Emc IP Holding Company LLC

Emc Corporation

Barak Bejerano

Stephen Richard Ives

Adi Ofer

Rong Yu

Peng Yin

Gilad Sade

Seema G Pai

Evgeny Malkevich

Edward S Robins

Kevin Granlund

Roii Raz

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

Scheduling jobs for a plurality of logical devices associated with physical devices includes assigning a physical run count value and a physical skip count value to each of the physical devices, at each iteration, examining the physical skip count value and the physical run count value for each of the physical devices, and scheduling a number of jobs up to the physical run count value for logical devices associated with a particular one of the physical devices at each iteration corresponding to the physical skip count value for the particular one of the physical devices. The physical skip count value and the physical run count value for a particular one of the physical devices may vary according to a total load of the particular physical device. The total load of the particular physical device may vary according to a number of jobs for all logical devices associated with the particular physical device and a total number of all jobs for all physical devices associated with a particular physical device controller.

Physical based scheduler using run count and skip count values

Scheduling jobs for a plurality of devices includes assigning a run count value to each of the devices, scheduling a number of consecutive jobs up to the run count value, and decrementing the run count value according to the number of consecutive jobs scheduled. The run count value for a particular one of the devices may vary according to a total load of the particular one of the devices. The total load of the particular device may vary according to a number of pending jobs for the particular device and a total number of jobs for all devices coupled to a controller for the devices. The devices may be disk drive devices. Only one read job may be scheduled for a device irrespective of the run count value for the device and devices having pending read jobs may be given precedence over other devices. Multiple read jobs may be scheduled for a device according to the run count value and devices having pending read jobs may be given precedence over other devices. The disk drive devices may be subdivided into a plurality of logical devices.

Consecutive scheduling of jobs for a device using run count values

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Barak Bejerano