Creating a Snapshot
Create a snapshot to save an image of a virtual machine (VM) or of selected volumes on a VM at a particular point in time. You can use a snapshot to create a new VM on the same everRun system or you can export the snapshot to files on a network share for use on another everRun system. By default, the everRun system's ability to take snapshots is enabled. To disable or to re-enable the system's ability to take snapshots, see Disabling and Enabling Snapshots. For an overview of snapshots, see Managing Snapshots.
You can create a snapshot of a VM whether the VM is running or shut down; however, if you want to create an application-consistent snapshot, where supported applications quiesce or freeze their operations to ensure data consistency, you must prepare your guest operating system as described in one of the following topics:
- Installing the QEMU Guest Agent for Application-Consistent Snapshots (Windows-based VMs)
- Installing the QEMU Guest Agent for Application-Consistent Snapshots (Linux-based VMs)
The number of snapshots you can create depends on the amount of storage space you have allocated in the volume container for each VM volume, as described in Sizing Volume Containers. If necessary, you can expand a volume container as described in Expanding a Volume Container on the everRun System.
- For Linux-based VMs, if you want to create a snapshot of the VM to export to another system, consider editing the /etc/fstab file to comment out entries for data volumes and allow only the boot volume to mount. Because Linux-based VMs may use different device names on another system, your new VM may boot into single-user mode if it cannot mount the volumes with their original device names. You can restore the /etc/fstab entries in the new VM with the correct device names after the import process.
- If you want to shut down the source VM while creating a snapshot, consider scheduling a planned maintenance period for this process.
- When you create a snapshot, all volumes are selected, by default. You can, though, change the selection of individual volumes.
- The boot volume is required for all snapshots.
- If you want to use a snapshot to duplicate a VM, and you will continue to use the source VM after the export, remember to set a different MAC address and IP address for the VM when you import it on the target system.
- If the everRun system switches from the primary PM to the secondary PM during the snapshot, the snapshot fails. This does not affect the continuous uptime of your system, but the snapshot is automatically deleted, and you need to start a new snapshot.
To prepare for creating a snapshot (Windows-based VMs only)
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If you want to create an application-consistent snapshot, ensure that the QEMU guest agent is installed and running, as described in Installing the QEMU Guest Agent for Application-Consistent Snapshots (Windows-based VMs).
- Ensure that all volumes are labeled accurately, as summarized in Managing Windows Drive Labels.
To prepare for creating a snapshot (Linux-based VMs only)
If you want to create an application-consistent snapshot, ensure that the QEMU guest agent is installed and running, as described in Installing the QEMU Guest Agent for Application-Consistent Snapshots (Linux-based VMs).
To create a snapshot
- Log on to the everRun system with the everRun Availability Console.
- On the Physical Machines page (see the Physical Machines Page), verify that both PMs are in the running state and that neither PM is in maintenance mode or in the process of synchronizing.
- On the Virtual Machines page, select a VM.
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With the VM selected, click the Snapshot button in the bottom pane.
The Snapshot Virtual Machine dialog box appears, displaying the rows Data Volumes to Capture and Boot Volume to Capture.
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In the Snapshot Virtual Machine dialog box, all volumes are selected, by default. Deactivate the check box beside volumes that you do not want to capture in the snapshot. The boot volume is required for all snapshots.
Optionally, type a Snapshot Name and Description for the snapshot. The default Snapshot Name for each new snapshot is the name of the VM, but you can type a more descriptive name. (The snapshot name does not need to be unique.)
- Click Create Snapshot. The snapshot begins, and the dialog box closes automatically.
Creating a snapshot typically takes a few seconds, but it may take longer depending on the level of VM activity and the amount of time that has passed since the previous snapshot. You can determine the status of a snapshot by checking the State column on the Snapshots page:
- A broken icon (
) indicates that a snapshot is still in progress, or that is written to only one node in the everRun system. - A normal icon (
) indicates that a snapshot is complete.
If you want to use a completed snapshot to create a new VM, see Creating a Virtual Machine from a Snapshot. If you want to export a completed snapshot, see Exporting a Snapshot.