Emc IP Holding Company LLC

International Business Machines Corporation

Nir Milstein

Itay Keller

Ori Shalev

Jonathan Fischer-Toubol

Yonatan Shtarkman

Omer Haklay

Erez Webman

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

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.

Storage system implementing snapshot longevity ranking for efficient management of snapshots

Techniques are provided for managing incompressible data in a compression-enabled log-structured array storage system. A log-structured array is implemented in a block storage device having a physical storage space divided into logical data blocks (e.g., fixed-size allocation units), wherein the log-structured array includes a log segment which includes a set of contiguous logical data blocks of the physical storage space. When a write request is received to store data, if the received data is deemed compressible, the data is compressed and written in a log entry in the log segment of the log-structured array. If the data is deemed incompressible, the data is written without compression in a log entry in the log segment of the log-structured array such that the log entry which stores the data without compression is write-aligned to at least one logical data block of the set of contiguous logical data blocks of the log segment.

Managing incompressible data in a compression-enabled log-structured array storage system

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.

Self-detecting storage bottleneck while handling sequential I/O operations

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.

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Tel Aviv, Israel

Nir Milstein