The Fourth Dimension of Virtual Reality: Storage

Creating immersive experiences requires a reassessment of one’s storage environment. The technology used for producing virtual reality (VR) experiences is progressing rapidly. Just a few years ago, capturing video for VR involved bolting multiple cameras into an improvised housing to keep   the cameras aligned.

Since then, several technology companies have invented a range of solutions specifically designed for capturing 3D 360-degree video for VR. For example, a NextVR camera rig uses RED Epic Dragon cameras to capture video at up to 6K resolution.

GoPro, in conjunction with Google, created the Odyssey, which includes 16 cameras that capture 3D 360-degree video. The Facebook Surround 360 reference design uses 17 cameras. And 360 Designs produced the EYE camera with 42 Blackmagic Micro Cinema Cameras that capture 3D video across three axes.

As technology companies continue to innovate, they are introducing professional and consumer cameras that are smaller, less expensive, and easier to move around.

Cameras today offer in-camera image stitching and the flexibility to support a wide range of formats and data rates. The GoPro, Omni, Sphericam 2, Orah 4i, and 360fly 4K are already enabling a broader range of individuals and studios to cost-effectively produce high- quality 360-degree video and VR.

At the same time, demand for VR experiences is growing, supported by an influx of new consumer VR solutions and an expanding number of use cases. Consumers can purchase high-end VR systems, such as Oculus Rift, simply pair their smartphones with Google Cardboard, or even view 360-degree videos on Facebook and YouTube.

VR is being used not only for entertainment, sports, and gaming, but also technical training, sales, and marketing. Users can be transported to new worlds, experience courtside seats at a basketball championship, or explore virtual prototype product designs.

Is one’s studio moving into VR? If so, one’ll need more than a camera. Implementing the right storage solution must be a top priority. One need storage that can deliver the performance for capturing and working with multiple streams of 4K and higher-resolution video.

And one needs the capacity to store a fast- growing volume of large video files.

What is the right storage solution for one? Storage for VR is not one size fits all. Once one has a full grasp of the challenges of supporting VR content, one can use Quantum storage performance testing as a guide to find the right solution for one’s precise requirements.

Identifying The Storage Challenges Of VR

Innovations in VR camera technology are driving the need for significantly greater storage performance and capacity. The GoPro Odyssey captures 75 MB/sec of content while the NextVR captures 528 MB/ sec for its 6K video. The Facebook Surround 360 design captures 2 GB/sec, and the 360 Designs EYE captures 2.7 GB/sec—that’s the equivalent of capturing a DVD movie worth of data every two seconds.

The upward trend for capture data rates shows no sign of stopping. Uncompressed 5K stereoscopic video would record an astounding 7 GB/sec.

High data rates and large data volumes have implications for storage at every stage of VR production.

Capture

One needs storage performance that can ingest content in large high-resolution formats from multiple streams.

Preparation

Once we’ve ingested the video content, one’s team has to apply color correction and fix any stitching anomalies. One’ll need real-time performance to enable team members to complete these tasks swiftly and prepare the video content for editing.

Editing

As it is with video preparation, editing requires real-time performance. Editors can’t wait for clips to load or be delayed by sluggish performance. If multiple editors are working on the same files, one’ll need storage that can handle multiple streams of large high-resolution files.

Retention

Does one’s studio employ a “save everything” approach? If so, one’ll require tremendous storage capacity for VR projects. Keeping everything on primary storage is not cost effective - one’ll need a robust archive solution that allows one to free up space on primary storage without giving up visibility or accessibility of files.

Unfortunately, many existing storage solutions are not up to the task. In particular, those existing solutions can’t deliver the performance to accommodate numerous streams of large high-resolution files.

Are flash-based solid-state drives (SSDs) the answer? Not necessarily. While flash can deliver strong performance for many workflows, the higher cost and lower capacity of typical flash drives compared with hard disk drives (HDDs) means that one should carefully assess one’s requirements before investing.

Pinpointing The Primary Factors That Affect Performance and Capacity

There are several project and workflow factors that can define one’s performance and capacity requirements.

Data Rate

The resolution and frame rate one is working to play a critical role in determining one’s storage performance requirements.

Moving up from high definition (HD) to 4K, and from 30 fps to 60 fps, significantly increases the amount of capacity and the level of performance one need to support VR workflows.

