NAS vs. SAN: Storage Considerations for Broadcast and Post- Production Applications As more content is created in, and as the industry transitions to, higher resolutions, many broadcast and post-production teams are reaching the limits of their storage environments. Whether expanding, upgrading or building a new storage infrastructure, broadcast and post-production facilities have two primary, distinct technology options to consider: Network-Attached Storage (NAS) and Storage Area Network (SAN). Because both technologies represent a capital investment and come with their own strengths and weaknesses, it is essential to carefully consider all of the variables and make the right choice that will meet both current and evolving needs. White Paper
Introduction As more content is created in HD and as the industry transitions to 4K resolution, many broadcast and post-production teams are reaching the limits of their storage environments. With enormous volumes of data to store and move often hundreds of terabytes these environments can quickly run out of capacity or can t achieve the speed with which media files need to be accessed, manipulated and distributed. Whether a broadcast or post-production group plans to expand, upgrade or build a new storage infrastructure, they have two primary, distinct technology options at their disposal: Network-Attached Storage (NAS) and Storage Area Network (SAN). Because both technologies represent a capital investment and come with their own strengths and weaknesses, it is essential to carefully consider all of the variables and make the right choice that will meet both current and future needs. This paper outlines those variables and considerations, helping broadcast and post-production teams make the best storage decision for their particular situation and requirements. Two Primary Options: NAS and SAN While there are a number of storage technologies, two have become the de facto standards for broadcast and post-production applications: NAS and SAN. A NAS is a system that is directly connected to block level storage, sharing the data on that storage via remote file serving. Rather than accessing data from local storage, a workstation s file access is redirected to the NAS system (using a remote protocol such as CIFS or NFS), and the NAS performs the file I/O on the workstation s behalf. This enables file sharing typically over an Ethernet network and the centralization of data management. Because NAS takes advantage of preexisting infrastructure (i.e., a facility s existing Ethernet network), it is often less costly, faster to deploy and easier to manage than a SAN environment. But it comes with one distinct disadvantage: speed. Total bandwidth is limited, performance can be impacted by network traffic and broadcast and post-production teams can quickly run into latency and data-transfer issues. Due to these constraints, NAS is often utilized for archiving files that are not currently in use and infrequently accessed. Conversely, a SAN is connected in a fabric (usually through a switch) to facilitate easy access from many different servers and clients. From a server application and operating system standpoint, there is no visible difference in data access from a SAN or from storage that is directly connected, such as an external hard drive. SANs are usually run over optical fiber cabling and utilize Fibre Channel switches, but instances of running them over Ethernet (iscsi, FCoE) are starting to pop up. Figure 1. Example of NAS architecture 2
While a SAN is typically more costly and time-consuming to implement than NAS, it will pay significant dividends in performance. Speed is the primary advantage of SAN environments, deftly meeting the (continually increasing) performance requirements of broadcast and post-production applications. Access to large media files is instantaneous, even from a multitude of systems. This is especially valuable for post-production activities where a number of users and systems must access, manipulate and transfer files in synchronous fashion. With better redundancy than NAS environments, SANs also deliver unwavering uptime and availability critical for broadcasting purposes. They provide more robust physical and virtual security. And because SANs can be aligned with different storage systems, they deliver greater flexibility for future growth and archiving purposes. Primary NAS advantages: Cost Implementation Administration Primary SAN advantages: Speed Availability Security Flexibility Figure 2. Example of SAN architecture Imperative #1: Capacity Capacity is always a concern when making storage decisions. Both SAN and NAS are scalable, but in fundamentally different ways. NAS environments can be easily and organically expanded over time, but storage sprawl and the administrative hassles that come with it are often the consequence. SANs are not as easily scaled, but they deliver more flexibility. Because they can be aligned with cloud, tape and even NAS environments, SANs lend themselves to a tiered approach featuring multiple storage solutions. This