Bake-off: 4 Virtualization Suites (In One Review!)

VMware Infrastructure 3
VMware, on track soon to go public via a partial spin-off from EMC, took first place, offering the best virtual environment for application development. The vendor's main advantage comes from its key product, Lab Manager, a Web tool designed to support software developers and testers in highly distributed environments.

The end-to-end software life-cycle management capabilities provided by Lab Manager were unmatched by any of the other products reviewed here.

Before installing Lab Manager, ESX Server, part of VMware's Infrastructure 3 suite, must be installed on one or more x86 physical servers. The next step is to install the VirtualCenter Management Server, which runs on top of a Microsoft Windows machine and is the control point for multiple ESX Server hosts. The next step typically is to start creating virtual machines (VMs) from existing physical machines using a tool called VMware Converter, which is the vendor's physical-to-virtual conversion tool.

VMware Converter takes the boot and data disks from a physical machine and converts them into bootable virtual disks in the container formats that VMware ESX Server can use to run virtual machines.

VMware limits guest OS memory to 16 Gbytes. Memory as well as other resources are reserved for a VM and always given to that machine as long as it is not idle. VMware also identifies an OS installed on a host and saves only one copy of the common memory page while keeping track of the differences. VMware calls this feature transparent memory page sharing. The end result is that administrators can power on VMs with more memory allocated to them than the actual physical memory of a host machine.

ESX Server provides a sophisticated network configuration by creating virtual bridges between physical NICs and virtual NICs. The NIC configuration feature can also group virtual NICs into teams to increase the fault tolerance of a system. This option is great for clustering and high availability setups. Administrators can take advantage of more capable hardware on a server by letting VMs connect to a NIC team.

ESX Server's storage settings are complex since they depend on direct-attached SCSI disks connected to remote Fibre Channel SANs. Each VM has a view of its storage disk as it was attached to a SCSI disk. In addition, administrators can connect multiple virtual disks to a VM. All virtual disks look like they are attached to the machine.

VMware's VMotion live migration technology is capable of transferring VM images on a single SAN, so the migrations are performed extremely fast. ESX Server now has the ability to manage clusters of physical hosts that are treated as a single resource pool. With ESX Server installed on several host machines, administrators can treat them as a single pool of CPUs, memory and stored resources, and deploy virtual machines across clusters of hosts.

With an ESX Server in place, it's up to Lab Manager to oversee the development life cycle. Lab Manager 2.5 installs on a server or a VM. Through a browser, administrators can set up server pools using a library of VM configurations. The server pool can connect to Microsoft Active Directory so it can take advantage of existing user accounts.

Lab Manager behaves like a source-control tool in that developers work with libraries and must check out applications. However, that's as far as the similarities go. It more closely resembles a provisioning tool that works with physical configurations on which software can be developed and tested.

Lab Manager looks across a pool of ESX Servers and moves each VM to the best host for each application component. By checking out a VM, developers immediately get to see all the components associated with an application. The check-out process takes VMs out of suspension, allowing developers to start from the same point as testers.

What's more, Lab Manager allows developers to open and work on multiple consoles simultaneously that are being viewed from a single Web page. This technology allows developers to treat multiple VMs as a single application. Lab Manager can also check out a configuration on developers' work spaces by copying VMs, a useful feature when testing.

Instead of making complete copies, Lab Manager actually creates linked clones to the disk images that represent the VMs. As developers make changes in a VM, only the deltas are saved by a configuration. Whenever the delta files are applied to the base images, developers can get back to the changes where the test states have been made. Since the delta files are small, many developers can work on each image independently.

Once code is fully tested, it's usually pushed to an IT change- management group, where developers do all integration work and stage up the application. Administrators push applications into production and manage them once they're there. VirtualCenter comes into play once applications are running in production. VMware makes the process seamless.

Next: XenSource XenEnterprise 4.0