Virtual Machine Snapshot Management for Heterogeneous Disks
Solution Overview
Problem
Current snapshot backup systems in virtualized environments face challenges such as application-awareness protection, time windows for snapshot generation, and support for heterogeneous disks, leading to potential data loss or corruption due to failed backups and incomplete snapshots.
Innovation Solution
A data protection backup system with an in-guest data protection agent and a host-level snapshot data mover coordinates snapshot generation, extends time windows for snapshot completion, and intelligently manages disk types to ensure application-consistent backups, avoiding unwanted log truncation and excluding unsupported disks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the snapshot generation is constrained to a fixed time window, then the backup process can be completed quickly, but the snapshot may fail to capture complete application data leading to data loss or corruption
Solution Approach 1:
The patent implements dynamic time window adjustment by monitoring snapshot generation progress and extending the time window when needed. The system transitions from a static fixed time window to a dynamic adaptive time window that expands based on actual snapshot generation requirements, ensuring both speed and completeness of backups.
Solution Approach 2:
The system changes the time window parameter dynamically during the backup process. When the snapshot generation is progressing slowly or is at risk of timeout, the system adjusts the time window parameter to provide additional time, thereby maintaining snapshot completeness while still aiming for efficient backup completion.
2Reliability
If all disk types are included in the snapshot, then comprehensive data protection is achieved, but unsupported disk types cause backup failures
Solution Approach 1:
The patent extracts and identifies unsupported disk types from the set of all disks attached to the virtual machine. The system separates supported disks (which are snapshotted) from unsupported disks (which are excluded), preventing backup failures while maintaining comprehensive protection for all protectable data.
Solution Approach 2:
The system applies different quality treatment to different disk types. Supported disks receive full snapshot protection while unsupported disks are excluded or handled differently. This local differentiation ensures that each disk type is processed according to its capabilities, maintaining both protection coverage and backup success rate.
3Productivity
If the copy service is given a strict time window for snapshot generation, then resource allocation is optimized, but the backup may be marked as successful when it has actually failed
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors snapshot generation progress and compares it against the time window. Based on this feedback, the system can extend the time window if the snapshot is not complete, preventing false success markings and ensuring accurate backup status reporting while maintaining efficient resource allocation.
Data Source
AI summary
An in-guest agent receives a command to conduct a backup of a virtual machine (VM) having a copy service. A discovery is initiated of disk types attached to the VM. Based on the discovery, at least first and second disks are identified. The first disk is identified as a virtual machine disk (VMDK) and the second disk is identified as a raw device mapping (RDM) disk. After the identification, a request is issued to the copy service to prepare the applications for a snapshot operation. A first request for a snapshot of the VMDK disk is issued over a socket communication channel. A second request for a snapshot of the RDM disk is issued over a TCP network to a controller of a storage array responsible for presenting the second disk to the VM. Responses to the first and second requests are managed to conduct the backup.