means broadcast and post-production teams can get the best of both worlds: high-performance for files in use plus cost efficiency for archival purposes. It is important to consider both current and evolving needs when making a storage decision, as capacity requirements will inevitably grow. When planning for future growth, The Rule of Two often applies. Get 2x the bandwidth, 2x the capacity and 2x the infrastructure that you need now, and be sure you can expand with a second unit if required. This all depends on budget, of course, and is a general rule of thumb more than a rigid requirement. You don t want to outgrow your new storage system in a short amount of time, only to realize that better planning and a bit more upfront investment could have saved much more time and money in the long run. For example, if you are planning to have four edit bays streaming 4K movies, with each movie taking up 25TB in its raw form, you probably need 200TB (at a minimum) of storage to handle it. Remember, you need space to store your raw masters and room for any renders, encodes, transcodes, versions, CC-data, etc. Not provisioning enough capacity at the outset can end up wasting significant amounts of time after the storage is commissioned, with administrators having to constantly juggle archiving and file deletions in order to free up space for the next project. 3
Imperative #2: Speed Beyond capacity, the most significant variable and consideration and the biggest difference between NAS and SAN is performance. In the broadcast and post-production world, time is money. Latency and transfer issues can dramatically impede the speed and efficiency of post-production teams and the same issues can thwart on-air broadcast transmissions altogether both of which will have a direct financial impact. Simply put, upfront cost savings related to storage can result in a significantly more expensive post-production workflow or broadcast pipeline if performance requirements aren t met. In general, here is the bandwidth required per stream: 4K real-time uncompressed = 1200-1600 MBps 2K real-time uncompressed = 300-400 MBps HD real-time uncompressed = 250-300 MBps SD real-time uncompressed = 30-50 MBps Compressed video = varies by compression type However, these are general numbers that can be impacted by a variety of factors, including bit depth, color depth, etc. Figure 3 provides more specific numbers in the context of DPX. Figure 3. Required data rates and file sizes (DPX) 4
It s also important to consider the bandwidth vampires. These are systems that nobody thinks about in the initial planning, but will suck up a significant amount of bandwidth and can become a nightmare down the line if you cut the speeds too close to the bone: Transfer and I/O Systems (Drive Ingest, Aspera, FTP, Signiant, DigiDelivery, Satellite delivery, etc.) Tape backup systems Indexing applications (DAMs, Spotlight, Windows Search, etc.) Additional Considerations In addition to capacity and speed, there are several variables that should be considered when making a storage decision: Construction. One big consideration is whether you need to build out infrastructure for your storage purchase. If you go with a SAN, will it be possible to run fiber to each system? That should be easy if all the systems are in a server room, but if they are in their own editing bay, do you have the budget to hire a wiring company? Power and cooling are always a consideration at this phase. Both SAN and NAS usually have multiple drives. All those drives, plus their controllers and their chassis, will eat up power and require cooling. Having a new power box installed or a new AC unit dropped on the roof can get pricey quickly. Drive type. Whether it is SAS, SATA or SSD, the type of drives you plan to use should be considered. SAS drives spin at high speeds (15k or 10k rpm) and are dual-ported, allowing them to gracefully handle more concurrent requests at once. They also have lower latencies. These drives are used when frames absolutely cannot be dropped, when real-time playback of a movie must be perfectly smooth and when any additional time in post-production costs a tidy fortune per hour. SAS drives are usually the top and fastest tier in your SAN. SATA drives spin at a slower speed and usually have a much higher capacity. SATA drives sacrifice the top-end speed and ultra-low latency for capacity. They work great when you have very low bandwidth video requirements or workflows that don t require real-time performance. As NAS systems aren t the fastest option anyway, usually you will only find SATA drives installed. You will also find them in the second level, high-capacity storage tier for a SAN. SSDs are solid state drives, meaning they have memory chips instead of spinning disks. They are very fast, consume minimal power and deliver almost zero latency, but they are still very expensive and have a limited number of write cycles before dying. SSDs are getting cheaper, however, and their write cycles are getting better. They are a technology to watch, but as of today, they only fulfill niche roles (i.e., metadata) in NAS and SAN environments. Figure 4. Data rate vs storage capacity for differing drive technologies or storage media 5
