Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1)

[Stefan Hajnoczi <stefanha@gmail.com>]

On Thu, Nov 22, 2012 at 6:46 PM, Dietmar Maurer <dietmar@proxmox.com> wrote:
>> > Did you look at the VMDK "Stream-Optimized Compressed" subformat?
>>
>> We've gone down several sub-threads discussing whether VMDK is suitable.
>> I want to summarize why this is a good approach:
>>
>> The VMDK format already allows for out-of-order data and is supported by
>> existing tools - this is very important for backups where people are
>> (rightfully) paranoid about putting their backups in an obscure format.  They
>> want to be able to access their data years later, whether your tool is still
>> around or not.
>
> The VMDK format has strong disadvantages:
>
> - unclear License (the spec links to patents)

I've already pointed out that you're taking an inconsistent position
on this point.  It's FUD.

> - they use a very slow compression algorithm (deflate), which makes it unusable for backup

I've already pointed out that we can optionally support other algorithms.

Stefan