Boot Loader Management for Virtual Hard Disk Updates

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Solution Overview

Problem

Existing operating system update methods are prone to high failure rates, lack control, and are undeterministic, leading to issues with state synchronization and costly factory resets, especially when updating multiple devices with varying states.

Innovation Solution

Implementing zero touch management using native boot virtual hard disks (VHDs) with an enhanced write filter (EWF) in RAM mode, allowing for controlled software changes by creating reset, last known good, and current boot loaders that point to parent or child VHDs, enabling efficient updates and resets while protecting the master image from writes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an update service is invoked to change the operating system state, then the operating system can be updated, but the failure rate is high and control is lost

Engineering Contradiction:

Improveupdate reliabilityVSAvoidupdate control

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The operating system image is segmented into a master image and multiple snapshot images. The boot loader can selectively boot from different snapshots, allowing controlled updates by creating new snapshots rather than modifying the running system. This segmentation isolates update operations from the running system, reducing failure impact and improving reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system creates snapshot images before applying updates, preserving the previous state. This preliminary action allows the system to prepare updates in advance, test them, and revert if needed, thereby maintaining control over the update process and reducing failure risk.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If an entire image of the operating system is installed, then the system state can be changed, but the operation is costly and time-consuming

Engineering Contradiction:

Improveupdate speedVSAvoidupdate time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

Instead of installing entire operating system images, the system uses incremental snapshots that capture only the changes made since the parent image. This segmentation allows rapid deployment of updates by applying small snapshot files rather than large complete images, significantly improving update speed and reducing time loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system uses copy-on-write technology where snapshots are created by copying only the changed blocks from the parent image. This allows rapid creation of update images without copying the entire operating system, thereby improving productivity while minimizing time loss.

Inventive Principle:

Principle #26Copying

3Reliability

If the operating system image is dirtied and a factory reset is performed, then the system can be restored, but the operation is very costly

Engineering Contradiction:

Improvesystem restorationVSAvoidreset cost

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system maintains multiple snapshot images including a last known good snapshot before performing any restoration. This preliminary preparation allows direct booting into a known good state without requiring a full factory reset, thereby maintaining reliability while dramatically reducing the cost and time of restoration operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system prepares backup snapshot images in advance that represent known good states. These cushioning snapshots act as safety nets, allowing the system to recover from dirtied images by booting into a preserved snapshot rather than performing costly factory resets, thus protecting against restoration costs.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Adaptability or versatility

If updates are applied to a fleet of devices in multiple states, then each device can be updated, but it is difficult to bring devices to a known state

Engineering Contradiction:

Improvefleet update capabilityVSAvoidstate management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The snapshot-based update mechanism provides a universal solution that works regardless of the device's current state. Any device can be updated by applying snapshots to its boot loader, and any device can be restored by booting from any snapshot. This multi-functional approach simplifies fleet-wide updates while maintaining adaptability to different device states, reducing management complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9141368B2Managing boot loaders for virtual hard disks

Publication Date: 2015.09.22 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

The claimed subject matter provides a system or method for managing software changes. An exemplary method comprises creating a reset boot loader, a last known good (LKG) boot loader, and a current boot loader, then pointing the reset boot loader, LKG boot loader, and current boot loader to a parent virtual hard disk (VHD) containing a default master image. An operation to perform is determined, and a service partition is booted into. The LKG boot loader or current boot loader is pointed to a child VHD loaded with another desired image based on the operation selected, and the system is rebooted into the parent VHD or child VHD pointed to by the current boot loader.