Concurrent connections (I/O streams). While similar to bandwidth, this is more of a consideration if you have a multitude of low bandwidth I/O streams. For example, a broadcast server that plays 12 streams of very low bandwidth compressed video. Technically, the speed of just two SATA drives will cover that requirement. But since there are so many streams hitting the drives, you need more disks in the group to handle all of the I/O. Without additional disks, the drives try to do too much and get almost nothing accomplished (a situation known as disk thrashing ). This is another place where SAS drives shine. Their higher rotational speed, dual-ported nature and lower latencies give you a much more gradual drop off when you start pushing them too hard. SATA, on the other hand, will handle a certain amount of I/Os, but if you push past that number, it drops off a virtual cliff, going from almost full performance to almost none. Tiering. While there are notable tradeoffs between speed and capacity, most broadcast and post-production teams need both. Many want SAS drives for their speed, but don t have the budget to buy enough of them to fulfill their overall capacity requirements. The answer is a tiered approach, utilizing a combination of storage technologies. For example, SAS drives for online volume, high capacity SATA drives for near-line volume and tape for offline volume. A tiered SAN will provide greater flexibility to fulfill bandwidth and capacity requirements, with the ability to move data between the different tiers. Figure 5. Example of a tiered or hybrid architecture. Summary The best storage solution for any given broadcast or post-production facility will depend on a number of factors, but for many, the decision will come down to cost vs. performance. NAS may be the better choice for teams with a limited budget that want to get up and running quickly and are willing to sacrifice speed. NAS is also an ideal option for archiving files that are infrequently accessed. For teams wanting a fast and smooth post-production process and the highest levels of broadcast performance, SAN will likely be the better choice. It delivers the speed required for accessing, manipulating and distributing HD and 4K files. It supports multi-system access for the synchronous, multifaceted nature of post-production. It comes with the redundancy and uptime needed for broadcasting. And it aligns with other parts of the storage infrastructure, providing the flexibility and cost-efficiency of a tiered environment. To discuss the best storage solution for your broadcast or post-production applications, contact the Rohde & Schwarz Broadcast and Multimedia Team at info@rsa.rohde-schwarz.com or go to www.rohde-schwarz-av.com. 6
Rohde & Schwarz Storage Solutions For the unique storage requirements of post-production and broadcast television workflows, Rohde & Schwarz offers reliable, high-performance storage technology for saving, managing, and archiving the enormous amounts of data associated with compressed and uncompressed content. Additionally, our software allows you to comfortably handle the most complex enterprise storage solutions and distributed data systems from a single point of management. SpycerBox Cell 30 hot-swappable drives (SSD, SATA or SAS) in a 1U chassis Supports uncompressed and compressed formats up to 8K Data rates up to 3 GB/s per module SpycerBox Flexible configurations for SAN, NAS, or hybrid storage systems High-speed, high-throughput SSD technology to serve hundreds of clients SpycerBox High Availability Option for mission-critical content integrity DVS-SAN Heterogeneous, modular infrastructures for maximum flexibility and efficiency Powerful storage performance with 30% less energy consumption and 25% less footprint compared to similar systems Multiple support levels available for customers, including mission-critical 24/7/365 coverage Want more information? Click here or Contact us. 7
About Rohde & Schwarz Rohde & Schwarz is an independent group of companies specializing in electronics. It is a leading supplier of solutions in the fields of test and measurement, broadcasting, radiomonitoring and radiolocation, as well as secure communications. Established nearly 80 years ago, Rohde & Schwarz has a global presence and a dedicated service network in over 70 countries. Company headquarters are in Munich, Germany. Environmental commitment Energy-efficient products Continuous improvement in environmental sustainability ISO 14001-certified environmental management system Regional contact USA & Canada USA: 1-888-TEST-RSA (1-888-837-8772) from outside USA: +1 410 910 7800 customersupport@rohde-schwarz.com East Asia +65 65 13 04 88 customersupport@rohde-schwarz.com Europe, Africa, Middle East +49 89 4129 123 45 customersupport@rohde-schwarz.com Rohde & Schwarz USA 6821 Benjamin Franklin Drive Columbia, MD 21046 888-837-8772 info@rohde-schwarz.com www.rohde-schwarz.com