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

Paolo Bonzini pbonzini at redhat.com
Wed Jul 24 10:37:10 UTC 2013


Il 24/07/2013 12:31, Daniel P. Berrange ha scritto:
> On Wed, Jul 24, 2013 at 12:25:17PM +0200, Paolo Bonzini wrote:
>> Il 24/07/2013 11:54, Daniel P. Berrange ha scritto:
>>>> but anyway, we provide good enough documentations, so if one wants to
>>>> use "direct" mode, he can still change the xml to use it, any big problems
>>>> here? though defaulting to "direct" is more convenient for these users.
>>>
>>> Defaulting to "direct" is *NOT* more convenient for all users, only
>>> those who happen to have a new enough QEMU, from a vendor who actually
>>> decided to compile in the iSCSI support. If they're lacking such a QEMU
>>> then the "direct" mode will prevent the default config from even starting.
>>> This can never be an acceptable default choice. mode="host", while it huas
>>> some limitations in features, is the only option that is capable of working
>>> with any QEMU
>>
>> s/limitations in features/possibility of wreaking havoc to clusters/
> 
> This isn't a new issue. People have been using KVM with iSCSI in host
> mode for as long as KVM has existed and the sky hasn't fallen in
> clusters. As long as it is a documented limitation, that admins can
> address with a config setting if desired, I don't see that this is
> suddenly something we must fix at the cost of breaking the default
> config for QEMU's without iSCSI support.

Understood, that's why I suggested not having a default config at all
for type='lun' devices.

Also, can libvirt at least detect using a volume on a pool that wasn't
started, and fail unless mode='direct'?

Paolo




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