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Re: [Xen-API] VDI import/export with deltas


I'm happy to see a prototype for import/export. It seems that this discussion 
is generating a lot of traffic - do we plan to have some sort of design session 
about it? I believe the storage team and the stackers would love to be involved 
in these sessions.
We also had a discussion which might be releated:

I think the idea of a filesystem interface is very good, however given that the 
filesystem must provide a consistent view and transactions, as other processes 
might manipulate files (GC), I think for the moment, let's try to do a bit 
narrower interface.

I also wanted to raise the content ID question - would be nice to generate a 
content id during the export, and mark it as dirty whenever it has changed, so 
that the client would know that she should not expect a consistent output.


-----Original Message-----
From: Dave Scott 
Sent: Thursday, August 28, 2014 5:10 PM
To: Bob Ball
Cc: xen-api@xxxxxxxxxxxxxxxxxxxx; Mate Lakat; John Garbutt; Ant Messerli
Subject: Re: VDI import/export with deltas

On 28 Aug 2014, at 15:50, Bob Ball <bob.ball@xxxxxxxxxx> wrote:

>> http://wiki.xensource.com/wiki/Disk_import/export_APIs
> This is great, but I think we're missing the ability to pull a VHD in or push 
> a VHD out.
> The OpenStack case needs to call a vm-import giving a URL to pull a VHD from, 
> and a vm-export to push a VHD out to.
> In particular I think we need to set specific headers as well, as 
> authentication, so I'd like to propose the following as a hopefully simple 
> extension:
> xe vdi-export uuid=$VDI format=vhd dest= 
> headers:arbitrary_string=$AUTH_TOKEN
> xe vdi-import uuid=$RESTORE format=vhd 
> source= 
> headers:arbitrary_string=$AUTH_TOKEN

This looks sensible to me; plus I'd like to use URLs more in the storage 
interface in future.

> OpenStack also has a case for using bittorrent to download the VDI from peers 
> rather than the central server, but I don't see how to accomplish that with 
> the current proposal without requiring double the disk space as we'd need to 
> download it then push it into XS.

So at the moment, do you receive the .vhd data by bittorrent in-place?

When I last spoke to John about this we discussed some kind of import/export 
plugin extension. I guess to do the most efficient thing possible it would have 
to have access to (at least a subset of) the physical storage, so it can 'drop 
in' a vhd (or qcow or vmdk). Ideally the plugin wouldn't see anything else (so 
it couldn't get confused or make a mistake) and the modified files would be 
health-checked when the operation is finished.

> Thoughts?

Maybe we could make a safe import/export virtual filesystem with FUSE? Perhaps 
you could even SMB export a virtual folder for XenCenter users on windows to 
drag 'n drop files into.


> Thanks,
> Bob
>> There's still time before 2.0 to change how these work, so your 
>> comments and criticism would be appreciated.
>> Thanks!
>> Dave
>> [1] https://github.com/xapi-project/xapi-project/issues/1
>> [2] https://github.com/xapi-project/xen-api/issues/1778
>> [3] https://github.com/xapi-project/vhd-tool/pull/14
>> _______________________________________________
>> Xen-api mailing list
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