Scott Lowe's Blog

The way to really view VMware Virtual Datacenter OS (VDC-OS) is not as a “datacenter OS”, because it’s not intended to provide automation of non-virtual resources. Instead, look at VDC-OS as a framework. Within this framework are sets of services that can be extended or modified in very standardized ways (via APIs and SDKs) to provide different functionality for the applications running within that framework.

What VMware is working on is an OS for the virtual datacenter, not a virtual OS for the datacenter. The distinction is important. VDC-OS isn’t intended to be an OS for all aspects of the datacenter. It’s intended to be an OS for all aspects of the virtual datacenter.

When you think of an OS, you think of software that manages access to resources and provides services to applications. That’s what VMware is doing with VDC-OS: managing access to resources and providing services to applications, only this time the applications are workloads (virtual machines with an OS and a set of applications on that guest OS). VDC-OS will provide sets of services to these applications:

• Application vServices, like availability, security, and scalability. These application vServices are provided via features like VMotion, Storage VMotion, VMware HA, VCB, and—in the future—stuff like VMware Fault Tolerance (FT), formerly known as Continuous Availability. See this page on VMware’s site for more examples.
• Infrastructure vServices, like compute functionality (vCompute), networking connectivity (vNetwork), or storage features (vStorage). These vServices are manifested as features like VMware DRS, and will be extended in the future with things like vStorage Linked Clones, or 3rd party virtual switches, or VMDirectPath. The APIs are there for additional third party vServices to be added as well; one example would be network load balancing as an infrastructure vService.
• Cloud vServices enable the interaction of on-premise infrastructure (the servers in your data center) to integrate with external cloud infrastructure. There are no concrete examples to really share here; in my opinion, this is the most nebulous part of this announcement. See this page for more information.
• Finally, management vServices provide…well, management functionality for the virtual data center and the applications running in the virtual data center. More information is available here.

The way to really view VDC-OS is not as a “datacenter OS”, because it’s not intended to provide automation of non-virtual resources. Instead, look at VDC-OS as a framework. Within this framework are sets of services that can be extended or modified in very standardized ways (via APIs and SDKs) to provide different functionality for the applications running within that framework. Some third party ISV wants to write a different way of providing fault tolerance and failover? Fine, no problem, that can be plugged into the VDC-OS application vService framework for availability. I used the example earlier of a load balancer as an infrastructure vService. VMware announced the VMsafe APIs back at VMworld Europe, and the idea of VMsafe ties directly into API access for ISVs to develop new or different security-related application vServices that can be provided to all applications running within the VDC-OS, such as anti-virus or host-based intrustion detection/prevention.

I was a bit worried that this messaging wasn’t going to be received as clearly as I had hoped it would be, and the initial coverage I’m seeing so far confirms that many people are going to misread what VMware is trying to do. Hopefully, we can get the idea across to everyone so that they can begin to really understand where VMware is headed with this idea and why it is the next step in the evolution and maturation of virtualization.

New Features in VDC-OS

Now that I’ve gotten through the first part of discussing VMware’s VDC-OS announcement — making sure that the message and vision is a bit clearer — I can focus on some of the specifics contained within the announcement. In other words, I can talk about new features.

• VMware Fault Tolerance (FT), formerly “Continuous Availability,” (demoed at VMworld 2007, described in my liveblog here) provides real-time VM mirroring between two different hosts. If a host fails, the mirrored VM on the secondary host picks up automatically with no disruption to the users. Marathon Technologies is working on similar functionality for Citrix XenServer, and both companies are expected to deliver next year. If VMware wants a leg up on the competition, they need to deliver this first.
• The Distributed vSwitch enables administrators to define network settings at the cluster level, instead of on a host-by-host basis. This is huge for larger shops. Define your port group once, and you’re done.
• As has been pointed out elsewhere, Cisco is announcing the first third-party vSwitch for VMware ESX. Alessandro points out rumors that it will run NX-OS and will be a distributed vSwitch. In any case, it will certainly bring hard-core Cisco shops closer to embracing VMware as it will give them end-to-end control over the networking environment, all the way down to the virtual port level within any given VMware ESX host.
• vStorage Thin Provisioning will help on storage demands. I suspect this is just the use of thin provisioned VMDKs, but if anyone has any other information to share I’d love to hear it.
• Similarly, vStorage Linked Clones just brings to VMware ESX a feature that VMware Workstation and VMware Lab Manager have had for a while.
• VMware will finally enter the backup market with vCenter Data Recovery, which (to my understanding) will leverage VCB to provide a backup solution for the virtual infrastructure.

That’s quite an impressive list of features slated to be included in VDC-OS. What I’m also interested in seeing, though, is how the underlying components of VDC-OS — VMware ESX and VirtualCenter/vCenter — are going to change. I’ve seen rumors of 64-bit VMkernel and Console OS, and Duncan Epps points out linked vCenters (which is quite cool, might I add). I suppose that will be part of the “Tech Preview” sessions that are going on later this week at VMworld 2008.

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