In the third installment of our Rolling Review of virtual desktop infrastructure solutions, we take Sychron's OnDemand Desktop for a spin. Before the big names in server virtualization started paying close attention to the potential of virtual desktops, Sychron was already making a name for itself as a thought leader for developing solutions that enable quick provisioning, management, and guaranteed performance of virtual desktops on a large scale.

As a result, Sychron is more of a management and front play in the VDI space that integrates with back-end hypervisors, most notably VMware ESX and Microsoft Hyper-V, to manage the delivery of virtual desktops to users.

Not too long ago, even VMware engineers would recommend Sychron as a provisioning platform for large-scale virtual desktop deployments. Of course, much has changed in the past two years, with Citrix and VMware both upping the ante with significant investments in their own connection brokering and provisioning capabilities. Having tested both VMware VDI and Citrix XenDesktop in our InformationWeek Labs, we sought to discover what OnDemand Desktop brings above and beyond what View 3 and XenDesktop provide out of the box. And most importantly, we sought to discover what business value OnDemand Desktop could provide to our fictional and geographically dispersed legal services firm, Bits and Bytes LLC (see the testing scenario in the Rolling Review kick-off).

The OnDemand Desktop portal installs on any server running Microsoft Internet Information Services 5,6, or 7, and back-ends to the OnDemand Control Center, which is the heart of Sychron's provisioning and automation engine. By creating what Sychron refers to as Habitats, administrators can associate a group of virtual desktop to a particular function, role, or Active Directory user group.

Of course, that's a basic capability that all connection brokers share. What really makes OnDemand Desktop Habitats useful is the way Sychron exposes certain metrics and benchmarks that can be used to tweak performance and the overall user experience. For example, to provide quick access for 20 sales employees to share a pool of 20 virtual desktops in Xen and VMware, the virtual desktop needs to be spun up and prepared for access, and that takes time and uses system resources.

Sychron Habitats take a different approach, allowing the administrator to define upper and lower boundaries of virtual desktops that are waiting on demand. In the lab, we created a habitat with a lower boundary of five virtual machines and an upper boundary of 25 VMs, which is the maximum number of desktops allowed to be spun up simultaneously in each Habitat. The OnDemand command center did a good job of dynamically managing load by spinning up more VMs as the lower boundary of active connections was approached, effectively keeping ahead of the demand curve to ensure quick access to virtual desktops for employees. If your user population is an impatient lot, then you'll appreciate the difference between waiting three seconds and 30 seconds for a desktop to load.

As users log off for the day, OnDemand dynamically spins down virtual desktops and recovers system resources. Equally notable was Sychron's ability to ensure virtual desktop availability to VIPs in the event of low system resources or a broken cluster. Using a Habitat parameter that OnDemand refers to as a business priority field, administrators can ensure that, for example, the sales group is able to access virtual desktops ahead of the human resources team.

Another major benefit of OnDemand is its ability to easily build clusters with dissimilar hardware by simply adding the IP address of additional OnDemand portal servers that exist in the environment.

Provisioning capabilities in OnDemand are on par with the other players in this Rolling Review. Master images can be easily updated to quickly deploy application updates and patches to Habitat members, while individual user profiles are managed and preserved separately from the master image. OnDemand does a good job of giving the administrator plenty of options for automatically timing out or logging out virtual desktop sessions when updates to the master image are ready to deploy.