Compressed vs Uncompressed Video

The decision to work with compressed or uncompressed video also affects one’s requirements. Working with uncompressed video can be advantageous for some important post-production tasks, such as color correction and high-end compositing, where accuracy is critical and glossy compression can produce less-than-stellar results. But if one decide to work with uncompressed raw media, one’ll need even greater performances and storage capacity.

Stream Count

The number of simultaneous streams one needs to support also plays an important role in one’s storage requirements. For example, simultaneously ingesting content from 42 cameras used for the 360 Designs EYE requires a different level of performance and capacity than ingesting content from the 17 cameras of the Facebook Surround 360 design platform.

Similarly, enabling several team members to conduct multi-stream editing could steer one to one type of drive rather than another.

Data rates and required capacity rise rapidly as resolution increases.

Defining Optimized Storage Configurations For Media and Entertainment Workloads

Quantum conducted extensive testing with real-world media and entertainment workloads to help determine ways to optimize storage for today’s and tomorrow’s post- production requirements.1 The testing — which led to the development of the Quantum SureStaQ 4K reference architectures — generated several important conclusions that are applicable to VR projects and workflows.

Testing

The Quantum team tested:

• Six 4K formats—including compressed and uncompressed formats
• Three drive types—SSDs, 2.5-inch HDDs, and 3.5-inch HDDs
• Five different Quantum storage arrays
• Two capacities (0% and 85% capacity)
• Three client operating systems—Linux, Mac, and Windows

Using a standard video, I/O performance tool calibrated for real-world applications, the team evaluated stream counts for Autodesk Flame and Blackmagic Design DaVinci

As part of the evaluation, the team also assessed performance relative to cost, highlighting the situations when incremental performance improvements provided by one type of drive might not be worth the extra investment.

Results

The testing for compressed media showed that flash-based SSDs are ideal for extremely high stream counts — as long as cost-effective capacity is not a priority. However, small form-factor 2.5-inch HDDs can support high stream counts at a significantly lower cost and with much greater capacity than SSDs.

By comparison, the large form-factor 3.5- inch HDDs did not perform as well with high stream counts. They can, however, provide a great value for low data rates, low stream counts, and uncompressed files.

For uncompressed media, overall, HDDs provide a much better value than SSDs.

The tests also yielded some interesting conclusions about the role of operating systems in media and entertainment workflows. Specifically, the team found that the Linux client could deliver 15% better performance compared with Mac and Windows clients. Both Mac and Windows were “chattier” operating systems, with greater CPU overhead that reduced performance.

Implications For VR

The Quantum testing, which focused on 4K content, provides a good basis for defining VR requirements. The output files for several VR viewers are essentially dual 4K images. One need storage that can handle capturing, manipulating, and delivering dual 4K video streams in real time.

More specifically, producing VR experiences requires:

• High capacity to handle a tremendous volume of high-resolution source material, especially if one is working on long-form projects.
• High performance to support potentially numerous streams during ingest and the post-production workflow.

Is flash the right solution for VR? Short- format VR projects can definitely benefit from flash-based SSDs. But given the higher cost of flash drives, they are probably not the best choice for long-form projects. Until flash drive prices fall, small form-factor HDDs can deliver the right mix of compressed multi- stream performance and high capacity for many VR projects.

Preparing For Growth

Incorporating an archive can help free up primary storage.

As one selects a storage solution for VR, scalability should be an important consideration. The size of VR projects will keep growing as technology companies continue to produce innovative new solutions for capturing and playing back 3D 360-degree video.

One’s VR solution should enable one to scale out as well as scale up. Scale-up solutions allow one to add disk arrays to an existing controller. But at some point, one will reach a maximum capacity with too many disks saturating the controller and limiting performance.

With scale-out solutions, one can increase performance along with capacity by adding a controller with each expansion storage box. With the right solution, one can continue this approach to scaling without limits.

One should also consider incorporating an archive solution into one’s environment to help accommodate growth while optimizing utilization of the primary storage system. High-performance primary storage can be expensive— especially if one use flash. Although one’s studio might want to save everything, it will be increasingly difficult to store every version of every file on primary storage.

An archive solution will let one offload some of one’s less frequently used files, such as older versions of files, to a more cost-effective environment. Whether one opt for object storage, tape, or cloud storage, the right archive solution will enable one to maintain the visibility and accessibility one need, so one’s team members can access archived files quickly and easily. In addition, the right archive solution will be easy to integrate into one’s workflow. One’s team members should be able to move files to and from an archive without having to interrupt their work.

By Jim Simon, Vice President of Global Field and Channel Marketing, Quantum Corp