UCS 2.4 - Univention

6.3.2.2 Operations (Starting/stopping/suspending virtual machines)
6.3 Managing virtual machines with UVMM
Instances created via UVMM are turned off in the initial status. This status can changed in the overview
of the respective virtualisation server in the respective list entry or in the overview of the virtual machine
itself. In the latter case, there is an Operations section, in which the status can be set. The following
possibilities exist:
Start starts the virtual machine.
Stop turns the virtual machine off. It must be noted that the operating system is not shutdown first, i.e., it
should be compared with turning off a computer by pulling the power plug.
Pause assigns the instance no further CPU time. This still uses the working memory on the virtualisation
server, but the instance itself is paused.
Suspend saves the contents of the machine’s system memory on the hard drive and does not assign the
machine further CPU time, i.e., compared with Pause the working memory is also freed. Suspended
machines can be restarted with Start. This function is only available on KVM-based virtualisation
servers.
Resume starts assigning the instance CPU time again, so that it continues in the state it was prior to the
pausing.
Remove Virtual instances no longer required can be deleted along with all their hard drives and ISO
images. The images to be deleted can be selected from a list. It must be noted that ISO images and
sometimes also hard drive images may still be used by other instances. They should only be deleted
when they are no longer used by any instance.
A further function which can be found in the Operations section of the overview is the possibility of migrat-
ing a virtual machine to another virtualisation server. This works with both paused and running instances
(live migration). The option is only displayed if at least two compatible virtualisation servers are available
in the domain.
During the migration it must be noted that the images of the mounted hard drives and CDROM drive must
be accesible by both virtualisation servers. This can be achieved, for example, by storing the images in a
central storage system. Notes on the setting up of this type of environment can be found under [14].
6.3.2.3 Drives (Hard drives/CD-ROM/DVD-ROM/floppy)
The Drives section contains a list of the defined drives with the type, image file and size as well as the
assigned storage pool. At the end of each line there is a Delete button, which can be used to remove the
drive (the image file can also optionally be deleted with it). In addition, a wizard can be used to create new
hard drives and CDROM drives.
Adding a drive If virtual hard drives are added, image files are usually used for the data keeping. An
image file can either be generated for this purpose or an existing image file can be assigned to a virtual
machine. Alternatively, a hard drive partition can also be assigned to a virtual machine via the Use a local
device option.
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