Netapp, Inc.

Song Guen Yoon

Dheeraj Raghavender Sangamkar

Emalayan Vairavanathan

Yi Zhang

Raymond Yu Shun Mak

Chia-Chen Chu

Robin Mahony

Alvis Yung

Aditya Kalyanakrishnan

A system, method, and machine-readable storage medium for restoring a data object for a specified active time period are provided. In some embodiments, the method includes receiving, by a storage device from a client, a request specifying an active time period for a data object to remain stored on an accessible tier. The method also includes determining, by the storage device, that the active time period has elapsed. The method further includes responsive to a determination that the active time period has elapsed, sending, by the storage device, a request to a server storing the data object to move the data object from the accessible tier to an archive tier. Data objects that are stored on the accessible tier are accessible by the client, and data objects that are stored on the archive tier are inaccessible by the client.

Object tiering in a distributed storage system

A system, method, and machine-readable storage medium for analyzing a state of a data object are provided. In some embodiments, the method includes receiving, at a storage device, a metadata request for the data object from a client. The data object is composed of a plurality of segments. The method also includes selecting a subset of the plurality of segments and obtaining a segment state for each segment of the subset. Each segment state indicates whether the respective segment is accessible via a backing store. The method further includes determining a most restrictive state of the one or more segment states and sending state information to the client in response to the metadata request, the state information being derived from the most restrictive state.

Distributed storage systems frequently use a centralized metadata repository that stores metadata in an eventually consistent distributed database. However, a metadata repository cannot be relied upon for determining which erasure coded fragments are lost because of a storage node(s) failures. Instead, when recovering a failed storage node, a list of missing fragments is generated based on fragments stored in storage devices of available storage nodes. A storage node performing the recovery sends a request to one or more of the available storage nodes for a fragment list. The fragment list is generated, not based on a metadata database, but on scanning storage devices for fragments related to the failed storage node. The storage node performing the recovery merges retrieved lists to create a master list indicating fragments that should be regenerated for recovery of the failed storage node(s).

Erasure coding repair availability

To ensure that there is an elected manager among storage nodes of an erasure coding group ('ECG'), an ECG manager ('ECGM') election process is periodically performed among available storage nodes that are configured with the software to perform the services of an ECGM. When a storage node is activated, an ECGM process of the storage node begins executing and is assigned a process identifier (&#x201c;PID&#x201d;). A storage node can utilize a service query framework to identify other available storage nodes and retrieve their ECGM PIDs. The storage node then selects a PID according to a criterion and elects the storage node corresponding to the selected PID to be the acting ECGM. This process is performed periodically, so even if the acting ECGM storage node fails, a new ECGM is eventually selected from the available storage nodes.

Manager election for erasure coding groups

To efficiently recover from a multiple storage node failure, a storage node concurrently restores data fragments to the multiple failed storage nodes, as opposed to restoring each node individually. In the VCS based storage technique, storage nodes are restored as part of an ECG repair process. For each ECG being repaired, a storage node performing the restoration process reads data fragments from active nodes in the ECG and generates new data fragments to replace any lost data fragments. The node then stores one of the new data fragments across each of the failed storage nodes. By concurrently restoring data fragments to each failed storage node, the data fragments needed to repair each ECG are only read once, thereby preserving disk operations and network bandwidth.

Growing community of inventors

Coquitlam, Canada

Song Guen Yoon