Virtual Hard Disk Streaming via Differencing File Segmentation

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Solution Overview

Problem

Current virtual desktop deployments rely on expensive Storage Area Networks (SANs) for centralized storage of virtual hard disk files, which is costly and inefficient, especially when multiple users attempt to log on simultaneously, leading to significant latency in booting guest operating systems.

Innovation Solution

A system and method for deploying virtual hard drives that utilize a commodity server with local storage, where virtual hard disk files are broken into differencing files and selectively cached across the datacenter, allowing booting from local storage instead of centralized storage, thereby reducing network traffic and latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If centralized storage using SAN is used, then virtual hard disk files can be stored and accessed remotely, but the cost increases and network bandwidth is consumed

Engineering Contradiction:
Improveremote access capabilityVSAvoidstorage infrastructure cost
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The virtual hard disk files are divided into multiple differencing files (e.g., base image, first difference, second difference) that can be selectively cached and downloaded. This segmentation allows the system to use commodity servers with local storage instead of expensive SAN infrastructure, as each file can be independently managed and cached at edge locations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates copies of virtual hard disk files at multiple locations including centralized servers and edge cache servers. These copies are then selectively downloaded to virtualization hosts based on demand, eliminating the need for expensive SAN storage while maintaining remote access capability through the copied files distributed across the network.

Inventive Principle:
Principle #26Copying

2Adaptability or versatility

If multiple users log on simultaneously to centralized storage, then resource sharing is enabled, but latency increases due to network traffic

Engineering Contradiction:
Improvemulti-user accessVSAvoidboot speed
Core Design Contradiction:
Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent implements local caching of differencing files at edge servers and virtualization hosts. Instead of all users accessing the centralized SAN storage simultaneously, each user gets local copies of the required differencing files from nearby edge servers, dramatically reducing network latency and boot times while still enabling multi-user access through the distributed cache network.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system pre-loads and caches differencing files at edge servers and virtualization hosts before users need to log on. This preliminary action ensures that when multiple users attempt to log on simultaneously, the required files are already available locally, eliminating network latency delays and enabling instant booting.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If virtual hard disk files are streamed from centralized storage, then dynamic deployment is enabled, but network bandwidth is consumed and latency increases

Engineering Contradiction:
Improvedynamic instantiationVSAvoidnetwork bandwidth consumption
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The virtual hard disk is segmented into a base image and multiple differencing files that can be independently cached at edge locations. This segmentation enables dynamic deployment by allowing the system to serve different combinations of base image and differencing files from local cache servers rather than streaming everything from centralized storage, significantly reducing network bandwidth consumption.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent distributes copies of differencing files to edge cache servers and virtualization hosts in advance. When dynamic deployment is needed, the system assembles the required virtual machine by combining local copies of the base image and relevant differencing files, eliminating the need to stream large portions of data over the network and reducing bandwidth consumption.

Inventive Principle:
Principle #26Copying

4Device complexity

If commodity servers with local storage are used instead of SAN, then cost decreases, but storage capacity and reliability are reduced

Engineering Contradiction:
Improvestorage infrastructure costVSAvoidstorage reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent creates multiple copies of virtual hard disk files (base image and differencing files) that are distributed across centralized servers and edge cache servers. This redundancy ensures that if one storage location fails, other copies remain available, maintaining high reliability while using cost-effective commodity servers with local storage instead of expensive SAN infrastructure.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The system performs preliminary actions by pre-caching multiple copies of differencing files at edge servers and virtualization hosts. This advance preparation ensures continuous operation even if centralized storage experiences failures, as local copies are immediately available. The preliminary caching of redundant copies maintains reliability while using affordable storage hardware.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2622460B1Techniques for streaming virtual machines from a server to a host
Publication Date: 2024.10.30 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP2622460B1 patent drawingFigure 1
  • EP2622460B1 patent drawingFigure 2
  • EP2622460B1 patent drawingFigure 3

AI summary

Techniques for configuring a commodity server to host virtual hard disks are disclosed herein. In an exemplary embodiment, a virtual hard disk file can be split into a plurality of differencing VHD files and one or more of the files can be downloaded to a virtualization host as it runs off the VHD files stored on the server. After the one or more VHD files are downloaded, the virtualization host can be configured to use the local copy instead of the copy on the commodity server. In addition to the foregoing, other techniques are described in the claims, the detailed description, and the figures.