[occi-wg] Opinion Poll: IaaS or PaaS ?

[Randy Bias]

Wes,


	Unfortunately, we're very far from this.  There are three different  
types of hypervisor: software (VMware), hardware (Xen, et al), and  
paravirtualized (VMware + VMI, Xen in paravirt mode, etc.).

	Despite the fact that folks claim that unmodified VMs can run under  
Xen, in the real world *everyone* provides customized network and disk  
drivers for the guest OS because the performance is abysmal.  These  
are 'paravirtualized drivers', which is why the performance can be so  
dramatically affected.  Unfortunately, there isn't a standard of any  
kind, so you'll find that the paravirt drivers for disk drives for the  
SLES Xen hypervisor will have problems running under the RHEL Xen  
hypervisor and vice versa.

	The same kind of issue holds true for VMware where you just won't see  
acceptable performance unless the VMware drivers and tools are  
installed.

	Now, you could say: "Well, folks will just have a performance hit"  
and I would agree if we were talking about inside the firewall, but  
the reality is that in public clouds folks are very eager to get the  
maximum performance from a single instance in order to maximize their  
dollars spent.

	So you are quickly in a situation where ignoring the OS isn't  
feasible.  Even though OVF doesn't provide for this, it SHOULD.  It's  
an oversight on the part of VMware and Xen.  Once providers start  
allowing uploading of arbitrary VM images, they are also going to need  
what OS is in the image package so that they can dynamically install  
the correct paravirt drivers for the hypervisor they are using.

	If you don't have this capability then allowing the upload of  
completely opaque images and hoping they will have any kind of  
reasonable performance on an arbitrary cloud providers system is a  
pipe dream.  This is an area badly in need of standardization, but I  
doubt it will come any time soon.


--Randy


On Jun 14, 2009, at 1:44 PM, Wes Felter wrote:

> On Jun 14, 2009, at 6:35 AM, Gary Mazz wrote:
>
>> Sam Johnston's timely IaaS feature matrix brings up some interesting
>> issues, one in particular, what are the specific features that can be
>> included in an IaaS.
>>
>> Many of the IaaS provider are also providing one or more operating
>> systems while other are providing closer to bare metal. Is the OS  
>> part
>> of the Infrastructure or  part of the Platform ?
>
> IMO IaaS is about flexibility and thus should provide bare metal (or
> virtual bare metal) so that customers can use any OS they choose. OVF
> seems to require this, since an OVF image can contain any OS; thus if
> your IaaS claims to support OVF then you should be able to run *any*
> OVF image containing *any* OS. I think this also requires full
> virtualization since paravirtualization is neither standardized nor
> widespread.
>
> IaaS providers can provide optional prebuilt OS images, but it
> shouldn't be part of the infrastructure.
>
> Wes Felter - wesley at felter.org - http://felter.org/wesley/
>
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Randy Bias, Cloud Strategist
+1 (415) 939-8507 [m], randyb at neotactics.com
BLOG: http://cloudscaling.com

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