|When it comes to saving their massive and ever-multiplying stores of digital assets, content creators can use any of the following techniques:
- Direct-attached storage (DAS), in which disk subsystems are directly attached to workstations or servers
- Network-attached storage (NAS), in which disk subsystems are directly attached to Ethernet networks
- Storage-area network (SAN), in which disk storage and servers are attached to a Fibre Channel network.
However, in most studio environments, the trend is clearly away from DAS systems and toward faster-performing networked storage architectures of NAS or SAN.
Jim Farney, senior marketing manager for media industries at SGI (and former longtime owner of a major postproduction facility), says that while most large studios already are using and benefiting from networked storage, smaller studios, which are still primarily using DAS systems, also could reap rewards from making the transition.
"Direct-attached storage poses problems in media environments because everything is a collaborative process, with many people having to manipulate content before it goes out the door," says Farney. "If you do it with direct-attached storage, you have to copy and move data over and over among graphics professionals. And as you move to higher resolutions and larger files, that becomes an onerous and time-consuming task." As a result, he says, there's a growing realization that professionals in collaborative environments have to move to some form of networked storage, whether it's NAS, SAN, or a combination of the two.
In addition to the content-sharing advantages of networked storage, studios may need the increased bandwidth of NAS, which attaches to 1Gbps (Gigabit per second) Ethernet networks or a higher-capacity SAN, based on the high-speed 2Gbps Fibre Channel network.
|The three primary storage architectures are direct-attached storage (DAS), network-attached storage (NAS), and a storage-area network (SAN).
"In the broadcast media space, there is a big trend toward networked storage because media facilities are moving huge amounts of content," echoes Jay Krone, a marketing director at EMC, whose Clariion storage systems were used by editors on a variety of films, including The Perfect Storm, Gladiator, Mission: Impossible—2, American Beauty, and X-Men. Indeed, a 90-minute feature film in uncompressed HDTV format could require more than a terabyte of storage capacity, he notes. Moreover, handling such massive files efficiently requires the high bandwidth available only in networked systems.
For digital content professionals working in collaborative environments, the primary advantages of NAS are its low cost (compared to SANs) and its facility for file sharing (as opposed to DAS). To enable file sharing among diverse platforms, virtually all NAS servers support CIFS (the network protocol for Windows platforms) and NFS (for Unix platforms), and some NAS servers also support protocols for file sharing within Apple and other environments.
But whether NAS will serve your needs compared to a higher-cost SAN depends on your bandwidth requirements. "NAS works great, if, for example, you're doing standard-definition digital-video editing with four or five video streams at up to 50MBps (megabytes per second) per client," says Gerry Johnson, senior product manager at Ciprico, which supplies digital media storage systems.
"But NAS may not provide enough performance in film editing environments that require throughput of, say, 200MBps and 2K-by-1K film-resolution playback in uncompressed format," says Johnson. The reason is that NAS file servers are typically attached to Ethernet networks, the fastest of which currently run at 1Gbps, versus 2Gbps for Fibre Channel. Gigabit Ethernet is rated at a maximum of 125MBps, although in reality, users may achieve only 60 to 70MBps because of network overhead. Therefore, according to a variety of storage vendors that focus on media applications, Gigabit Ethernet may be a good choice when many clients must access files, but not when they have sustained requirements for transferring large amounts of data, as is required in a renderfarm, for example.
Gigabit Ethernet networks have boosted the throughput you can get with NAS servers and have enabled high-speed file sharing in media applications. But the real breakthrough will come with 10Gbps Ethernet, which is just starting to be used in IT environments. "Although expensive, 10Gbps Ethernet will enable more than adequate performance in all video environments, including high-definition video," says Johnson.
Another way to boost performance of NAS systems is to add TCP/IP off-load engine (TOE) cards, which are available from vendors such as Alacritech and Intel. TOEs accelerate NAS performance by off-loading TCP/IP processing from the host processor.
Is NAS ready for big-budget film and TV production? Absolutely, if a number of high-profile applications of the technology are any indication. In fact, in one of the most asset-heavy film productions ever undertaken, Weta Digital in New Zealand used NAS file servers from Network Appliance as primary storage for the special effects in New Line Cinema's The Lord of the Rings trilogy. Specifically, Weta used the company's F840 NAS systems, which Network Appliance refers to as "filers," for special effects and other content-creation work requiring terabytes of storage capacity, high-speed image manipulation (with single images that often exceeded 12MB), and more than 150 graphic artists. (Network Appliance NAS filers also are used to store the content on the film's Web site at www.lordoftherings.com.)
|Network-attached storage (NAS) file servers from Network Appliance were used by Weta Digital artists in the making of The Lord of the Rings trilogy.
Similarly, for a variety of high-profile TV productions—including the NBC movie Saving Jessica Lynch, heavily animated TV commercials for Hasbro, and a direct-to-DVD G.I. Joe film—Reel FX Creative Studios, a 3D animation and visual effects facility in Dallas, relied primarily on NAS file servers. The studio uses SGI's InfiniteStorage NAS 2000 systems for storage tasks performed during the animation, as well as during the effects, video editing, and postproduction work its artists performed on Windows, Macintosh, Linux, and Irix platforms—all of which can access the same images simultaneously without file copying.
