From b3e3813ec2feb75167c4d56ef9580d70c7e3255e Mon Sep 17 00:00:00 2001
From: Agata Murawska <agatamurawska@google.com>
Date: Thu, 21 Jul 2011 17:31:44 +0200
Subject: [PATCH] Initial design doc for OVF support
Signed-off-by: Agata Murawska <agatamurawska@google.com>
[iustin@google.com: fixed formatting issues]
Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>
---
doc/design-draft.rst | 1 +
doc/design-ovf-support.rst | 166 +++++++++++++++++++++++++++++++++++++
2 files changed, 167 insertions(+)
create mode 100644 doc/design-ovf-support.rst
diff --git a/doc/design-draft.rst b/doc/design-draft.rst
index 390684b58..79468d047 100644
--- a/doc/design-draft.rst
+++ b/doc/design-draft.rst
@@ -12,6 +12,7 @@ Design document drafts
design-multi-reloc.rst
design-cpu-pinning.rst
design-chained-jobs.rst
+ design-ovf-support.rst
.. vim: set textwidth=72 :
.. Local Variables:
diff --git a/doc/design-ovf-support.rst b/doc/design-ovf-support.rst
new file mode 100644
index 000000000..d238259a7
--- /dev/null
+++ b/doc/design-ovf-support.rst
@@ -0,0 +1,166 @@
+==============================================================
+Ganeti Instance Import/Export using Open Virtualization Format
+==============================================================
+
+Background
+==========
+
+Open Virtualization Format is an open standard for packaging
+information regarding virtual machines. It is used, among other, by
+VMWare, VirtualBox and XenServer. OVF allows users to migrate between
+virtualization software without the need of reconfiguring hardware,
+network or operating system.
+
+Currently, exporting instance in Ganeti results with a configuration
+file that is readable only for Ganeti. It disallows the users to
+change the platform they use without loosing all the machine's
+configuration. Import function in Ganeti is also currently limited to
+the previously prepared instances.
+
+Implementation of OVF support allows users to migrate to Ganeti from
+other platforms, thus potentially increasing the usage. It also
+enables virtual machine end-users to create their own machines
+(e.g. in VirtualBox or SUSE Studio) and then add them to Ganeti
+cluster, thus providing better personalization.
+
+Overview
+========
+
+Open Virtualization Format description
+--------------------------------------
+
+According to the DMTF document introducing the standard: "The Open
+Virtualization Format (OVF) Specification describes an open, secure,
+portable, efficient and extensible format for the packaging and
+distribution of software to be run in virtual machines." OVF supports
+both single and multiple- configurations of VMs in one package, is
+host- and virtualization platform-independent and optimized for
+distribution (e.g. by allowing usage of public key infrastructure and
+providing tools for management of basic software licensing).
+
+There are no limitations regarding hard drive images used, as long as
+the description is provided. Any hardware described in a proper
+i.e. CIM - Common Information Model) format is accepted, although
+there is no guarantee that every virtualization software will support
+all types of hardware.
+
+OVF package should contain one file with .ovf extension, which is an
+XML file specifying the following (per virtual machine):
+
+- virtual disks
+- network description
+- list of virtual hardware
+- operating system, if any
+
+Each of the elements in .ovf file may, if desired, contain a
+human-readable description to every piece of information given.
+
+Additionally, the package may have some disk image files and other
+additional resources (e.g. ISO images).
+
+Supported disk formats
+----------------------
+
+Although OVF is claimed to support 'any disk format', what we are
+interested in is which of the formats are supported by VM managers
+that currently use OVF.
+
+- VMWare: ``.vmdk`` (which comes in at least 3 different flavours:
+ ``sparse``, ``compressed`` and ``streamOptimized``)
+- VirtualBox: ``.vdi`` (VirtualBox's format), ``.vmdk``, ``.vhd``
+ (Microsoft and XenServer); export disk format is always ``.vmdk``
+- XenServer: ``.vmdk``, ``.vhd``; export disk format is always
+ ``.vhd``
+- Red Hat Enterprise Virtualization: ``.raw`` (raw disk format),
+ ``.cow`` (qemu's ``QCOW2``)
+- other: AbiCloud, OpenNode Cloud, SUSE Studio, Morfeo Claudia,
+ OpenStack
+
+In our implementation of the OVF we plan to allow a choice between
+raw, cow and vmdk disk formats for both import and export. The
+justification is the following:
+
+- Raw format is supported as it is the main format of disk images used
+ in Ganeti, thus it is effortless to provide support for this format
+- Cow is used in Qemu, [TODO: ..why do we support it, again? That is,
+ if we do?]
+- Vmdk is most commonly supported in virtualization software, it also
+ has the advantage of producing relatively small disk images, which
+ is extremely important advantage when moving instances.
+
+The conversion between RAW and the other formats will be done using
+qemu-img, which transforms, among other, raw disk images to monolithic
+sparse vmdk images.
+
+
+Planned limitations
+===================
+
+The limitations regarding import of the OVF instances generated
+outside Ganeti will be (in general) the same, as limitations for
+Ganeti itself. The desired behavior in case of encountering
+unsupported element will be to ignore this element's tag and inform
+the user on console output, if possible - without interruption of the
+import process.
+
+Package
+-------
+
+There are no limitations regarding support for multiple files in
+package or packing the ovf package into one OVA (Open Virtual
+Appliance) file. As for certificates and licenses in the package,
+their support will be under discussion after completion of the basic
+features implementation.
+
+Multiple Virtual Systems
+------------------------
+
+At first only singular instances (i.e. VirtualSystem, not
+VirtualSystemCollection) will be supported. In the future multi-tiered
+appliances containing whole nodes (or even clusters) are considered an
+option.
+
+Disks
+-----
+
+As mentioned, Ganeti will allow exporting only ``raw``, ``cow`` and
+``vmdk`` formats. As for import, we will support all that
+``qemu-img`` can convert to raw format. At this point this means
+``raw``, ``cow``, ``qcow``, ``qcow2``, ``vmdk`` and ``cloop``. We do
+not plan for now to support ``vdi`` or ``vhd``.
+
+We support compression both for import and export - for export this
+will use ovftools with chosen level of compression. There is also a
+possibility to provide virtual disk in chunks of equal size.
+
+When no ``ovf:format`` tag is provided during import, we assume that
+the disk is to be created on import and proceed accordingly.
+
+Network
+-------
+
+There are no known limitations regarding network support.
+
+Hardware
+--------
+
+TODO
+
+Operating Systems
+-----------------
+
+TODO
+
+Other
+-----
+
+Implementation details
+======================
+
+TODO
+
+.. vim: set textwidth=72 :
+.. Local Variables:
+.. mode: rst
+.. fill-column: 72
+.. End:
--
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