The ability to stream broadcast-quality audio/video files within a collaborative LAN or WAN setting while guaranteeing QoS is in its infancy. Tens of gigabits per second must be available through the network for multiple users to share uncompressed digital content over the network in real time.
The strategy chosen to seamlessly integrate storage with the production environment largely determines the total cost of ownership. It is important to look at the problem from the viewpoint of hardware system complexity and at how the system improves workflow efficiency.
Streaming bottleneck
A major goal of a multi-seat HD production environment is that all users would have real-time access to the content. Storage capacity and processing power have increased by hundreds or even thousands of times, but disk drive performance has only increased a modest fourfold, due to mechanical limitations that hamper seek, read and write times. This can be a serious problem when multiple copies of an asset are requested — reducing I/O throughput by as much as 90 percent.
Attacking the problem head on
The most straightforward approach to this problem is to de-couple the I/O performance of the server from the performance of the disk drives. Utilizing existing solid-state memory, processing and software technologies, streaming servers can be developed that no longer depend on attached online disk storage. Whereas today's streaming servers struggle to provide a few hundred megabits per second of streaming performance, a solid-state system at roughly the same, or even less, cost could stream tens of gigabits per second. Expensive SCSI and Fibre Channel disks and SANs can be eliminated, and streaming content can be sourced directly from lower-cost ATA/IDE disk-based archive systems over LAN or WAN connections.
Exavio's solution allows operators to scale the storage capacity independently of the throughput. The solution consists of two separate subcomponents. The high-density and low-cost media storage system, ExaVault, provides access to digital content through file- or block-level access via Ethernet or Fibre Channel interfaces. Using current drive capacities, one of these subsystems can scale from 3TB up to 120TB. The second piece, the ExaMax media switch, is a media pumping engine with solid-state memory and powerful media processing capability that incorporates intelligent caching, guaranteed broadcast-QoS delivery, and support for scalable and variable bit rate streaming without the need for provisioning. The switch, which can aggregate storage capacity and bandwidth in combination with the storage subsystem, will seamlessly interconnect enterprise and broadband service provider networks over an IP-based infrastructure.
Figure 1. Exavio’s ExaVault works with the ExaMax media switch to aggregate storage capacity and bandwidth while guaranteeing QoS in a multi-seat production enviroment. Click here to see an enlarged diagram.
The media switch directly interfaces with multiple end-user workstations to provide file- or block-level access to the media content. It provides high-quality and reliable transfers of data to the end user from local or remote storage systems. With this capability, the user can reduce the requirement on the underlying data transport network, along with the data loss, data jitter and out-of-order packets that plague today's low-cost networks (see Figure 1).
By combining this technology with Gigabit Ethernet and Fibre Channel-based storage solutions, it is possible to provide high-throughput connections between multiple networked workstations and shared storage over today's LAN or WAN, without the need for dedicated SAN infrastructures. Operators would be able to retrieve multiple uncompressed HD files over the network, while performing special effects and nonlinear editing, all in real time. Processed content could then be transferred back to shared storage for other members of the team. Eliminating time-consuming data transfers between digital tapes and storage, as well as enabling operators to work in real-time, will greatly improve efficiency and lower production costs. It's conceivable that such technologies will also assist in lowering the cost of deployment for broadcast servers.
Ji Zhang, PhD, is president and CEO of Exavio.
