Re: [Qemu-devel] [RFC PATCH 0/2] GlusterFS support in QEMU - v2

[ronnie sahlberg]

Why not use

-drive file=gluster://server[:port]/volname/image

A great many protocols today use the form

<protocol>://<server>:<port>]/<path>

so this would make it consistent with a lot of other naming schemes
out there, and imho make
the url more intuitive.


FTP looks like this :   ftp://user:address@hidden:port/path
NFS looks like this :   nfs://<host>:<port><url-path>
CIFS looks like this :
smb://[[[authdomain;address@hidden:port][/share[/path][/name]]][?context]

For iSCSI we use  :   iscsi://<server>[:<port>]/<target>/<lun>


(The iscsi syntax was picked explicitely to be consistent with the
de-facto url naming scheme.)


I would argue that this is the de-facto way to create a url for
different protocols,   so it would imho be natural to specify a
glusterfs url in a similar format.


ronnie sahlberg


On Mon, Jul 23, 2012 at 7:16 PM, Daniel P. Berrange <address@hidden> wrote:
> On Sat, Jul 21, 2012 at 01:59:17PM +0530, Bharata B Rao wrote:
>> Hi,
>>
>> Here is the v2 patchset for supporting GlusterFS protocol from QEMU.
>>
>> This set of patches enables QEMU to boot VM images from gluster volumes.
>> This is achieved by adding gluster as a new block backend driver in QEMU.
>> Its already possible to boot from VM images on gluster volumes, but this
>> patchset provides the ability to boot VM images from gluster volumes by
>> by-passing the FUSE layer in gluster. In case the image is present on the
>> local system, it is possible to even bypass client and server translator and
>> hence the RPC overhead.
>>
>> The major change in this version is to not implement libglusterfs based
>> gluster backend within QEMU but instead use libgfapi. libgfapi library
>> from GlusterFS project provides APIs to access gluster volumes directly.
>> With the use of libgfapi, the specification of gluster backend from QEMU
>> matches more closely with the GlusterFS's way of specifying volumes. We now
>> specify the gluster backed image like this:
>>
>> -drive file=gluster:address@hidden:volname:image
>>
>> - Here 'gluster' is the protocol.
>> - 'address@hidden' specifies the server where the volume file specification 
>> for
>>   the given volume resides. 'port' is the port number on which gluster
>>   management daemon (glusterd) is listening. This is optional and if not
>>   specified, QEMU will send 0 which will make libgfapi to use the default
>>   port.
>> - 'volname' is the name of the gluster volume which contains the VM image.
>> - 'image' is the path to the actual VM image in the gluster volume.
>
> I don't think we should be using '@' as a field separator here, when ":"
> can do that job just fine. In addition we already have a precendent set
> with the sheepdog driver for using ':' for separating all fields:
>
>   -drive file=sheepdog:example.org:6000:imagename
>
> If you want to allow for port number to be omitted, this can be handled
> thus:
>
>   -drive file=sheepdog:example.org::imagename
>
> which is how -chardev deals with omitted port numbers
>
> Regards,
> Daniel
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