Emc IP Holding Company LLC

Emc Corporation

Edward S Robins

Evgeny Malkevich

Kevin Granlund

Stephen Richard Ives

Seema G Pai

Roii Raz

Barak Bejerano

Dan Aharoni

Andrew Chanler

Prakash Venkatanarayanan

Hagay Dagan

Michael Garvey

Dale R Elliott

Sergey Rytenkov

Krishnamoorthy Anantharaman

A distributed network of storage elements (DNSE) is provided in which the physical capacity of each drive is split into a set of equal sized logical splits which are individually protected within the DNSE using separate RAID groups. To reduce restoration latency, members of the RAID groups having a member in common on a given drive are spread within the DNSE to minimize the number of sets of drives within the DNSE that have RAID members in common. By causing the splits to be protected by RAID groups, restoration of the splits may occur in parallel involving multiple drives within the DNSE. By minimizing the overlap between RAID members on various drives, failure of a given drive will not require multiple reads from another drive in the DNSE. Likewise, spare splits are distributed to enable write recovery to be performed in parallel on multiple drives within the DNSE.

Allocating RAID storage volumes across a distributed network of storage elements

Configuring spare sections in a system having a plurality of devices and having a plurality of erasure encoding groups, each of the devices having a plurality of sections and each of the groups having a plurality of members located on the sections of the devices, includes configuring the system to have a plurality of erasure encoding groups with no spare sections, ordering the groups according to desirability of converting members of each of the groups into spare sections, converting members of a subset of the groups into spare sections according to ordering of the groups, and determining if the spare sections for the system provide sufficient coverage for the system in response to failure of each of the devices. The erasure encoding may be a RAID encoding.

Optimizing spare capacity and spare distribution

Individual storage devices of a RAID group are monitored for faults. A health indicator for each storage device is calculated based on fault growth rate. Non-failed storage device are swapped out based on the health indicator. Techniques for monitoring the storage devices include background media scans and growth list polling.

RAID failure prevention

Embodiments are directed to techniques for techniques for selecting a proper set of spare sections to use in a given failure scenario. These embodiments use a set of rules to define which spare sections are eligible to serve as spares for reconstruction of the RAID members on a disk that had failed. In addition, the set of rules may include weighted rules to allow optimization in the spare selection process.

Spare selection in a declustered RAID system

Described are techniques for selecting a storage pool configuration. A set of one or more candidate storage pool configurations is determined. For each of the candidate storage pool configurations of the set, a reliability calculation is performed to determine a reliability value indicating reliability of the candidate storage pool configuration. For each of the candidate storage pool configurations of the set, an availability calculation is performed to determine an availability value indicating availability of the candidate storage pool configuration. In accordance with selection criteria, one of the candidate storage pool configurations of the set for a first storage pool is selected. The selection criteria includes the availability value and the reliability value for each of the plurality of candidate storage pool configurations.

Techniques for reliability and availability assessment of data storage configurations

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Winchester, MA, United States of America

Edward S Robins