[libvirt] [PATCH v3 4/7] qemu: Translate the iscsi pool/volume disk source

[Daniel P. Berrange]

On Tue, Jul 23, 2013 at 03:29:40PM +0200, Paolo Bonzini wrote:
> Il 23/07/2013 15:26, Daniel P. Berrange ha scritto:
> >> > 
> >> > Ok, this answers my question. :)
> >> > 
> >> > I think the default mode should be direct, because otherwise things such
> >> > as persistent reservations do not work.
> > No, the default has to be host mode, because that is the only mode that
> > is guaranteed to be usable with any QEMU. The direct mode requires a
> > QEMU that is new enough, and a distro to have enabled it. We can't
> > rely on that as a default choice.
> 
> Volume sources are also new enough that you can assume a good QEMU.

No we can't assume that. New libvirt is frequently used with old QEMU
and we want to have good default behaviour there.

> Host mode for iSCSI is broken.  It also doesn't reconnect well if you
> have a network problem, because after a LUN rescan the inode may change.

That's a much smaller level of brokeness, than if QEMU doesn't support
the iscsi block protocol & thus the default configuration won't even
boot.

Daniel
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