- Technologies
- FC-AL: A First Step
- SAN Setbacks
- Technology and Configuration
- High Scalability and Flexibility
- Technology Platform, Techniques, and Alternatives
- Breaking Tradition in Video Distribution
- SAP R/3 Storage Management
- Conclusion
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Breaking Tradition in Video Distribution
Today's workstation-based video-creation and manipulation tools allow users to treat video as discrete chunks of images and sounds that can be manipulated in various ways. This abstraction provides the freedom to focus on content generation rather than the tools used to create the content. Yet, while the latest video tools allow far more creativity and functionality, the way video is distributed among these tools remains unchanged.
Storage area networks (SANs) are the basis for a new video-distribution system. They allow the video moving between the tools to be treated in the same way as the video inside the tools—as discrete chunks of images and sounds. SANs empower entire teams of people to focus on the process of creation and creative collaboration rather than on how to best move materials between workstations.
Purely Analog Video
To the video pro of the 1970s, video seemed as if it was a constant flow or stream of information. Thus, it was natural to develop a method of distributing analog video throughout a video-creation or manipulation facility (TV station, production facility, post house, and others) that resembled standard water plumbing. Video coaxial cables (pipes) connected VTRs (water tanks) with mixers (faucets), monitors (sinks or tubs), and cameras (artesian wells). A video tape recorder (VTR) would continue to play or record (much like an open faucet), even with no mixer or monitor or camera connected, blindly spraying video into the ether or recording only the Brownian motion of magnetic particles.
In most video facilities, a crossbar switch installed within this equipment essentially allowed a temporary replumbing of the many pipes connecting the various video devices. With this crossbar, or video-routing switch, a temporary connection could be made between any of the inputs and outputs of the switch. Video poured into the plumbing system at one end would be guaranteed to spray out the other in common—they add an abstraction layer that insulates users from the complex technology that makes them work.
Today's dominant operating paradigm of the nonlinear editing system strives to remove any trace of the linearity of videotape or the complexity of video digitization and manipulation. Instead, it presents only a timeline on which to place various-sized chunks of video. Any video tool using the nonlinear paradigm works roughly the same way. Video does not seem to flow in today's video workstation; instead, the flow has been frozen into chunks that are simply stacked end to end along the time line.
The video-distribution systems in most facilities, however, were meant to handle flowing video, not frozen chunks. To move frozen chunks of video between workstations, they must first be melted back into a liquid stream and refrozen at the next workstation. While serial digital video in SDI and SDTI formats is an attempt to keep video in its frozen state, or at least in a slush, some customers are still less than satisfied. At best, just the conversion from the 4:2:2 YUV format used in SDI to the 4:4:4 RGB used by many computer-based workstations concerns some high-end post facilities. At worst, there is a question as to why video must be moved or copied at all.
In an effort to come up with something better, some video-creation and manipulation facilities have explored the use of standard computer local area network (LAN) technologies such as Ethernet and ATM. But LANs are not quite fast enough to give every video workstation an uninterrupted supply of video as needed. LANs do, however, provide a view of a better way video could be distributed in a facility.
The Introduction of Digital to Video
By the mid-1980s, the video frame buffer forced many in the video business to realize that video is not really a stream of flowing information, but a collection of discrete chunks of information in time that can be controlled and manipulated as desired (something that the film industry had known all along). Initially, the most flexible and affordably sized chunk of video was a frame, or actually, two fields. It was quickly discovered that, with the proper hardware and software, frames of video could be manipulated individually and even reordered to convey a different message, tell a different story, or alter video reality.
By the end of the decade, video-manipulation functions were performed in software running on standard off-the-shelf computers enhanced with specialized video input/output boards. These new video workstations were a normal evolutionary development. The designers of the next-generation video equipment determined that, to remain competitive, expertise must lie not in building special-purpose computers for video, but in building special-purpose video boards and software to work with general-purpose computers.
The Video-Creation and Manipulation Workstation
From a distance, video workstations and the applications that run on them all have one characteristic in common: They add an abstraction layer that insulates users from the complex technology that makes them work.
A Faster Network
A close examination of a video facility with multiple video workstations connected together with a LAN reveals a commonly overlooked solution to the lack of speed provided by LANs when used for video. Most video workstations have not only a relatively low-bandwidth connection to the LAN, but also a relatively high-bandwidth connection to their local storage. This connection to local storage, whether it is through a disk medium channel such as SCSI, SSA, or Fibre Channel, provides data to the video workstation at speeds many times greater than the LAN can provide.
From the perspective of a wiring diagram, a SAN is very similar to the traditional streaming video and routing switcher system. But a look just beneath the surface reveals that the two diagrams represent completely opposite operating paradigms:
Instead of a highly intelligent and expensive data storage device, a VCR, a SAN uses a dumb and relatively inexpensive data storage device: a disk drive.
Instead of a dumb, manually operated and slow central circuit switch, a video-routing switcher, a SAN uses a very intelligent, automatic, and extremely fast central packet switch: a Fibre Channel switch.
Instead of passive manipulation devices that perform actions on whatever is fed into them, such as DVEs, mixers, monitors, and others, a SAN uses extremely active and intelligent manipulation devices that must request the data on which an action is to be performed, like video workstations.
