The following is the first in a series of blog posts from members of the Avid storage team discussing how ISIS shared storage overcomes challenges in an era where media is created and consumed everywhere.
Talking to Avid ISIS customers is one of the most enjoyable parts of my job. Not only do I hear about the cool projects they are working on, I frequently get to hear how much they appreciate their ISIS storage systems. The conversation frequently goes something like this:
Customer: “I love my ISIS. It just works.”
Me: “Thank you. Do you have other storage systems you use for media editing?”
Customer: “I did, but I couldn’t wait to retire it. I spent entirely too much time running around trying to fix problems and keep my editors happy.”
Even though our customers know that ISIS works great for real-time editing, they don’t necessarily know why or how it works. All they care is that it meets their needs. For collaborative environments using networked media storage for video editing, there are five required capabilities. When combined, these requirements create a workload on storage systems that is unique to media editing. If your storage system wasn’t designed with these requirements in mind, there is a good chance it will stutter and fade when you need it to perform the most.
Multiple clients
Collaborative editing environments, by definition, consist of multiple editors. Even small shops with only a few editors have numerous media applications running on several different workstations. Media storage systems must be able to playback media streams reliably even as the number of clients accessing the media scales up or down.
Simultaneous Streams
The number of video streams being served by a storage system can grow, shrink and burst dramatically over short periods of time. In addition, streaming media presents a drastically different workload to a storage system.
Most traditional IT applications work best with storage that is tuned to deliver raw bandwidth and a high number of transactions per second. As a result, a storage system’s IOPS (IOs Per Second) rating is interesting to IT architects that design enterprise infrastructure. This rating is useless when designing media production infrastructure.
If you can’t find detailed information on a storage system’s supported stream counts for the type of media you are using, you will have to guess whether your workflow will work now as well as in the future. Take multiple streams and multiply by 10s or 100s of editors and the number of streams being served by a storage system can quickly scale beyond the capabilities of non-media optimized storage systems.
High Bandwidths
We all know and have to work with the myriad of available codecs out there. If you are not already working with 2k, 4k, 8k, 60 fps, 120 fps, stereoscopic and raw workflows, you are probably at least thinking about them. So not only does your storage need to support multiple editors and multiple simultaneous streams, it also has to deliver media formats that range from megabits per second all the way up to gigabits per second per stream.
Predictable Latencies
There are storage systems available with sub-millisecond latencies. But here is a frequently overlooked fact. Real-time editing does not require ultra-low latencies. At 24 frames per second, a storage system needs to deliver a frame’s worth of data every 40 milliseconds.
With clients, network and storage systems that use media-optimized buffering, predictable latencies of less than 300 milliseconds will typically provide smooth playback of video. Storage systems with shorter latencies are fine, but you may be paying for performance that you do not need. Storage solutions with longer latencies that lack media-optimized caching mechanisms will cause a degraded experience.
Fragmented Files
If it isn’t a big enough challenge for a storage system to deal with tight latency requirements for multiple clients accessing multiple high bandwidth media streams, lets not forget about fragmented files. Over time, as files are added and deleted to the storage system, they become fragmented. Some file systems attempt various forms of file defragmentation, but as the file system becomes full, fragmentation becomes inevitable.
When files are fragmented, the disk subsystem spends a lot of time moving from fragment to fragment and performance decreases. Testing a freshly installed storage system that does not have a mechanism to address file fragmentation will deliver greatly misleading results.
For reliable real-time media editing, it is important to understand how the file system deals with disk fragmentation and what the performance of the system will look like once the inevitable fragmentation occurs.
If your storage system talks only about IOPS, bandwidths and latencies, with no mention of supported stream counts, you are probably looking at a storage system designed for enterprise IT applications; not real-time media editing.
As you can tell, storage systems used for media playback have to work in environments that have unique requirements that do not align with typical IT application environments. One way to make sure your system will work for your requirements is to look for detailed information on supported stream counts and formats. If your storage system talks only about IOPS, bandwidths and latencies, you are probably looking at a storage system designed for enterprise IT applications; not real-time media editing.
Stay tuned, and in the mean time, if you find yourself at IBC in Amsterdam from September 13th – 17th, make sure to stop by the Avid booth (Hall 7, Stand J20) where you can hear for yourself how John Rogerson (CEO of HALO Post Production) as well as Andy Beale and Jamie Hindhaugh (Chief Engineer and COO at BT Sport) use Avid ISIS storage to deliver inspiring content.
If you can’t make it to IBC, but would like more info on ISIS shared storage, be sure to get in touch here.
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