Storage Management System for Accurate RAID Capacity Estimation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing storage management systems face inaccuracies in estimating available storage units after rebalancing in RAID systems, leading to potential failures in allocating storage units due to miscalculations in available capacity.

Innovation Solution

A method that determines the first and second distributions of disk slices used to build storage units before and after expanding a slice pool, calculating the available number of disk slices for building new storage units, and adjusting allocations based on these distributions and effective capacities to ensure accurate capacity estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If RAID loops over all RRS and sums up available capacity to estimate storage units, then the estimation process is simple, but the estimation becomes inaccurate after rebalancing due to not considering distribution changes

Engineering Contradiction:

Improvesimplicity of capacity estimationVSAvoidaccuracy of available capacity estimation

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The system performs preliminary calculation of disk slice distributions before rebalancing occurs. By pre-calculating the first distribution of disk slices and storing it, the system can later compare it with the second distribution after rebalancing to accurately determine available capacity, avoiding the need for complex real-time recalculations while maintaining precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by comparing the first distribution (before rebalancing) with the second distribution (after rebalancing). This feedback mechanism allows the system to detect changes in disk slice allocation and adjust capacity estimation accordingly, ensuring accuracy without requiring complete re-evaluation of all RRS

Inventive Principle:

Principle #23Feedback

2Quantity of substance

If the slice pool is expanded by adding new disks and regrouping into new RRS, then storage capacity increases, but the existing allocation becomes invalid requiring rebalancing

Engineering Contradiction:

Improvetotal storage capacityVSAvoidcomplexity of disk slice reassignment

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The system segments disk slices into distinct first distribution (before expansion) and second distribution (after expansion). By dividing the reassignment process into these segments, the system can handle the complexity of disk slice reassignment systematically, calculating available capacity based on the second distribution while maintaining track of the first distribution for comparison

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adapts to pool expansion by allowing the disk slice distribution to change from the first distribution to the second distribution. This dynamic approach enables the system to accommodate new disks and adjust allocations automatically, maintaining validity of storage unit allocations after expansion without manual intervention

Inventive Principle:

Principle #15Dynamics

3Speed

If the mapper allocates storage units immediately without considering post-rebalancing distribution, then allocation speed is fast, but allocation may fail due to incorrect availability promise

Engineering Contradiction:

Improveallocation speedVSAvoidreliability of storage unit allocation

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary determination of the first distribution of disk slices before rebalancing occurs. This pre-calculated information is then used during allocation to determine the second distribution after rebalancing, allowing the mapper to quickly allocate storage units while ensuring reliability by accounting for post-rebalancing changes without requiring slow real-time recalculation

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11520512B2Method for storage management, electronic device and computer program product

Publication Date: 2022.12.06 EMC IP HLDG CO LLC

AI summary

Techniques involve determining a first slice distribution used to build first storage units in a first pool; in response to a determination that the first pool is expanded to a second pool, determining, at least based on a sum of the slices having been used to build the first storage units, a second slice distribution of updated slices used to build the first storage units in the second pool; determining, based on the first distribution and the second distribution, a first available number of slices and a second available number of slices available for building second storage units in the second pool, the second storage units being different from the first storage units; and determining, at least based on the first available number and the second available number, the number of the second storage units allowed to be built. Accordingly, available capacity allowed for building can be accurately estimated.