Video Site Virtualizes I/O, Servers

Pixorial is a new consumer Web site designed to let people upload their home videos, but unlike YouTube, it wants users to be able to edit, then share the edited videos through a link on a personal Web site. Consumers can link to a free, low resolution version of a video they've created that's stored and played on the Pixorial site, or they can pay a $1.99 fee for a higher resolution version. They can also order a DVD for another small fee.

When a visitor to a Pixorial customer's personal site clicks on the link to see a home movie, a player on the Pixorial site then displays the edited film. As a result, Pixorial.com is a demanding, "media-type-agnostic" IT environment that has to move a variety of large files around fast, while still operating in an economical manner.

It sounds like a problem for virtualization; actually, it's two problems.

The first is putting enough virtual machines on Pixorial's three Dell PowerEdge 2900 servers to handle the video files efficiently. The 2900s are optimized for virtualization and can be equipped with up to 48 GBs of random access memory. Each of Pixorial's is equipped with two quad-core Xeon CPUs and is "running 18-20 VMs each," said Joshua Terry, Pixorial's director of systems engineering, in an interview.

At peak operation, those VMs are transferring 700 GBs of video files from one device to another a day in high definition DVD format or 3GP cell phone video. Another task the site performs is digitizing VHS analogue tapes sent to Pixorial so they can be stored, then edited digitally.

The second virtualization challenge is overcoming the tendency of virtual machines to choke on large amounts of storage or network I/O, even when there's sufficient CPU to execute all the file-handling tasks. At the outset of public operation in April, each virtualized host with its heavy I/O workload appeared to be a Heimlich maneuver waiting to happen.

Terry said he solved the issue by installing an Xsigo I/O Director, a separate piece of hardware to which the VM's offload their I/O. It moves video files from storage directly to the appropriate virtual machine, whether it's a converter system, an editing system, or a player system, depending on the function needed.

Xsigo I/O virtualization requires specialized Xsigo network interface cards on the Dell servers to move both storage and network I/O to the Xsigo switching machinery nearby.

In order to handle large video files, Pixorial implemented the former SGI's XFS file system. To get the Xsigo to work with its film handling applications, Xsigo had to "custom compile the driver for an Xsigo controller" so Pixorial could still use XFS.

"We needed a set of technologies that were flexible and would adapt to the bandwidth we would require," said Terry. The ability to add or subtract virtual machines using virtualized I/O proved to be the way Pixorial wanted to build its site, he said.

Pixorial's overall goal is to enable consumers to do more with their personal video than they thought possible -- more than simply uploading video to another YouTube-like site. It makes its editing application easy for end users to use, "not a FinalCut Pro type of editor," but behind that ease of use stands a virtualized infrastructure that has to move video files around quickly. So far, growth has proceeded in modest increments, but Pixorial wanted to build in the capacity to grow if the site caught on. "We wanted to be sure to adopt the technology that could mitigate the pain of growing quickly. I don't think we would have been able to deal with this much bandwidth without Xsigo," said Terry.

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