Emc IP Holding Company LLC

Asaf Porath

Itay Keller

Michal Yarimi

Yonatan Shtarkman

Doron Tal

Erez Webman

Dvir Koren

Zeev Shusterman

Neta Peleg

Yoav Peled

Techniques are provided to recover from partial device errors of storage devices in a data storage system. A storage control system manages a storage device which comprises storage capacity that is logically partitioned into segments of equal size. The storage control system groups at least some of the segments of the storage device into a segment group. Each segment of the segment group is configured to store one or more data items and associated metadata items. The storage control system generates a parity data segment based on the segments of the segment group, and persistently stores the parity data segment in association with the segment group. In response to detecting a storage device error associated with a corrupted segment of the segment group, the storage control system utilizes the parity data segment and non-corrupted segments of the segment group to recover at least one missing data item of the corrupted segment.

Recovery from partial device error in data storage system

An apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The apparatus is configured to maintain a snapshot tree data structure having a plurality of volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume. The apparatus is further configured to receive a request to read a data item from a given volume offset of a particular one of the volume nodes, to determine a set of data descriptors for the given volume offset, to determine a set of volume nodes of interest for the particular volume node, to determine a contribution set based at least in part on the set of data descriptors and the set of volume nodes of interest, to determine a read address for the data item as a function of the contribution set, and to read the data item from the read address.

Snapshot-enabled storage system implementing algorithm for efficient reading of data from stored snapshots

An apparatus in an illustrative embodiment comprises at least one processing device comprising a processor coupled to a memory. The apparatus is configured to maintain a snapshot tree data structure having a plurality of volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume. The apparatus is further configured to determine a set of data descriptors for a given volume offset, to determine a set of reader volume nodes that are readers of a corresponding data item based at least in part on the set of data descriptors, to adjust one or more of the data descriptors in the set of data descriptors based at least in part on the set of reader volume nodes, and to reclaim storage space previously allocated to the data item responsive to the adjusting of the one or more data descriptors.

Snapshot-enabled storage system implementing algorithm for efficient reclamation of snapshot storage space

Techniques are provided for managing snapshot volume trees in a snapshot-enabled data storage system. A snapshot management system is configured to maintain a snapshot volume tree for a storage volume of a storage system, wherein the snapshot volume tree comprises a data structure which comprises a plurality of snapshot volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume, wherein the snapshot volume nodes comprise respective generation times which denote times that the respective snapshot volume nodes were created. The generation times are used in conjunction with write times of data items that are written to the snapshot volume nodes to manage snapshot reading and deletion operations.

Growing community of inventors

Tel Aviv, Israel

Asaf Porath