Capturing Snapshots in OpenShift Virtualization
In this blog, we’ll explore how snapshots are created and managed in OpenShift Virtualization.
Introduction
In OpenShift Virtualization, snapshots play a critical role in the protection and management of virtual machines by enabling point-in-time capture of the entire VM state. This includes the operating system, active applications, all attached storage volumes, and configuration parameters. By preserving this comprehensive state, snapshots provide a reliable safety net, particularly beneficial for developers and system administrators.
They allow users to establish a known-good baseline before performing updates, testing new features, or making significant system changes. In the event of unexpected errors or failures, snapshots allow users to quickly revert to a stable state, thereby minimizing downtime and reducing the risk of data loss or service disruption.
Why Use Snapshots?
Snapshots are especially useful for developers and administrators who:
- Want to experiment or update VMs without risking existing setups.
- Allows for quick restoration to a known-good configuration when system issues occur.
- Are running critical workloads that require data consistency and recovery points.
Types of Snapshots
OpenShift Virtualization supports two snapshot modes.
- Live Snapshots taken during VM runtime
- Offline Snapshots (while the VM is powered off)
During live snapshots, OpenShift uses the QEMU guest agent within the VM to quiesce the file system, helping ensure data consistency. If the guest agent isn’t installed, snapshots can still be taken, but there’s a risk of file system inconsistency.
Storage Considerations: The ability to use snapshots largely relies on the underlying storage backend. For example:
- Red Hat OpenShift Data Foundation (ODF) provides comprehensive support for snapshot operations
- Some other storage providers may not support CSI-based snapshots, which can restrict functionality.
Advantages of Snapshots in OCP Virtualization:
- Point-in-Time Recovery
- Supports Live and Offline Snapshots
- Data Consistency with Guest Agent
- Preserves Full VM Configuration
- Disaster Recovery Preparedness
- Supports Hot-Plugged Disks
- Simplifies Backup and Restore
In conclusion, VM snapshots in OpenShift Virtualization constitute a critical mechanism for managing lifecycle events in virtualized environments, particularly when supported by a compatible capturing storage backend and the effective deployment of the QEMU guest agent.
