At VMworld 2012 in San Francisco VMware announced a vMotion enhancement.

VMware describes it like this;

“vSphere 5.1 now enables users to combine “vMotion” and “Storage vMotion” into one operation. The combined migration copies both the virtual machine memory and its disk over the network to the destination host.”

what they probably mean is a functional combination of the two because technically the “Storage VMotion” process works completely different (see below). I presume it is technically more a combination of VMotion and HBR (Host Based Replication).

Since HBR was only a feature of Site Recovery Manager (SRM) the guys at VMware decided to decouple the feature from SRM and released it as a standard available feature of every vSphere version, they call it “vSphere Replication” or in short “vR”.

Sometimes you have to give away some functionality to stay ahead of the competition. Mind you this is not just to support the VMotion without shared storage, “vSphere Replication” is going to have an impact. VMware releases “vR” in every vSphere license from Essentials Plus through Enterprise Plus, the target is definitely SMB and we all know who the competition is there. I will describe vSphere Replication in a different blog item, it definitely deserves it..

Now back to the vMotion enhancement, below a short description of the two existing functionalities

VMotion = Moving the CPU and RAM load of a running VM to another ESXi host, the process uses a dedicated vMotion network. The source and destination ESXi hosts need access to the same storage hosting the Disk files of the VM.

image6 sVMotion (Storage VMotion) = Moving the Disk files of a running VM to another storage location, the operation is done internally on a single ESXi server (or offloaded in-band to the storage array if the arrays supports hardware acceleration via VAAI). There is no communication done over the ‘network’ via the ESXi Service Console or management network for a Storage vMotion operation. The VM keeps running on the same ESXi host through the entire process.

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Both options need shared storage; the announced VMotion enhancement does not need that.

It is somewhat strange that they have not yet given this functionality its own name. I wonder what the real name is going to be, Microsoft calls it “Shared Nothing Live Migration” so it will probably not be “Shared Nothing VMotion”
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Paul Geerlings

Author Paul Geerlings

I am used to working in Enterprise IT environments since 1997, in technical as well as architect roles. It is my passion to implement new technologies and share my experience within a team. To me x86 virtualization is a synonym for VMware, i have been working with their products since 2004, there simply is no enterprise alternative. The VMware hypervisor was so disruptive back then, one can easily speak of two IT eras, one without and one with x86 virtualization using VMware technology. The next wave we are riding is Software Defined I am convinced this will proof to be almost as disruptive.

More posts by Paul Geerlings
30 August 2012

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