What spec on a hard drive determines to smooth playback in editor?

[David Roth weiss]

[Roger Alexander] “Can someone she some light on this? Also reccomendations on drives that are good in that spec to improve my playback?
“

Roger,

In looking back at some of your previous posts I see you’ve been struggling with this subject for quite a while, so let me clarify things for you. The following is an excerpt from a series of Cow articles I’m now writing on this subject.

The most important aspect about hard drive subsystems (RAID) that editors at every level need to wrap their heads around is “data throughput” — i.e. how much data per second can your media drive(s) reliably move to and from the CPU on reads and writes to disk at a sustained rate. Sustained data throughput for video applications is affected by a number of different variables that affect the overall performance of every NLE. (***Since the most important aspect of video editing is seamless playback of video files without dropping frames, it’s the read speeds that are most important in this discussion.)

What are the most important variables that affect the sustained throughput of a hard drive subsystem?

#1. The number of disks striped together in a RAID – a simple rule of thumb is, overtime you double the number of spinning disks you double the throughput approximately. So, 2-drives striped together in a RAID will generate approx. 2X the throughput of a single hard drive.

#2. Rated drive performance and RPMs of individual disks – older drives were rated at 1.5Gbit/sec, then 3Gbit/sec, and now we’re up to 6Gbit/sec drives. So, the drives themselves are now faster than before. (***7200RPM spinning drives drives are the standard for video editing applications because of price and performance, 5400RPM drives are too slow, 15,000RPM drives are too expensive, and SSD drives are also too expensive)

#3. Connection speeds – various connections have different max throughput ratings in this order: USB2, Firewire 400, Firewire 800, USB3, SAS 6G, Thunderbolt 1, and Thunderbolt 2. (***for our purposes consider SAS 6G and Thunderbolt to be approximately identical in terms of throughput)

#4. Video Bitrates rated in MB/sec – i.e. how many megabytes per second is required to play a single stream of a specific video codec (***4K varies significantly from uncompressed down to highly compressed proxies)

#5. Total number of simultaneous streams – i.e. how many streams of both audio and video at specific bitrates are to be played back at the same time (***streams of video equal layers – if you stack six layers of video and change the position or opacity of each, that equals six streams – if you stack six layers and only view the top track, that’s only one stream)

#6. Misc computer components – CPU speed, Bus speed, RAM speed and amount, Controller card speed, etc. (***all of these also play a role in the overall performance of your NLE and they impact the throughput of data to and from the hard drive subsystem.)

Determining the necessary specs of a RAID for seamless playback of 4K is not rocket science, but it is science nonetheless, and it first requires that you specify the variables mentioned in #3 thru #6 above. (***When specifying the video codec, always consider the predominant video codec you’re editing now, while always keeping an eye toward the future, because video files will only get larger and more demanding.)

If you’d like me to help you with the science to determine the best RAID solution(s) for your needs, please email me privately at drw@drwfilms dot com and I’ll be happy to help you. In addition, I consult with a number of different resellers, and I can offer you pricing that will meet or beat the best online deals you can find.

I hope this proves helpful to you and others here on the Cow.

David Roth Weiss
Director/Editor/Colorist & Workflow Consultant
David Weiss Productions
Los Angeles

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[Roger Alexander]

David this is the best response I have ever received from anyone on a forum. Thank you for the time on this. I will definitely email you for recommendations from alphamalevisuals@gmail dot com

[David Roth weiss]

[Roger Alexander] “David this is the best response I have ever received from anyone on a forum. Thank you for the time on this.”

Thank you Roger! I’m blushing now…

I’m always happy to help here and to share the knowledge I’ve been lucky enough to acquire as a user, equipment sales exec, and consultant.

Meanwhile, I received your email and I’ll contact you shortly to discuss your needs and my recommended solution(s).

David Roth Weiss
Director/Editor/Colorist & Workflow Consultant
David Weiss Productions
Los Angeles

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.