Despite the performance and file-sharing capabilities of NAS, in the end, it may be its relatively low cost that is most appealing to studios with limited budgets. For example, Huge Systems, a storage vendor that specializes in the video and rich media markets, sells a 1TB NAS server for $10,600 and a 3TB version for $23,900. The company targets digital video and standard-definition applications with its NAS servers, according to Mike Anderson, chief technology officer at the company.
If a NAS system doesn't provide high enough performance, you may need to consider a SAN. For example, says Johnson, "If you have hundreds of seats in a collaborative environment with high-definition editing, then a SAN is the only way to go."
For studio environments, the primary advantages of SANs are consolidated storage, centralized management, and a dedicated high-speed network, typically based on Fibre Channel technology, which can potentially achieve speeds up to two times that of Ethernet networks. By comparison, a 1Gbps Fibre Channel network is rated at a maximum transfer rate of 100MBps, although actual speeds may be more in the 75 to 80MBps range. That's marginally faster than a Gigabit Ethernet NAS system, whose actual top speed is 60 to 70MBps. But a 2Gbps Fibre Channel network, which is rated at a maximum 200MBps, can achieve speeds of 150 to 160MBps.
The downside to SANs is that they're expensive compared to NAS and DAS options. Although difficult to show on a dollars-per-megabyte basis, the price differential becomes clear when you factor in the costs of specialized SAN hardware, which could easily eclipse the total cost of your workstations, graphics cards, and software. Pricing varies widely, but Fibre Channel host bus adapters (which are required for all servers and workstations attached to the SAN) can cost around $1000 per platform. And Fibre Channel switches are considerably more expensive than Ethernet switches—more than $600 per port. In addition, Fibre Channel SANs require new cabling, specialized expertise, and, possibly, SAN management software.
However, SANs do provide the ultimate in storage performance. And when coupled with shared file systems—from vendors such as ADIC (StorNext
File System), IBM (TotalStorage SAN File System), and SGI (InfiniteStorage CXFS)—they offer file-sharing features such as concurrent file access for collaborative work environments. Other options for SAN file sharing include Fibre Channel SANs that come bundled with shared file systems, including those from Avid and Pinnacle Systems, which specialize in the video/graphics markets.
Some of these shared file systems provide content sharing among diverse platforms, such as Windows, Unix, and Macintosh—a platform mix that is common in many studios. For example, SGI's CXFS file system supports Windows, AIX, Linux, Irix, Solaris, and Macintosh platforms.
|A typical hybrid storage architecture combines direct-attached storage (DAS) disk arrays with network-attached storage (NAS) over a Gigabit Ethernet network and a storage-area network (SAN) over a Fibre Channel network.
The NAS-versus-SAN decision may also come down to the type of content you're storing. "NAS is good enough for 8-bit standard-definition material, but if you need to share high-definition content, then a SAN may be necessary," says Huge Systems' Anderson.
Although SANs provide high bandwidth and content sharing, some studios install a SAN for simpler reasons—at least initially. For instance, Tippett Studio deployed a SAN primarily to solve backup problems, according to Christian Rice, director of technology at Tippett, but in the end also used it for file sharing and content management (see "Tippett Banks on a SAN," pg. 46).
The various storage architectures (DAS, NAS, and SAN) are not mutually exclusive. In fact, a variety of vendors sell bundled solutions that combine elements of NAS and SAN. EMC, for example, has software that enables users to combine its Celerra NAS servers and its SAN-attached disk arrays. This approach allows users to mix NAS and SAN according to bandwidth and budget requirements.
"Professionals who need really high bandwidth, such as for renderfarms, can use a Fibre Channel SAN, while everybody else uses less-expensive NAS on existing Ethernet networks," says SGI's Farney.
"NAS-SAN convergence will be a big trend in studio environments that have a mix of bandwidth requirements," Farley adds. "You get the low-cost, file-sharing benefits of NAS with the higher bandwidth of a SAN."
Dave Simpson is editor-in-chief of InfoStor magazine. He can be reached at email@example.com.
Tippett Studio, a visual effects facility in northern California, faced huge amounts of data as it was working on films such as The Matrix: Revolutions, Stepford Wives, Hellboy, and Starship Troopers 2. To cope with the rapidly increasing storage capacities required for those projects, the studio installed a storage-area network (SAN) in mid-2003.
Originally, Tippett's storage infrastructure was based primarily on direct-attached storage with some network-attached storage (NAS) systems. "The main reason we went to a SAN was so that we could back up all our data without impinging on server bandwidth," says Christian Rice, director of technology at Tippett. "Our disk capacity is doubling every year or so, and sometimes we generate more than 200GB of new data every day."
At the heart of the SAN are two 16-port, 2Gbps Fibre Channel switches from Brocade, which attach to the studio's servers, storage arrays (most of which are from SGI), and backup systems. The SAN has hundreds of client workstations (mostly Linux and Windows), and a total storage capacity of 16TB, which is expected to increase to 19TB in a month or two.
|By migrating to a storage-area network (SAN) Tippett Studio enabled better content management, sharing, and backup.
Beyond enabling better backup operations (without impeding overall performance), the SAN provided Tippett centralized storage and content management, as well as data sharing via SGI's CXFS shared file system, according to Rice. The SAN also allowed Tippett to balance work loads across the storage network to optimize performance, he says, "and to export data to clients much more dynamically." —DS