Virtualized media data centers
Sep 1, 2010 12:00 PM, By Luc Andries
Implementing a virtual media data center shortens transport paths and simplifies data flows compared with other typical file-based media architectures.
Media companies have embraced IP-based architectures as the standard solution for file-based media production. This evolution enables today's media environments to treat video as ordinary files, independent of the video format. On a broader scale, it has launched a paradigm shift away from closed, proprietary media workflow solutions and toward architectural solutions constructed with generic IT technology.
The innovation of Data Center Bridging (DCB), including the creation of a lossless, high-quality storage networking environment, puts the Ethernet-based network at the center of both storage and client infrastructures. (See the article “Employing Data Center Bridging in media networks” in the January 2010 issue of Broadcast Engineering.) However, potential problems remain when porting media applications to a file-based environment.
The high throughput and quality demands of file-based media production require powerful, scalable storage systems with lossless characteristics. At the same time, the peculiar “bursty” characteristics of media file transport to client applications, such as high-resolution post-production editing, pose similar requirements for the IP client network — requirements that only data center networks have historically addressed.
Figure 1. Classical IP network-centric file-based production infrastructure. Click on image to enlarge.
Media production workflows are typically complex and dynamic, integrating many different media services (i.e., ingest, storage, transcoding, etc.). Given the heavy transport demands of media, most media services would benefit from being physically closely coupled with the clustered storage. Hence, the optimal media workflow architecture should integrate both storage and media services within a storage cluster environment, based on a scalable virtual platform.
Our laboratory tested the viability of a virtualized media data center architecture and found that this approach simplifies data flows, increases workflow efficiency and radically reduces overall workflow execution times.
Media-oriented architecture
The broadcaster back office has evolved to accommodate file-based workflows in a largely unstructured, chaotic way. Often, vendors have created solutions for a particular media service without taking the complete technology picture into account. As a result, most architectures today simply link multiple self-contained media service products — each with its own local storage, servers and network — in a best-effort mode via the central IP network.
Figure 2. Media data center solution. Click on image to enlarge.
This approach creates a great deal of duplication and complexity, to the point that the system is nearly unmanageable. Even more problematic, the architecture becomes heavily dependent upon the central IP network — a network composed of classical IP switches designed for the IT world, which are no match for the bursty nature of media traffic. (See Figure 1.)
Because most media services (and their local storage and servers) reside in the client IP network in a loosely coupled way, the overall infrastructure consists of file-based islands. Most data traffic is launched by the media asset management (MAM) application or the media applications themselves, independent of each other and unaware of the underlying architecture. Effectively, traditional sequential tape-based workflows have been replaced by almost identical sequential file-based workflows. This leads to inefficient data flows, as files are exchanged back and forth between islands in an any-to-any traffic pattern, with many duplicated copies. Because of the bursty nature of the traffic, packet loss results in unpredictable transfer delays or even transfer loss. Fortunately, we can envision a solution.
The reason many media services use local (and often, proprietary) storage is that they require processing power close to that of a storage service. The straightforward answer then is to unify local server and storage platforms for all services into a centralized platform — a virtualized media data center. Assuming such a platform meets several core requirements (guaranteed throughput, linear scalability, high reliability, support for multiple operating systems, flexibility and efficiency through service virtualization, etc.), it can create a much simpler, more efficient architecture. (See Figure 2.)
In this scenario, almost all media services run on the processing nodes of the virtualized media data center cluster and use the cluster's uniform central storage. This scalable clustered system now replaces the IP network as the basic platform for interconnecting media services.
Virtual media data center
To test the viability of this approach, we created a media data center architecture using a DCB-based Workhorse Application Raw Power (WARP) media storage cluster employing IBM's General Parallel File System (GPFS), the Cisco Nexus 5000 DCB switch and Cisco's Unified Computing System (UCS-C) servers. (See Figure 3.) As demonstrated in our previous tests, a DCB cluster with Priority Flow Control (PFC) implemented can sustain 100-percent efficiency and ideal scalability in file-based media environments. (See the article “Building IP-centric media data centers” in the March 2010 issue of Broadcast Engineering.)
The DCB cluster enables the physical machines of the processing network-attached cluster (NAN) nodes to run different operating systems (Windows, Linux, etc.) and run multiple media services using different operating systems within the same cluster. However, we can optimize resource utilization of these processing nodes by defining multiple virtual machines on the physical NAN nodes. Each virtual machine acts as a GPFS cluster node, meaning that the same physical machine can now run multiple instances of different operating systems, creating a virtualized architecture. (See Figure 4 on page 50.)
Optimizing workflows
Implementing media services on the processing nodes of a virtualized media data center mounted on clustered, lossless central storage can shorten the transport paths and simplify data flows considerably, increasing workflow efficiency and optimizing the client IP network. To demonstrate this, our lab tested a relatively simple workflow example: the ingest of a video clip from a file-based camera into the central storage, and the selection of the material and transport to a high-resolution editing station.
Continue to next page
| Want to use this article? Click here for options! |  |