Instead of data being blindly pumped down a pipe by a storage device with no knowledge of what is on the other end of that pipe, a SAN sends data to only the manipulation devices that request the data4.
Push Versus Pull
To date, video distribution in facilities has employed a push metaphor, like water pumped out of a tank, a fine example of the classic mid–20th-century centralized command operating paradigm—the way our grandfathers liked to build things. Video distribution with a SAN uses a pull metaphor, similar to the World Wide Web. Intelligent clients request data from distributed storage, and the data flows to them as bursts of data packets that they assemble and use as they desire. This is a good example of an early 21st-century object-oriented, distributed local intelligence operating paradigm. Yet, this 21st-century operating paradigm, using a SAN for distributing media throughout a video facility and a file-level SAN O/S such as Tivoli SANergy File Sharing, allows many capabilities that are impossible with the existing method of distributing video in a facility:
No more Sneaker-Net—SAN users can access all video materials on shared storage; thus, the need to carry disks or tapes between workstations for reconnection or redigitization is eliminated.
No more copying—Instead, SAN users avoid the need to copy materials from a server or other workstation to their local workstation and, thus, avoid the time spent waiting for those copies to occur. A workstation connected to a properly designed SAN can read and write the same files on the shared storage simultaneously with every other workstation.
Increased reliability—Fault-tolerant RAIDs guarantee that if a single disk in the RAID fails, none of the data is lost.
Increased work flexibility—With multiple identical or similar workstations running the same applications all connected to the SAN, there is no reason that a job cannot be started on one workstation and finished on another. Moreover, if one workstation fails, the job can be continued from any other workstation on the SAN.
Increased application flexibility—If the latest and greatest application happens to run only on the Windows NT platform, files can still be shared between it and all the existing Macintosh and SGI workstations.
Increased storage efficiency—With the centralized shared storage possible with a SAN, each workstation can use as much storage as needed for each job. With more than enough gigabytes shared between a few workstations, everyone has all the storage they need, and no one has leftover storage being wasted.
Decreased overall storage—Because multiple workstations can use the same materials at the same time, the volume of online materials is reduced; thus, the total storage requirements are reduced.
Quieter edit suites—A Fibre Channel–based SAN allows up to 6 miles between devices. This allows many SAN users to move their storage into a soundproof, climate-controlled room separate from the edit suite.
Simultaneous backup and restores—It is possible to back up and restore files from and to the shared storage while other users are accessing the storage. This capability eliminates middle-of-the-night backups and emergency "everyone stay off the network" restores.
Easier segregation of tasks, reduced number of VCRs—Some facilities find it more efficient to have a single NLE devoted to digitizing materials and outputting finished programs to tape. If the collaboration on jobs at a facility allows this type of work flow, it is possible to save the cost of a VCR for each edit bay. Also, the creative staff can focus on their work and leave the repetitive tasks to other personnel.
Simultaneous viewing of the same work—Similarly, some facilities find that having an additional NLE for client viewing improves efficiency by reducing interruptions. With a viewing station, clients can essentially look over the shoulder of an editor at work, without interrupting the creative staff—in fact, even without their knowledge.
Improved visual quality—The near-perfect form of video is as frozen chunks. A SAN linking video workstations minimizes the number of freeze and thaw cycles and helps preserve the visual quality of the video.
Overlapping and pipelining processes for faster job completion—With a SAN, it is no longer necessary to wait for an entire chunk of video to be processed before starting another process on that video. As soon as one frame has finished the first process, it can be used on a workstation located elsewhere on the SAN.
Better collaboration, better productivity—The speed-up in work flow enabled by a SAN allows people to collaborate more easily to create better projects or to reduce the time that a single project takes to complete4.
SANs in Video
SANs are the basis for a new video-distribution system that seamlessly matches the recent advancements in video creation and manipulation systems. SANs provide many advantages over the traditional streaming and routing switch distribution systems. Using a SAN with a SAN O/S such as Tivoli SANergy File Sharing, today's video post-production facilities can complete the transformation begun by modern video-creation and manipulation tools and can become highly efficient, collaborative environments designed to maximize creativity, profitability, and system availability.
Recent new products such as Systeme, Anwendungen, Produkte's (SAP's) Business to Business Procurement, e-commerce portals, and the emerging SAP application service provider markets require an ever-increasing need for continuous system availability. This last part of the article provides information on an essential component of required advanced infrastructure solutions: the high-availability split mirror backup/recovery.
NOTE
Systeme, Anwendungen, Produkte (SAP) in der Datenverarbeitung (German: Systems, Applications & Products in Data Processing) is the German software company SAP AG. SAP's R/3 integrated suite of applications and, its ABAP/4 Development Workbench became popular starting around 1993.
The described split mirror solution delivers a backup with no impact on the live R/3 System (serverless) using advanced functions of IBM's Enterprise Storage Server (ESS). This zero downtime for the live R/3 System means that SAP users do not miss a beat while the backup takes place. No transactions are canceled during the copy/backup process.
Instant availability of consistent copies of the database provides the ability to place an emergency system at the user's disposal while recovering the live database from a disaster. Beyond backup/recovery, a consistent copy of the live database may be used for various purposes, such as the creation of a business warehouse (BW) system.