Dell Products Inc.

Geetha Shendge

Murthy Mamidi

Neerajkumar Nareshkumar Chourasia

Charles J Hickey

Shashikanth Lakshmikantha

Dhawal Bhagwat

Ramesh Kannan K

Recovering a namespace held in a tree structure that has been corrupted includes scanning a linear representation of pages belonging to the tree structure to copy out keys from uncorrupted leaf pages into a new tree structure. The scan is repeated over snapshots that have been taken of the tree to find keys that are missing from the new tree structure. Upon finding a missing key in an uncorrupted leaf page of a snapshot, the missing key is copied out into the new tree structure unless the missing key has already been found and copied out from an uncorrupted leaf page of a more recent snapshot taken of the tree structure.

Namespace salvage in logging-based filesystems

Delivering file system namespace features without on-disk layout changes is described. An iterator in a file system identifies an anomaly in a hierarchical data structure, which includes a root node at a highest level in a file set, includes directories of connected nodes corresponding to other levels in the file set, and includes leaf nodes at a lowest level in the file set. The iterator stores an annotation, about the anomaly, into an in-memory storage that is external to the file system. An asynchronous agent in the file system identifies the annotation, about the anomaly, which is stored in the in-memory storage, thereby enabling the asynchronous agent to correct the anomaly.

Delivering file system namespace features without on-disk layout changes

Replication of tags in global scale systems is described. A source node creates a file and a grouping tag for the file. The source node stores the grouping tag in a location in metadata for the file. When preparing for replication, the source node retrieves the grouping tag from the location in the metadata for the file. If a legacy location in the metadata for the file includes any value which was stored after a most recent replication involving the file, the source node identifies a key for the legacy location in the metadata for the file. The source node adds the grouping tag as a value for the identified key. The source node sends the metadata for the file, including the identified key, to a destination node.

Source nodes for replication of tags in global scale systems

Replication of tags in global scale systems is described. A source node creates a file and a grouping tag for the file. The source node stores the grouping tag in a location in metadata for the file. When preparing for replication, the source node retrieves the grouping tag from the location in the metadata. If the legacy location in the metadata includes any value which was stored after the most recent replication involving the file, and the size of the legacy location in the metadata was not changed after the most recent replication involving the file, the system adds the grouping tag to the legacy location in the metadata which includes any value which was stored after the most recent replication involving the file. The system sends the metadata, which includes the grouping tag and any value stored at the legacy location in the metadata, to a destination node.

Replication of tags in global scale systems

A destination node receives metadata for a file, via replication, from a source node. If a legacy location in the metadata for the file does not include any new value for a legacy location in local metadata for the file, then the destination node stores the metadata to a local data structure. If the legacy location in the metadata includes any new value for the legacy location in the local metadata, and the new value is any new grouping tag, then the destination node extracts the new grouping tag from the legacy location in the metadata. The destination node constructs a key based on the legacy location in the metadata and uses the constructed key to search for an alternative location in the metadata for the file, for the new grouping tag. The destination node stores the new grouping tag in the alternative location in the metadata.

Creating keys for replication of tags in global scale systems

A source node creates a file and a grouping tag for the file. The source node stores the grouping tag in a location in metadata for the file. When preparing for replication, the source node retrieves the grouping tag from the location in the metadata. If the legacy location in the metadata includes any value which was stored after the most recent replication involving the file, and the size of the legacy location in the metadata was changed after the most recent replication involving the file, then the system enables a destination node to store the grouping tag in the legacy location in the metadata by sending records comprising a request to replace a record stored at the legacy location in the metadata with a larger record, and combining the grouping tag with any value which changed the size of the metadata after a most recent replication involving the file.

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Geetha Shendge