Save the disk of a VM¶

Synopsis¶

pcocc save [OPTIONS] [VM]

Description¶

Save the disk of a VM to a new disk image.

By default, only the differences between the current state of the VM disk and the image from which it was instantiated are saved in an incremental file to form a new revision of the image. When a VM is instantiated it uses the latest revision of the image defined in its template. The -d option allows to create a new image instead of a new revision of the current image. The --full flag allows to make the new image or revision from a standalone layer containing the whole image instead of a succession of incremental layers. Making a full image can be useful for performance reasons once the number of layers gets too large.

Warning

It is recommended to have the qemu-guest-agent package installed in the guest (see next section).

Note

In previous releases, pcocc images were saved in standalone directories. While this style of images is still properly handled by pcocc save, it is now considered deprecated and support will be removed in a future version.

Recommendations¶

Saving a running VM may lead to corruption if the filesystem is being accessed. To ensure a consistent filesystem image, pcocc tries to contact the Qemu guest agent in the VM to freeze the filesystems before creating a new image from this disk. Therefore, it is recommended to make sure that the qemu guest agent is running in the guest (see : pcocc-newvm-tutorial(7)).

If pcocc cannot contact the agent, it will emit a warning message but it will try to save the VM anyway. If installing the agent is not possible, you should freeze the filesystems by hand or simply shutdown your VM before calling pcocc save. In a Linux guest, you can use, as root shutdown -H now to shutdown a VM without powering it off (as you want to keep your resource allocation).

Options¶

-j, --jobid INTEGER

Jobid of the selected cluster

-J, --jobname TEXT

Job name of the selected cluster

-d, --dest URI

Make a full copy in a new directory

-s, --safe

Wait indefinitely for the Qemu agent to freeze filesystems

--full

Save a full image even if not necessary

-h, --help

Show this message and exit.

Examples¶

In these examples, we consider that the qemu-guest-agent is installed.

Create a new image revision¶

If you have write permissions on the image directory used by your VMs, you can create new image revisions. For example to create a new revision of the image used by first VM of your virtual cluster use:

$ pcocc save vm0
Saving image...
vm0 frozen
vm0 thawed
vm0 disk successfully saved to centos7-cloud revision 1

A new image revision is created

$ pcocc image show centos7-cloud
[..]

REVISION    SIZE       CREATION DATE
--------    ----       -------- ----
0           958  MB    2018-08-03 16:04:12
1           44.0 MB    2018-08-03 16:09:54

The next VM instantiated with this image will use the new revision. You can undo saves by removing the latest revisions (see pcocc-image(1)) or specify a specific revision in your template image URI.

Create a new independent images¶

If you want to create a new image or do not have write permissions on the image repository used by your VM you can use the -d flag to save to a new VM image:

$ pcocc save vm0 -d user:mycentos7
Saving image...
vm0 frozen
vm0 thawed
Merging snapshot with backing file to make it standalone...
vm0 disk successfully saved to user:mycentos revision 1

You can now create a template inheriting from the original one, but using the new image, by editing your templates.yaml file:

mycentos:
    inherits: centos7
    image: user:mycentos