Abstract: A data storage system includes a processor, a system memory, and logical extents. Blocks of storage in one or more physical storage devices are allocated to each of the logical extents. The processor maintains a logical container for data objects and the volume includes one or more of the logical extents. The processor stores data objects that are uniquely identified by object identifiers in the logical extents. The processor also maintains a first index that is stored in the system memory and maps a range of the object identifiers to a second index. The second index is also stored in a logical extent and indicates storage locations of the data objects associated with the range of the object identifiers.

Abstract: A data storage system includes a processor, a system memory, and logical extents. Blocks of storage in one or more physical storage devices are allocated to each of the logical extents. The processor maintains a logical container for data objects and the volume includes one or more of the logical extents. The processor stores data objects that are uniquely identified by object identifiers in the logical extents. The processor also maintains a first index that is stored in the system memory and maps a range of the object identifiers to a second index. The second index is also stored in a logical extent and indicates storage locations of the data objects associated with the range of the object identifiers.

Abstract: Described herein are method and apparatus for performing wear leveling of erase-units of an LLRRM device that considers all active erase-units. Wear counts of all active erase-units (containing client data) and free erase-units (not containing client data) are tracked. Wear counts are used to determine low-wear active erase-units having relatively low wear counts and high-wear free erase-units having relatively high wear counts. In some embodiments, data contents of low-wear active erase-units are transferred to high-wear free erase-units, whereby the low-wear active erase-units are converted to free erase-units and may later store different client data which may increase the current rate of wear for the erase-unit. The high-wear free erase-units are converted to active erase-units that store client data that is infrequently erased/written, which may reduce the current rate of wear for the erase-unit. As such, wear is spread more evenly among erase-units of the LLRRM device.

Abstract: Described herein are method and apparatus for using an LLRRM device as a storage device in a storage system. At least three levels of data structures may be used to remap storage system addresses to LLRRM addresses for read requests, whereby a first-level data structure is used to locate a second-level data structure corresponding to the storage system address, which is used to locate a third-level data structure corresponding to the storage system address. An LLRRM address may comprise a segment number determined from the second-level data structure and a page number determined from the third-level data structure. Update logs may be produced and stored for each new remapping caused by a write request. An update log may specify a change to be made to a particular data structure. The stored update logs may be performed on the data structures upon the occurrence of a predetermined event.

Abstract: Described herein are method and apparatus for using an LLRRM device as a storage device in a storage system. At least three levels of data structures may be used to remap storage system addresses to LLRRM addresses for read requests, whereby a first-level data structure is used to locate a second-level data structure corresponding to the storage system address, which is used to locate a third-level data structure corresponding to the storage system address. An LLRRM address may comprise a segment number determined from the second-level data structure and a page number determined from the third-level data structure. Update logs may be produced and stored for each new remapping caused by a write request. An update log may specify a change to be made to a particular data structure. The stored update logs may be performed on the data structures upon the occurrence of a predetermined event.

Abstract: Described herein are method and apparatus for using an LLRRM device as a storage device in a storage system. At least three levels of data structures may be used to remap storage system addresses to LLRRM addresses for read requests, whereby a first-level data structure is used to locate a second-level data structure corresponding to the storage system address, which is used to locate a third-level data structure corresponding to the storage system address. An LLRRM address may comprise a segment number determined from the second-level data structure and a page number determined from the third-level data structure. Update logs may be produced and stored for each new remapping caused by a write request. An update log may specify a change to be made to a particular data structure. The stored update logs may be performed on the data structures upon the occurrence of a predetermined event.

Abstract: Described herein are method and apparatus for performing wear leveling of erase-units of an LLRRM device that considers all active erase-units. Wear counts of all active erase-units (containing client data) and free erase-units (not containing client data) are tracked. Wear counts are used to determine low-wear active erase-units having relatively low wear counts and high-wear free erase-units having relatively high wear counts. In some embodiments, data contents of low-wear active erase-units are transferred to high-wear free erase-units, whereby the low-wear active erase-units are converted to free erase-units and may later store different client data which may increase the current rate of wear for the erase-unit. The high-wear free erase-units are converted to active erase-units that store client data that is infrequently erased/written, which may reduce the current rate of wear for the erase-unit. As such, wear is spread more evenly among erase-units of the LLRRM device.

Abstract: Described herein are method and apparatus for performing wear leveling of erase-units of an LLRRM device that considers all active erase-units. Wear counts of all active erase-units (containing client data) and free erase-units (not containing client data) are tracked. Wear counts are used to determine low-wear active erase-units having relatively low wear counts and high-wear free erase-units having relatively high wear counts. In some embodiments, data contents of low-wear active erase-units are transferred to high-wear free erase-units, whereby the low-wear active erase-units are converted to free erase-units and may later store different client data which may increase the current rate of wear for the erase-unit. The high-wear free erase-units are converted to active erase-units that store client data that is infrequently erased/written, which may reduce the current rate of wear for the erase-unit. As such, wear is spread more evenly among erase-units of the LLRRM device.

Abstract: Method and apparatus for remapping addresses for a victim cache used in a storage system is provided. The storage system may store data blocks having associated storage system addresses. Blocks may be stored to a main cache and blocks evicted from main cache may be stored in the victim cache, each evicted block having a storage system address and a victim cache address where it is stored in the victim cache. Remapping data for remapping between storage system addresses to victim cache addresses may be stored in remapping data structures. The victim cache may be sub-divided into two or more sub-sections, each sub-section having an associated remapping data structure for storing its remapping data. By sub-dividing the victim cache, the bit size of victim cache addresses stored in the remapping data structures may be reduced, thus reducing the overall storage size of the remapping data for the victim cache.

Abstract: A collective storage system and method for restoring data in the system after a failure in the system. The system includes multiple storage nodes that are interconnected by a network and store data as extents. There are also a set of Data Service (DS) agents for managing the extents, a set of Metadata Service (MDS) agents for managing metadata relating to the nodes and the extents, and a Cluster Manager (CM) agent in each node. After a node failure is detected by one of the CM agents, the agents responsible for coordinating the data restoring are notified of the failure. The agents generate a plan to restore the data extents affected by the failure, and then collectively restoring the affected extents based on the generated plan. The coordinating agents might be the MDS agents or DS agents. The failure might be a node failure or a disk failure.

Abstract: A collective storage system and method for restoring data in the system after a failure in the system. The system includes multiple storage nodes that are interconnected by a network and store data as extents. There are also a set of Data Service (DS) agents for managing the extents, a set of Metadata Service (MDS) agents for managing metadata relating to the nodes and the extents, and a Cluster Manager (CM) agent in each node. After a node failure is detected by one of the CM agents, the agents responsible for coordinating the data restoring are notified of the failure. The agents generate a plan to restore the data extents affected by the failure, and then collectively restoring the affected extents based on the generated plan. The coordinating agents might be the MDS agents or DS agents. The failure might be a node failure or a disk failure.