Iron Mountain Incorporated

Longsand Limited

Autonomy Corporation Ltd

Peter D Beaman

Robert S Newson

Tuyen M Tran

A hash table system having a first hash table and a second hash table is provided. The first hash table may be in-memory and the second hash table may be on-disk. Inserting an entry to the hash table system comprises inserting the entry into the first hash table, and, when the first hash table reaches a threshold load factor, flushing entries into the second hash table. Flushing the first hash table into the second hash table may comprise sequentially flushing the first hash table segments into corresponding second hash table segments. When looking up a key/value pair corresponding to a selected key in the hash table system, the system checks both the first and second hash tables for values corresponding to the selected key. The first and second hash tables may be divided into hash table segments and collision policies may be implemented within the hash table segments.

Hybrid hash tables

Methods and systems are disclosed that relate to single instance storage of asset parts utilizing a back reference count associated with each asset part. Entries in a journal associated with the asset parts reflect the intention to increment or decrement an asset part's back reference count. The journal may be used to maintain an accurate and reliable reference count for asset parts replicated across multiple disk drives in a distributed storage system, where the replication is structured to reduce the risk of data loss in the event of a disk drive failure. The journal entries may comprise generation numbers used to maintain a back reference count associated with an asset part and to verify a back reference count associated with an asset part.

Methods and systems for single instance storage of asset parts

In a data storage system having a plurality of storage nodes storing replicas of stripes, one storage node serves as a primary stripe node for a stripe. Client applications using the data storage system request operations affecting metadata stored in the stripe, and the data storage system creates workflow objects to implement the requested operation. Once the operation is completed, the workflow is acknowledged. A method for establishing a new primary stripe node comprises performing, by a selected storage node, a feasibility determination to determine the feasibility of the selected storage node becoming the new primary stripe node. It is feasible to become a new primary stripe node when doing so does not cause workflows that have been acknowledged, or that will be acknowledged, to result in strays.

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Newton, MA, United States of America

Peter D Beaman