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Slice Data Rebalancing Policy Based on Uniform Namespace Allocation across All Memory Devices

IP.com Disclosure Number: IPCOM000249505D
Publication Date: 2017-Mar-01
Document File: 1 page(s) / 21K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to always maintain an even namespace allocation of memory devices in a ds unit, proportionate to the capacities. The method is to move the slice data between neighboring memory devices such that the ds unit is constantly moving toward an ideal fully proportionate memory-device-capacity to namespace range allocation.

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Slice Data Rebalancing Policy Based on Uniform Namespace Allocation across All Memory Devices

As memory devices fail and are replaced with new ones, the associated slice data is migrated to the neighboring memory devices. This, however, can create a scenario in which some of the healthy memory devices are given a disproportionate fraction of the namespace as compared to other memory devices in the ds unit.

Because slice data is written uniformly across the namespace, a disproportionate amount of namespace allocation on memory devices in a ds unit results in some memory devices reaching full capacity, while other memory devices in the ds unit have unused capacity remaining, which may cause incoming writes to fail that otherwise should not have failed. Therefore, for optimal operation, the system must always maintain an even namespace allocation of memory devices in a ds unit, proportionate to the capacities. To do this in the face of failing memory devices requires an alternate strategy for rebalancing.

The novel solution is a method to move the slice data between neighboring memory devices such that the ds unit is constantly moving toward an ideal fully proportionate memory-device-capacity to namespace range allocation. To implement the solution, the ds unit executes the follow procedure:

1. Calculate an ideal memory-device-capacity to namespace range mapping based on the total namespace range(s) for which the ds unit is responsible, and the total storage capacity of each...