicing random I/O accesses.

Abstract: A system and method for efficiently caching metadata in a storage system. Addresses from a plurality of I/O accesses to the storage system are captured and then a frequency domain representation of the addresses is generated. The frequency domain representation is used to measure the randomness of the various applications which are accessing the storage system. Scores are generated based on the measure of randomness, and scores are assigned to the various regions of the logical address space. Scores are then assigned to the metadata pages which are stored in the cache based on the region of the logical address space to which the metadata pages correspond. The scores are used when determining which metadata pages to evict from the cache. The cache will attempt to evict those metadata pages which correspond to regions of the logical address space that are servicing random I/O accesses.

Abstract: While discharging a data chunk, the chunk is compressed into a storage block. If the chunk is found to be too large to be able to be completely compressed into the storage block, certain characteristics of the data chunk are examined to determine whether or not the data chunk should be split. If the data chunk should be split, a remaining portion of the data chunk is compressed to a storage block that is next in chronological order to the original storage block. If the data chunk should not be split, all of the data chunk is moved to the next chronological storage block while leaving any remaining space in the storage block as unused.

Abstract: While discharging a data chunk the chunk is compressed into a storage block. If the chunk is found to be too large to be able to be completely compressed into the storage block certain characteristics of the data chunk are examined to determine whether or not the data chunk should be split. If the data chunk should be split, a remaining portion of the data chunk is compressed to a storage block that is next in chronological order to the original storage block. If the data chunk should not be split, all of the data chunk is moved to the next chronological storage block while leaving any remaining space in the storage block as unused.

Abstract: Delay commands are injected into sequential input/output (I/O) requests and the effects of the injected delay commands are measured for determining whether a storage system handling the sequential input/output (IO) requests is causing a bottleneck, while the processing of sequential I/O requests is delayed for a time period when injecting the delay command.

Abstract: Systems, methods, and computer readable storage mediums for optimistically managing compressed data in a storage system. When possible, multiple input blocks are compressed into a buffer and stored in a single physical block on a storage device. The metadata of the multiple input blocks can be managed separately. A fingerprint of the compressed buffer can be generated and used as an index to the single physical block. Alternatively, fingerprints of the uncompressed input blocks can be generated, and reference counts can be maintained to track the number of input blocks which reference the compressed buffer.

Abstract: For efficiently storing and retrieving data and metadata in phases, in a first phase, metadata tokens, which are assigned to metadata-emitting entities, are used for storing the data and the metadata together in a single input/output operation while piggybacking the metadata of least active metadata-emitting entities onto one of the metadata-emitting entities having one of the metadata tokens. In a second phase, the metadata is re-written to a metadata delta journal for reclaiming the metadata tokens. In a third phase, the metadata journal is applied to a metadata structure containing the metadata of the storage system, the metadata delta journal is then cleared after successfully updating the main metadata structure with the metadata of the metadata journal. The metadata journal is swapped with an empty metadata journal for concurrently adding metadata while retaining the metadata journal until applying the metadata delta journal to the metadata structure.

Abstract: Systems and methods for determining when to allow a temporary compromise on redundancy in a storage system. When servicing write requests, the storage system may utilize data redundancy techniques when writing data to backend storage devices. The operating conditions of the storage system are tracked and early acknowledgements for write requests may be permitted when the storage system is healthy enough. If the number of unacknowledged writes is greater than a programmable threshold, then early acknowledges may be prohibited. Also, if the number of ongoing rebuild processes is greater than a programmable threshold, then early acknowledges may be prohibited.

Abstract: For combining virtual mapping metadata and physical space mapping metadata in a storage system by a processor device in a computing environment, data and metadata are maintained into separate virtual streams. The separate virtual streams include a metadata stream for the metadata and a data stream for the data. Metadata for each input/output (I/O) operation received is determined using a linear function operation, the function operation being an offset of the metadata in the metadata stream that is equal to the I/O operation multiplied by a maximal metadata ratio. The metadata is allocated on the metadata stream and the metadata stream is divided into fixed size block that is responsible for describing a size of a logical space, where the logical space is equal to one divided by the maximal metadata ratio, and it is determined if the metadata has been previously loaded.

Abstract: For combining virtual mapping metadata and physical space mapping metadata in a storage system by a processor device in a computing environment, data and metadata are maintained into separate virtual streams. The separate virtual streams include a metadata stream for the metadata and a data stream for the data. Metadata for each input/output (I/O) operation received is determined using a linear function operation, the function operation being an offset of the metadata in the metadata stream that is equal to the I/O operation multiplied by a maximal metadata ratio. The metadata is allocated on the metadata stream and the metadata stream is divided into fixed size block that is responsible for describing a size of a logical space, where the logical space is equal to one divided by the maximal metadata ratio, and it is determined if the metadata has been previously loaded.

Abstract: Systems capable of transformation of logical data objects for storage and methods of operating thereof are provided. One method includes identifying among a plurality of requests addressed to the storage device two or more “write” requests addressed to the same logical data object, deriving data chunks corresponding to identified “write” requests and transforming the derived data chunks, grouping the transformed data chunks in accordance with the order the requests have been received and in accordance with a predefined criteria, generating a grouped “write” request to the storage device, and providing mapping in a manner facilitating one-to-one relationship between the data in the obtained data chunks and the data to be read from the transformed logical object. The method further includes obtaining an acknowledging response from the storage device, multiplying the obtained acknowledging response, and sending respective acknowledgements to each source that initiated each respective “write” request.

Abstract: Systems capable of transformation of logical data objects for storage and methods of operating thereof are provided. One method includes identifying among a plurality of requests addressed to the storage device two or more “write” requests addressed to the same logical data object in a distributed network, deriving data chunks corresponding to identified “write” requests and transforming the derived data chunks, grouping the transformed data chunks in accordance with a predefined criteria, generating a grouped “write” request to the storage device, and providing mapping in a manner facilitating one-to-one relationship between the data in the obtained data chunks and the data to be read from the transformed logical object. The method further includes obtaining an acknowledging response from the storage device, multiplying the obtained acknowledging response, and sending respective acknowledgements to each source that initiated each respective “write” request.