July 21, 2017 at 1:11PM


Is this fast enough for 4K?


My new 2017 5K iMac is arriving in a few days and I need help figuring out what external hard drive setup I am going to use. Being fairly new to video, I need help.

I will keep my current projects footage on an external drive that connects through iMac's T3 port. I would need something that can handle 4K.

Things I am considering but don't know if they're fast enough to handle most 4K projects:

OWC Dual RAID enclosure (T2 / 474MB/s) - https://eshop.macsales.com/shop/Thunderbolt/External-Drive/OWC/Elite-Dua...

G-Tech RAID (T3 / 500MB/s) - http://www.g-technology.com/products/g-raid-tb3

G-Tech single drive (T3 226MB/s / single 7200 hard drive) - https://www.amazon.com/gp/product/B071DQR3FY

LaCie d2 (T3 240MB/s / single 7200 hard drive) - https://www.amazon.com/gp/product/B06XYDL5CP

The price is important, so if I can get away without a RAID system, I'd like to do that. If not, then I'd like to know if G-tech RAID is sufficiently fast.

Thanks you!


It all depends on how compressed your media is. if it's very compressed you can use a slower drive

On consumer drives they typically advertise the fastest they can deliver data, as opposed as to how fast they can deliver a sustained transfer. Your best bet is to buy the fastest you can get and hope as it fills up it stays fast enough.

July 21, 2017 at 5:35PM


To be more specific than Joseph, look at the ProRes spec from Apple:


This tells you exactly what disk bandwidth you need per 4K stream, if you are using ProRes. Other file formats have other, well-defined 4K codec bandwidth rates.

Secondly, as Joseph mentions, spinning disks transfer rates slow down as they fill up past about 50% capacity. So your disk performance is a moving target. SSDs don't suffer from that problem, and are great solutions for your working disks (not archives) if you can fit everything into a terabyte or less. (They get much more expensive once you pass the 1TB limit.)

July 23, 2017 at 6:56AM


Thanks to both of you.

I understand that there are many variables here and giving a definitive answer is often impossible. Being relatively new to this, I am struggling to understand all of this.

But, let me know if the following statement is generally true:

Using a RAID configuration with 2 enterprise level 7200 drives connected to an iMac with Thunderbolt 2

....is faster than....

a single enterprise level 7200 drive connected via Thunderbolt 3.

My reasoning here? T3 is faster than T2, but data stripped over 2 drives (RAID) makes things faster. Right?

Thanks again!

July 24, 2017 at 3:29PM

Alan Ford

i think you probably need a 3 drive striped raid (raid 5) for future proofing, external raid controller and upgrade the imacs ram, then you can handle 4k raw workflow.... ultimately the imac will be the bottle neck in terms of future upgrades... go with a an HP Z if you are serious

July 25, 2017 at 4:49AM, Edited July 25, 4:56AM

Matt Lovell

I'll have 40GB of RAM in the iMac. As for the HP, we're a team of two people and everything we run is Apple, has been for a decade for me and two decades for my partner, so going to Windows simply isn't an option. Damn this is hard when you're on the budget ;-).
Thanks to all.

Alan Ford

July 25, 2017 at 11:41AM

Here are a few high-speed external storage options:

AKiTiO Thunder3 Quad Mini

AKiTiO Thunder3 PCIe SSD

July 25, 2017 at 2:09PM

Glenn Bossik

I'm going to just go over the concept of this not your specific situation. Hopefully I will explain it well enough that you can use the info down the road.

There are a lot of factors going into disk speeds when reading footage off of drives, but I will keep it simple. First is how the drive is connected. If you are on an iMac then I assume it's going to be using Thunderbolt. So with TB3 you have 40 GB/s read and writes by the specs, the next hurtle will be how the drives are connected in the enclosure. The speed of this will most likely be 6 GB/s. Last limiting factor is the drive's speed. As already stated above spinning disk drive speeds are variable by where the data is on the disk and if it's random or sequential. Regardless the listed drive speeds are pretty close and I've found that 100MB/s is pretty average across the whole of most 7200 RPM Consumer drives.

All the techno babble aside, any multi drive enclosure with 4 or more drives running in RAID 5 or would give you roughly enough speed to meet read data rates of RED Raw 8k footage as long as the drives are 7200 RPM drives. So any of your cameras like GH4/5, FS7/5, C300 Mk II, etc. are going to give you much lower data rates. You should be fine for 95% of 4k footage coming from popular cameras today.

Getting to your drives listed in the post. Those should work as well as the drives used will be of high quality. They will have faster than average reads and writes. I would urge however that you get another drive to put this data on as a backup or use a RAID 5 enclosure. In the drives you have listed even if one of the two internal drives fails you will lose ALL YOUR DATA. RAID 0 setups are high risk/high reward type of scenario, so use caution when you have them in play.

With whatever route you choose to go I believe you will be fine as long as you aren't shooting in a Raw format. Good luck with your project and please feel free to ask if you have more questions or if I just made things confusing.

July 25, 2017 at 6:40PM

Kyle Acker
Cinematographer/ Video Editor


Can't thank you enough for your reply. Seriously. You wrote it the way I needed it to be said so I would truly understand it.

As for the backup, most people who know me and have some basic understanding of why you should backup things think that I am paranoid and insane. That's how seriously I take backup. Multiple copies on site and multiple copies offsite, + 2 online backups. For several years I kept one offsite backup on the other US coast. That I no longer practice, but I am sending a copy of everything to Europe this summer. Not that my stuff has such value to others, but it certainly has an enormous value to me.

Thanks again!

Alan Ford

July 26, 2017 at 11:54AM

I just ordered the G-Tech single drive listed above so I hope I'll be OK. This will be fine for my current needs I am sure, and if there is need for something faster and better, well, that job will or should have money in it to pay for an upgrade ;-).

Thanks to everyone.

July 27, 2017 at 3:21PM

Alan Ford

Your Comment