Guest OS Snapshot Storage in External Block Devices
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Solution Overview
Problem
Existing OS reversion mechanisms, such as Windows' System Restore, face limitations in disk space and vulnerability to malware, as they store snapshots locally, leading to data loss and infection risks.
Innovation Solution
Creating snapshots of a guest OS volume using a copy-on-write technique and storing them in external block storage shared among virtual machines, allowing for deduplication and secure storage outside the VM's virtual disk, enabling instantaneous reversion by overlaying block mappings without data copying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If OS snapshots are stored locally on the system disk, then reversion can be performed quickly, but disk space is limited and snapshots can be infected by malware
Solution Approach 1:
The patent extracts snapshot storage from the local system disk and places it in external block storage. The snapshot data is written to external storage devices or network-attached storage, separating the snapshot repository from the host system's local disk space. This allows snapshots to be stored without consuming valuable local disk space while still enabling fast reversion operations through block-level copying.
Solution Approach 2:
The patent moves snapshot storage from a single-dimension local disk environment to a multi-dimensional storage architecture involving external block storage devices and network-attached storage. This dimensional shift allows snapshots to be stored in distributed locations while maintaining fast access through block-level operations and metadata management.
2Ease of operation
If OS snapshots are stored locally, then reversion can be performed, but the snapshots can be infected by malware and APTs
Solution Approach 1:
The patent extracts snapshot storage from the vulnerable host system environment and places it in isolated external block storage. By separating snapshot data from the host OS file system, snapshots are protected from malware and APTs that operate within the host environment. The external storage acts as a secure repository that is inaccessible to host-based threats.
Solution Approach 2:
The patent introduces external block storage as an intermediary between the host system and snapshot data. This intermediary layer provides security isolation, preventing direct access to snapshots by malware running on the host. The system manages snapshots through controlled interfaces that mediate all access operations, blocking malicious access while enabling legitimate reversion operations.
3Quantity of substance
If snapshot storage is limited to a percentage of available space, then local disk space is preserved, but older snapshots are deleted and cannot be reverted
Solution Approach 1:
The patent extracts snapshot storage from local disk constraints and places it in external block storage with significantly larger capacity. This extraction removes the percentage-based storage limitation, allowing snapshots to be retained indefinitely in external storage while preserving full local disk space for operational use. The external storage acts as an unlimited archive for historical snapshots.
Solution Approach 2:
The patent transitions from a constrained single-dimension local storage model to a multi-dimensional storage architecture incorporating external block storage and network-attached storage. This dimensional expansion provides virtually unlimited space for snapshot retention, allowing the system to maintain extensive snapshot histories without impacting local disk availability.
4Quantity of substance
If snapshots are stored in external block storage, then disk space limitations are overcome and security is enhanced, but reversion may take longer
Solution Approach 1:
The patent segments snapshot data into blocks and manages them as discrete units in external storage. This block-level segmentation enables efficient copy operations during reversion, where only the necessary blocks are copied rather than entire snapshot images. The segmented block structure optimizes I/O operations and reduces reversion time despite external storage distances.
Solution Approach 2:
The patent replaces traditional file-level snapshot operations with block-level operations in external storage. This substitution of the operational mechanism (from file-based to block-based) significantly improves reversion speed, as block operations are more efficient and can be performed parallelly. The block storage interface provides optimized data transfer paths that compensate for external storage distances.
Data Source
AI summary
Techniques disclosed herein provide an approach for creating snapshots and reverting to the same for virtual machine (VM) guest operating systems (OSes). In one embodiment, a snapshot module in a guest OS receives blocks for a snapshot of a guest OS volume. In turn, the snapshot module creates a snapshot file in a repository external to a virtual disk of the VM, and writes the received blocks to the external repository. By storing snapshot content outside the virtual disks of VMs, disk space limitations in local VM disks can be overcome, and it is also more difficult for malicious software to modify the snapshots and infect them. To reduce storage space requirements, snapshots stored in the external repository may be deduplicated with other snapshots stored therein, including snapshots from guest OSes running in other VMs and/or a host OS on which a hosted hypervisor runs.