Synnefo » snf-ganeti

=============

OVF converter

=============

Using ``ovfconverter`` from the ``tools`` directory, one can easily

convert previously exported Ganeti instance into OVF package, supported

by VMWare, VirtualBox and some other virtualization software. It is

also possible to use instance exported from such a tool and convert it

to Ganeti config file, used by ``gnt-backup import`` command.

For the internal design of the converter and more detailed description,

including listing of available command line options, please refer to

:doc:`design-ovf-support`

As the amount of Ganeti-specific details, that need to be provided in

order to import an external instance, is rather large, we will present

here some examples of importing instances from different sources.

It is also worth noting that there are some limitations regarding

support for different hardware.

Limitations on import

=====================

Network

-------

Available modes for the network include ``bridged`` and ``routed``.

There is no ``NIC`` mode, which is typically used e.g. by VirtualBox.

For most usecases this should not be of any effect, since if

``NetworkSection`` contains any networks which are not discovered as

``bridged`` or ``routed``, the network mode is assigned automatically,

using Ganeti's cluster defaults.

Backend

-------

The only values that are taken into account regarding Virtual Hardware

(described in ``VirtualHardwareSection`` of the ``.ovf`` file) are:

- number of virtual CPUs

- RAM memory

- hard disks

- networks

Neither USB nor CD-ROM drive are used in Ganeti. We decided to simply

ignore unused elements of this section, so their presence won't raise

any warnings.

Operating System

----------------

List of operating systems available on a cluster is viewable using

``gnt-os list`` command. When importing from external source, providing

OS type in a command line (``--os-type=...``) is **required**. This is

because even if the type is given in OVF description, it is not detailed

enough for Ganeti to know which os-specific scripts to use.

Please note, that instance containing disks may only be imported using

OS script that supports raw disk images.

References

----------

Files listed in ``ovf:References`` section cannot be hyperlinks.

Limitations on export

=====================

Disk content

------------

Most Ganeti instances do not contain grub. This results in some

problems when importing to virtualization software that does expect it.

Examples of such software include VirtualBox and VMWare.

To avoid trouble, please install grub inside the instance before

exporting it.

Import to VirtualBox

--------------------

``format`` option should be set to ``vmdk`` in order for instance to be

importable by VirtualBox.

Tests using existing versions of VirtualBox (3.16) suggest, that

VirtualBox does not support disk compression or OVA packaging. In future

versions this might change.

Import to VMWare

----------------

Importing Ganeti instance to VMWare was tested using ``ovftool``.

``format`` option should be set to ``vmdk`` in order for instance to be

importable by VMWare.

Presence of Ganeti section does seem to cause some problems and

therefore it is recommended to use ``--external`` option on export.

Import of compressed disks generated by ovfconverter was impossible in

current version of ``ovftool`` (2.1.0). This seems to be related to old

``vmdk`` version. Since the conversion to ``vmdk`` format is done using

``qemu-img``, it is possible and in fact expected, that future versions

of the latter tool will resolve this problem.

Import examples

===============

Ganeti's OVF

------------

If you are importing instance created using ``ovfconverter export`` --

you most probably will not have to provide any additional information.

In that case, the following is all you need (unless you wish to change

some configuration options)::

	ovfconverter import ganeti.ovf

	[...]

	gnt-instance import -n <node> <instance name>

Virtualbox, VMWare and other external sources

---------------------------------------------

In case of importing from external source, you will most likely have to

provide the following details:

- ``os-type`` can be any operating system listed on ``gnt-os list``

- ``name`` that has to be resolvable, as it will be used as instance

  name (even if your external instance has a name, it most probably is

  not resolvable to an IP address)

These are not the only options, but the recommended ones. For the

complete list of available options please refer to

`Command Line description <design-ovf-support.rst>`

Minimalistic but complete example of importing Virtualbox's OVF

instance may look like::

    ovfconverter virtualbox.ovf --os-type=lenny-image \

      --name=xen.test.i1 --disk-template=diskless

    [...]

    gnt-instance import -n node1.xen xen.test.i1

Export example

==============

Exporting instance into ``.ovf`` format is pretty streightforward and

requires little - if any - explanation. The only compulsory detail is

the required disk format, provided using the ``--format`` option.

Export to another Ganeti instance

---------------------------------

If for some reason it is convenient for you to use ``ovfconverter`` to

move instance between clusters (e.g. because of the disk compression),

the complete example of export may look like this::

    gnt-backup export -n node1.xen xen.test.i1

    [...]

    ovfconverter export --format=vmdk --ova \

      /srv/ganeti/export/xen.i1.node1.xen/config.ini

    [...]

The result is then in

``/srv/ganeti/export/xen.i1.node1.xen/xen.test.i1.ova``

Export to Virtualbox/VMWare/other external tool

-----------------------------------------------

Typically, when exporting to external tool we do not want

Ganeti-specific configuration to be saved. In that case, simply use the

``--external`` option::

    gnt-backup export -n node1.xen xen.test.i1

    [...]

    ovfconverter export --external --output-dir ~/ganeti-instance/ \

      /srv/ganeti/export/xen.i1.node1.xen/config.ini

Known issues

============

Conversion errors

-----------------

If you are encountering trouble when converting the disk, please ensure

that you have newest ``qemu-img`` version.

OVA and compression

-------------------

The compressed disks and OVA packaging do not work correctly in either

VirtualBox (old version) or VMWare.

VirtualBox (3.16 OSE) does not seem to support those two, so there is

very little we can do about this.

As for VMWare, the reason behind it not accepting compressed or packed

instances created by ovfconverter seems to be related to the old vmdk

version.

Problems on newest VirtualBox

-----------------------------

In Oracle VM Virtualbox 4.0+ there seems to be a problem when importing

any OVF instance created by ovfconverter. Reasons are again unknown,

this will be investigated.

Disk space

----------

The disk space requirements for both import and export are at the moment

very large - we require free space up to about 3-4 times the size of

disks. This will most likely be changed in future versions.

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