Emc IP Holding Company LLC

Yonatan Shtarkman

Itay Keller

Erez Webman

Nir Milstein

Asaf Porath

Michal Yarimi

Techniques are provided for utilizing snapshot longevity information to manage snapshots in a snapshot-enabled storage system. A snapshot management system generates a snapshot volume tree which comprises snapshots associated with a given storage volume. The snapshot management system obtains a snapshot policy associated with the given storage volume, which comprises a snapshot creation and retention schedule that specifies retention lifespans of the snapshots. The snapshot policy is evaluated to automatically determine and assign respective longevity ranking values for the snapshots within the snapshot volume tree, wherein the longevity ranking value of a given snapshot represents a retention lifespan of the given snapshot as compared to retention lifespans of other snapshots as represented by their respective longevity ranking values. When a snapshot is deleted, the assigned longevity ranking values of the snapshots are utilized to select a snapshot to assume ownership of uniquely-written data that is owned by the deleted snapshot.

Assignment of longevity ranking values of storage volume snapshots based on snapshot policies

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 utilizing snapshot longevity information to manage snapshots of storage volumes in a snapshot-enabled storage system. A snapshot management system maintains a snapshot volume tree which comprises a plurality of snapshots having respective longevity ranking values. The longevity ranking value of a given snapshot represents an expected life span of the given snapshot as compared to expected life spans of other snapshots as indicated by their respective longevity ranking values. When a snapshot is deleted, the snapshot management system determines a set of candidate snapshots which can assume ownership of uniquely-written data of the deleted snapshot, evaluates the longevity ranking values of the candidate snapshots to select a candidate snapshot to assume ownership of the uniquely-written data of the deleted snapshot, and modifies metadata of the selected snapshot to transfer the ownership of the uniquely-written data from the deleted snapshot to the selected snapshot.

Growing community of inventors

Tel Aviv, Israel

Yonatan Shtarkman