Not many products truly deliver what they promise. Scalent V/OE (Virtual Operating Environment) 2.0, however, comes as close to keeping its pledge as anything I've seen. Scalent is attempting -- and succeeding -- at reaching the pinnacle of datacenter management: a truly adaptive infrastructure.
Scalent V/OE has three components -- a central Controller, Agents on the servers, and a nifty GUI Console -- that separate the server from the hardware, making it possible to move server instances, called "personas," between physical hardware and even between virtualization platforms in a seamless manner that retains all network, iSCSI, and FC (Fibre Channel) connections.
Meet your personas
I took a look at the forthcoming release of V/OE 2.0, and it's quite complex. It involves a controller built on a Red Hat Linux base that essentially has its way with all associated network switches and server hardware. Switch interactions are handled via SNMP; the server side is driven by IPMI (Intelligent Platform Management Interface)-compliant lights-out management features or a virtualization platform such as Microsoft Virtual Server, VMware, or XenSource.
Because of these requirements, V/OE has a relatively short list of supported hardware, including that of major vendors such as Cisco, Dell, HP, and Sun. I worked with a selection of servers, including three
HP ProLiant DL360s, a Sun v20x server, and a Dell PowerEdge 2800 that I added later in the testing. One of the DL360s was running VMware ESX Server 2.5.2 with a single local disk, and the others were diskless.
Installation is also quite complex, so Scalent sends an engineer to do the initial build of the infrastructure, including assistance in building the initial server personas.
A server persona is a server built for a certain task, replete with applications installed and configured. For instance, an Apache Web server could be built on any physical server, configured, have an application installed, and then be condensed into a persona. The same goes for Windows 2003 Servers, as well as for Sun Solaris 10 SPARC and x86 systems.
All of this is hardware-independent. A persona could be created on an HP ProLiant DL360, but then deployed on a DL380 or even as a VMware ESX 2.5 guest server.
There are some differences in the way personas are built, depending on operating system. Linux personas are generally built and run as netboot systems, with their file system residing on an NFS server central to the solution. Windows servers cannot leverage the netboot/NFS simplicity, and they are subsequently booted from an iSCSI or FC SAN that contains a disk image of the server. The iSCSI booting is handled via emBoot, with the initial boot stage run via PXE, the same as all other servers.
The Scalent Agent, the second piece of the puzzle, is the key to the true hardware/OS abstraction. Each persona runs an instance of Agent, which interacts with the controller to determine network and SAN connection parameters, IP addresses, and other ancillary data for the proper placement and configuration of the server persona on its hardware. Booting the server personas from the network also eliminates the need for a local disk on most servers.
What's relatively unique isn't so much the creation and management of the server personas but rather the persistence of this configuration data across multiple hardware platforms. It's done by clever use of 802.1q trunking and dynamic switch interaction.
Each time a persona is booted on any piece of hardware, the Scalent agent configures the network interface to be an 802.1q trunk back to the switch and assigns IP and MAC addresses to virtual interfaces within the OS. This ensures that the proper interface exists on the proper network with the proper IP information.
Moving a server persona from one server model to another -- and then to a VMware instance -- now becomes simply a task of instructing the PXE-booting hardware as to what image to load. Slick.