[libvirt] [PATCH v2 2/7] conf: Introduce new XML tag "mode" for disk source

[Osier Yang]

On 19/07/13 00:09, Daniel P. Berrange wrote:
> On Thu, Jul 18, 2013 at 11:02:37AM -0400, John Ferlan wrote:
>> From: Osier Yang <jyang at redhat.com>
>>
>> There are two ways to use a iSCSI LUN as disk source for qemu.
>>
>> * The LUN's path as it shows up on host, e.g.
>>    /dev/disk/by-path/ip-$ip:3260-iscsi-$iqn-fc18:iscsi.iscsi0-lun-1
>>
>> * The libiscsi URI, e.g.
>>    iscsi://demo.org:6000/iqn.1992-01.com.example/1
>>
>> For a "volume" type disk, if the specified "pool" is of iscsi
>> type, we should support to use the LUN in either of above 2 ways.
>> That's why to introduce a new XML tag "mode" for the disk source
>> (libvirt should support iscsi pool with libiscsi, but it's another
>> new feature, which should be done later).
>>
>> The "mode" can be either of "host" or "uri". Use "host" to indicate
>> use of the LUN with the path as it shows up on host. Use "uri" to
>> indicate to use it with the libiscsi URI (future patches may support
>> to use network type libvirt storage too, e.g. Ceph, that's why to use
>> a more general name "uri").
> I'm thinking that the mode is really describing the way in which
> QEMU uses the iSCSI LUN. Either it access it via the host, or it
> accesses it directly.   The fact that the direct access mode has
> a cli arg encoded as an URI is really an implementation detail of
> current QEMU cli syntax.

yes.

>
> So I'd suggest the "mode" accept either "host" or "direct" instead
> of "host" or "uri".

agreed. i was not that sure about the name "uri" when making the
patches actually, "direct" sounds better to me.

>
>
> Daniel