Robert,
OK, I agree that we can't neglect transition, but as David Black points out,
it's probably the right thing to sweep certain "traditional" storage
transports. namely FCoE (for now, if not indefinitely), under the rug for a
number of reasons.
Likewise we also need to evolve technologies in the "traditional" network that
will bridge gaps that pure hypervisor-based overlays will not satisfy (for one
reason or other) for some time.
Best -- aldrin
On Aug 27, 2012, at 3:54 AM, Robert Raszuk wrote:
> Aldrin,
>
> What I primarily had in mind was "object storage" like S3, Rackspace cloud
> Files, Swift etc ...
>
> So one can say this is all IP so VM will just be able to access it - done. If
> everyone in this WG agrees with it is great.
>
> However perhaps if VM is using storage over IP during migration we need to
> special handle it ... propose fast-connectivity-restoration techniques on the
> storage PE side as mandatory to reduce the switchover time ? Maybe recommend
> right sequence of events ?
>
> Thx,
> R.
>
>
>> Neither is overlay networking new. But that's not my point.
>>
>> Ceph is merely an example I use to make the point that VMs accessing
>> storage servers over a virtual network is not IMO compatible with
>> arguments for a non-traditional cloud.
>>
>> Feel free to provide other real world examples of real cloud storage
>> other than Ceph. Would love to see what's on your list.
>>
>> Best. -- aldrin
>>
>> On Sunday, August 26, 2012, wrote:
>>
>> That is the case anytime a hypervisor provides a VM with a "local"
>> block device which is backed by network based storage ("VM itself
>> does not need to connect to network storage"). This is not something
>> new or unique provided by so called "cloud storage" such as Ceph.
>>
>> Cheers,
>>
>> Brad
>>
>>
>>
>> -----Original Message-----
>> *From: *Aldrin Isaac [[email protected]]
>> *Sent: *Sunday, August 26, 2012 07:45 PM Central Standard Time
>> *To: *Black, David
>> *Cc: *[email protected]; [email protected]
>> *Subject: *Re: [nvo3] Storage (part of: Let's refocus on real world)
>>
>> AFAIK, scale out cloud storage software such as Ceph do not rely on
>> FC, FCoE, NFS or iSCSI on the VM. Ceph storage appears to the VM as
>> local storage and does not depend on network virtualization. VM
>> migration is not an issue for Ceph since the VM itself does not need
>> to connect to a storage server over the network. So as far as real
>> cloud storage is concerned nothing is being swept under the rug.
>>
>> -- aldrin
>>
>> On Sunday, August 26, 2012, Black, David wrote:
>>
>> Robert,
>>
>> > Also as you have pointed out storage discussion can not be
>> just swapped
>> > under carpet and addressed by quote: "storage issues are out
>> of the scope".
>>
>> I agree ... and that looks like my cue to say something ...
>> e.g., see the
>> domain part of my email address ;-).
>>
>> iSCSI and NFS use TCP/IP in the storage stack and hence will run
>> fine over
>> all of the data encapsulations being discussed here. If the
>> iSCSI initiator
>> or NFS client is in the VM, that's most of the discussion.
>> That's not always
>> the case for a number of reasons - the obvious one is that a
>> hypervisor
>> iSCSI initiator or NFS client is required if the VM's executable
>> image is being
>> loaded and/or paged using one of those protocols. It's also the
>> case that
>> many hypervisors simplify the storage interface presented to VMs
>> so that it
>> looks like direct attached or internal disk drives), and map
>> those disks to
>> networked storage using a hypervisor iSCSI initiator or NFS
>> client. Ensuring
>> that the VM migration destination hypervisor has appropriate
>> connectivity to
>> storage is mostly a configuration concern. The upshot is that
>> iSCSI and NFS
>> run fine over nvo3-encapsulated networks.
>>
>> In contrast, as I said at the microphone at the nvo3 BOF in
>> Paris, I suggest
>> that the WG not initially consider FCoE, in order to defer
>> spending time on
>> discussing how to deliver DCB Ethernet service/behavior
>> (required by FCoE -
>> ordinary non-DCB Ethernet isn't sufficient for FCoE because FCoE
>> is *very*
>> sensitive to drops) through the encapsulation(s).
>>
>> Thanks,
>> --David
>>
>>
>> > -----Original Message-----
>> > From: [email protected] [mailto:[email protected]] On
>> Behalf Of Robert
>> > Raszuk
>> > Sent: Saturday, August 25, 2012 11:55 AM
>> > To: Ivan Pepelnjak
>> > Cc: Black, David; [email protected]; Linda Dunbar
>> > Subject: Re: [nvo3] Let's refocus on real world
>> >
>> > Ivan,
>> >
>> > > ... or I may be completely wrong.
>> >
>> > I think you are actually right on the spot correct.
>> >
>> > However I am afraid authors of this document are not likely
>> to admit
>> > that TOR switches should be just basic IP nodes providing
>> only transport
>> > between servers.
>> >
>> > Likewise they will not likely to admit that all logic of
>> encapsulation
>> > should happen on the hyper-visors as they are simply not in that
>> > technology space.
>> >
>> > Similarly I very much agree and support providing clear
>> distinction
>> > between "cold" and "hot" VM mobility cases and perhaps even
>> further
>> > provide number of sub-classes hot VM mobility can be
>> accomplish today -
>> > clearly there is more then one way.
>> >
>> > Also as you have pointed out storage discussion can not be
>> just swapped
>> > under carpet and addressed by quote: "storage issues are out
>> of the scope".
>> >
>> > While Linda was perhaps right to say that today most storage
>> today is
>> > coming to servers via backend this is what I would call very
>> inefficient
>> > and legacy way. If we are to think ahead one needs to observe
>> how the
>> > industry advances in storage virtualization via front-end IP
>> very often
>> > not co-located with the compute racks.
>> >
>> > In my view network related mobility discussion is not about
>> TOR or about
>> > VLANs. It is about an IP layer above IP transport which would
>> carry all
>> > necessary information of the actual location of the VMs and
>> which in
>> > fact would play the main role in shortening or eliminating the
>> > triangular routing problem.
>> >
>> > Rgs,
>> > R.
>> >
>> >
>> >
>>
>>
>>
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