Best virtual disk format? VMDX, OVF, RAW, BIN, VDI, QEMM???

[hanasaki]

Now that VBox can natively use VMWare images as well as its own; what are your thoughts on which is better for what types a functionality? in terms of host diskspace used, performance, reliability, etc... resize/shrink/expand...

For Sun, what is the future of the VDI format? Will there be future support for the open Virtualization Format OVF?

[TerryE]

VDI is the "home" format for VBox, but with 2.1 the product is moving to a format neutral approach supporting VHD and VMDKs. This is pretty new functionality. The major bugs were fixed with 2.1.2 but think a few small gremlins remain, though I suspect that these will quickly be ironed out over the next few dot releases. I suspect that there will be little performance difference between the formats, though we have benchmarked VDIs vs raw VMDKs (native partitions) and in fact the VDI performance is about 5-10% better in the tests.

So I just stick with VDIs

[hanasaki]

VMDK support is great. The possibility of sharing a virtual disk as-is between vmware and vbox (well except for the guest additions) is quite nice.

I had thought VMDK was vmware specific? And now (mostly on their site) you can find OVF (vmware pushing a new format? that is "open"?)

http://www.vmware.com/appliances/learn/ovf.html

With any luck there will be converters between them. For now I may go with using my vmware workstation to produce linux vmdk's since there do not seem to be VDI to VMDK converters and thus VMDK is the common denominator.

[TerryE]

Just picking up the relevant section (5.2 Virtual Disk Formats) of the DMTF OVF Specification V1.0.0 (preliminary standard)

• OVF does not require any specific disk format to be used, but to comply with this specification the disk format shall be given by a URI which identifies an unencumbered specification on how to interpret the disk format. The specification need not be machine readable, but it shall be static and unique so that the URI may be used as a key by software reading an OVF package to uniquely determine the format of the disk. The specification shall provide sufficient information so that a skilled person can properly interpret the disk format for both reading and writing of disk data. It is recommended that these URIs are resolvable.

I applaud the OVF concept and like the goals of having vendor neutral VM encapsulations, but what OVF current lays out is an encapsulation model and a common set of DTDs for describing a VM.

Like a lot of standards this one seems to be a long way from being a true standard, and too many vendors have too vested interests in maintaining product differentiation rather than product interoperability.

[hanasaki]

now that 2.2 has support for OVF
http://vbox.innotek.de/pipermail/vbox-a ... 00013.html

what would the recommended format be for what scenarios?

Does vbox support all the virtual disk shrink, expand etc... for all of the supported formats of VDI, VMDX and OVF?

[TerryE]

AFAIK, from the comments in the source code, the intent is to offer equal support for all formats. They're not quite there yet. Even so, there is still the issue that other vendors, such as VMware, can unilaterally change / enhance there formats so you will get time windows where VirtualBox supports version N VMDKs, but not yet version N+1.

[Phobos]

From my POV, my suggestions would be:

- If you are planning to migrate a lot of VMs from one server to other, or are planning to distribute your VM, use OVF
- If you have a mixed VBox - VMware environment or also if you want to share your machine only between those two environments, use VMDK
- If you have a mixed VBox - Hyper-V/Virtual PC environment or also if you want to share your machine only between those two environments, use VHD
- Else, stick with VDI for the moment (best performance/support)

[hanasaki]

What tools are there... and will there be for converting between formats? Is there a matrix of CONVERT FROM -> CONVERT TO and commands to do so?

[Phobos]

What tools are there... and will there be for converting between formats? Is there a matrix of CONVERT FROM -> CONVERT TO and commands to do so?

http://www.unix-tutorials.com/go.php?id=4011
http://www.benfrain.com/notepad/2009/03 ... re-to.html ...

google is not that hard to use...

you won't need changing between formats too much anyways...