Author:
Thomas M. Coughlin, President,
Coughlin Associates
With entertainment and media content increasing in resolution, content data files have swelled and data throughput has increased proportionally. At the same time content producers are under more pressure to control prices than ever before. Serial Attached SCSI (SAS)-based storage systems play a big role in making these seemingly contrary goals possible.
Digital Production Means Lots of Bytes
The introduction of digital production technology is a great enabler of professional creativity. It encourages new levels of realism and special effects in the content and increases the efficiency of production at the same time as it decreases the costs of production. Because of the ease of digital capture of video content, producers now shoot a lot more hours before editing. This results in many more hours of content than was the case for film capture, similar to the trend seen with the conversion from film to digital still photography.
Generally, digital content producers shoot 10X more hours of content than was typical with film production. Digital production has resulted in more content, and increasingly more content is kept on associated post-production storage systems. Furthermore this digital content is kept on-line for a longer period of time. Some facilities even use disk arrays for active archives.
As the resolution of video content increases, the digital storage required increases. Table 1 shows the bandwidth and one-hour storage capacity demands of typical professional media formats (including sound) and the primary applications in which they are used¹. Higher bandwidth results in greater production of storage content and thus more demand for storage capacity.
¹ T. M. Coughlin, 2007 Entertainment Content Creation and Digital Storage Report, Coughlin Associates, 2007 (www.tomcoughlin.com).
Table 1: Example of Raw Data Rates, Professional Media Standards
Feature film resolutions are on an upward roll, particularly for the very high end of the market. 2K resolution films are common and 4K resolution films are becoming more common. Table 2 shows some metrics for feature films assuming a 10-bit deep file.
Table 2: Feature Film Metrics (10-bit deep file assumed)
Tiering Storage in the Production Environment
Because storage system backplanes can be built to support both SAS as well as Serial ATA (SATA), storage system designers have more freedom in designing tiered-storage environments. SAS and SATA II support make it easy to create cost-effective multi-tiered storage solutions in a single cabinet, utilizing lower cost SATA drives for secondary storage while staging critical primary data on higher performance SAS disks.
Creating the potential for multi-tiered storage within one enclosure can be important, particularly for smaller studios since they may not use high-speed-storage networks and therefore workstations at these facilities benefit from having multiple storage options in direct-attached devices.
SAS in Entertainment and Media Storage
At the 2007 National Association of Broadcasters (NAB) conference last spring, there were many examples of storage systems and storage system components from many vendors that utilized SAS storage². Storage companies serving this market include several well known storage providers as well as specialized companies. Even the larger storage suppliers have specialized business units that service the entertainment and media markets.
Often storage system installation in a studio or other facility is done by companies specializing in these markets. Such system assemblers understand the requirements of this demanding industry. Because of the time-critical nature of this market, storage systems for the entertainment and media market are often over-provisioned to ensure that there will be no dropped data streams. With video work, a dropped stream can cause significant delays in an expensive facility.
Many of the storage systems utilizing SAS provide a high-performance storage system, often with a Fibre Channel interface. Some of these products offer storage prices as low as $1.31/GB and storage capacities up to 10.5 TB per rack with data rates of 380 MB/s sustained (enough to service 10-SD resolution streams). Some of these products allow a choice of SAS or SATA disk drives in a common backplane.
Some direct-attached storage products offer dual-controller active/active support, built in performance analysis and management, including drive rebuild. These products can often mix SATA and SAS disk drives for storage tiering. One system at NAB supported as many as 60 drives although it is being expanded to support up to 96 drives. Storage systems with capacity up to many tens of TBs are currently on the market, but with 1 TB drives ramping up (for SATA at least) these storage capacities will swell within the next year.
Such systems can offer truly huge data rates such as those that are required in a multi-stream studio environment. For instance using a dual-4X SAS host connection with dual-controller redundancy, such systems can provide 12 GB/s throughput. Other lower cost products use full-duplex SAS operation to provide 1.5 to 2.0 GB/s operating data transfer rates. These products may include SAS RAID controllers. Some of these SAS RAID controllers support multiple streams of HD video with parity RAID protection.
² T. M. Coughlin, Post Magazine Storage Supplement, May 2007.
SAS Increases Studio Efficiency and Production Throughput
SAS and SAS/SATA storage are key enablers of the modern digital video production industry. They enable robust, dependable storage arrays to support reliable, high-data rates and multi-stream video editing systems in both storage networking and direct-attached storage environments.
By being able to share resources with lower cost, high-capacity SATA storage multi-tier working environments can be created for even the most cost-sensitive facility. Such multi-tier environments make active working archives possible. These elements combine to make SAS a vital component in a cost-effective, high-efficiency editing and production facility.
Tom Coughlin, President, Coughlin Associates spent over 30 years in the data storage industry. Tom is active with IDEMA, the IEEE, SNIA and other professional organizations. He is Chairman of the 2007 Santa Clara Valley IEEE Section and the founder and organizer of the Annual Storage Visions Conference (www.storagevisions.com), a partner with the annual Consumer Electronics Show. Coughlin Associates provides market and technology analysis as well as Data Storage Technical Consulting services. For more information go to www.tomcoughlin.com.
