Emc IP Holding Company LLC

Tal Zohar

Nimrod Shani

Leron Fliess

Nadav Krispin

A method is disclosed for recovering metadata, the method comprising: identifying a corrupt or missing metadata entry, the corrupt or missing metadata entry being part of a mapping structure that is stored in a random-access memory (RAM) of a storage system; selecting a metadata backup page that is associated with the mapping structure; identifying a plurality of copies of the selected metadata backup page; identifying a most recent copy among the plurality of copies of the selected metadata backup page; and recovering the corrupt or missing metadata entry based on the most recent one of the plurality of copies of the metadata backup page.

Method to recover metadata in a content aware storage system

A method is disclosed for recovering data, the method comprising: retrieving a mapping structure associated with a volume in a storage system, the mapping structure including a plurality of entries, each entry including a respective short hash digest of a data block stored in the volume and an identifier of a location where the data block is stored; generating a plurality of long hash digests, each of the long hash digests being generated based on a different one of a plurality of data blocks that are stored in the storage system; comparing each of the long hash digests to a short hash digest of a missing data block, and adding the long hash digest to a candidate list when the long hash digest matches the short hash digest of the missing data block; generating a filtered candidate based on the candidate list; and recovering the missing data.

User data recovery in a content aware storage system

A storage system in one embodiment comprises a plurality of storage devices and a storage controller. The storage controller is configured to scan data pages and associated metadata structures of the storage system, the metadata structures comprising at least a first metadata structure associating unique hash identifiers with physical locations of respective data pages in the storage system and a second metadata structure associating the physical locations of respective data pages with hash digests of the data pages and the unique hash identifiers. The storage controller is further configured to detect an error in one of the first and second metadata structures. Responsive to the detected error, the storage controller recovers a corresponding portion of the metadata based at least in part on one or more entries of the other one of the first and second metadata structures. The unique hash identifiers illustratively comprise respective shortened representations of the hash digests, such as hash handles uniquely corresponding to respective ones of the hash digests.

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Tel Aviv, Israel

Tal Zohar