Page History

...

CLOUDSTACK-732

Branch

4.1.0

Requirements

Hypervisor: KVM 6.3

KVM snapshot is supported for KVM 6.2. For KVM 6.3, we do not know if disk_only snapshot
is supported or not. This bug fix is to investigate this snapshot feature.

Introduction

Purpose

There are several types of snapshots:

• disk snapshot (aka external snapshot)
• VM state snapshot
• system checkpoint

Disk snapshot saves the content of the disks at a desiginated point of time;
VM state snapshot tracks only the state of RAM and all other resources in use by the VM;
system System checkpoint captures both the disk and the VM state.

The current KVM takes a long time to take a disk snapshot, where the VM can be unresponsive for several minutes. We would like to investigate and find out if the new KVM support the disk-only snapshot option.

Implementation

There are 2 tasks :

1. Investigate the disk only snapshot feature: does it work for current KVM on 4.1
2. If the disk-only snapshot is supported, then we need to use the libvert API
   to add the disk snapshot support.

On a kvm system, we need to:

• test the snapshot creation with disk-only option, and find out how long it takes;
• revert a snapshot;
• create snapshot of large disk file, or small disk files;

Command: snapshot-create-as <snapshot-name> "description" --disk-only