The D16’s Media Core

There are a few hardware components that immediately come to mind when one thinks about what determines image quality of any particular camera. One thinks about the sensor, the lenses, maybe even the analog to digital converters, but you rarely think about the storage device, even though it’s of the most important factors.

Pile-Of-Memory-Cards

The storage device is often the bottle neck for your data throughput. The stability of the storage device not only reflects on the reliability of the camera, but sometimes can effects image quality. When bits are written incorrectly it can look like noise, artifacts, even dropped frames. When talking about SSD drives specifically, there is a whole separate class of drives which are designed and tested to be much more robust than typical drives and avoid these and other issues. They are called “enterprise” class drives.

Enterprise class drives are built from better materials, are much faster than normal drives, and are much more reliable. They are more reliable because they have enterprise data path protection which is a combination of hardware and software that determines the logic path your data actually takes while being written to the drive, and how it’s read later.

This is an example showing the difference in complexity between a typical drive and an enterprise class drive:

Data Path Protection DiagramYou can see that the complexity of enterprise drives is much higher. The firmware is also tuned for high end use. This means that your precious bits are checked and double checked as they are being written and read to assure that there are no errors, and if there are, the errors are corrected.

If we are taking care to create the best looking images we can we must also take care to store them correctly once the images are created.

When we were picking a drive for the D16 we had many factors to think about. Reliability and speed were most important, but price had to be part of it too. These enterprise drives are not cheap. When Arri charges over $3000 for a 512GB mag it’s because the drive inside costs almost $2000 in the first place. Until recently, you had a lot of choices in SSD brands and models, but not a lot of choices in SSD Class. You had the consumer level drives around $120 – $400, and you had your enterprise level drives that were between $480 – $2000. At that time putting an enterprise class drive inside a camera like ours would have been out of the question. Either the drive would be too small to be useful or the drive would cost the equivalence of half the camera price.

These days there are mid level drives, which are perfect for our camera. The drives are priced between the other two classes, they have the kind of performance and protection we want for our camera, including enterprise data path protection, and are being made by reputable companies.

 The drive we have selected is the 400GB Micron P400e, an upgrade from our previously announced spec of 256GB internal drive. This drive is on the lower price side of enterprise class drives, but has middle of the market performance. It is also the drive with the lowest power consumption after startup, and one of the lowest heat indexes.
micron_p400e

There is even a slim version of the drive that is only 7mm tall instead of the standard 9.5mm.

The actual drive capacity of the hardware is 512GB, but it has been reduced to 400GB to create buffer space for dynamic wear leveling, meaning that the drive lasts much longer by allowing space for bad sectors over long periods of time. The P400e also has power-loss protection, meaning that if the camera power cuts out suddenly the drives’ onboard capacitors store enough power for the drive to commit all pending write commands before turning off.

But what about lifespan? There are not spec tables setup for our use case, which is very different from normal SSD use. First of all, most SSD use is rated for random read and write, and our use is almost completely sequential read and write. Also the published specs are for 1 year of data retention, which assumes you won’t erase any particular piece of data for 1 year. There is a direct inverse relationship between data retention and life span. So, for instance, if you lower the data retention to one day instead of one year the estimated life cycles go up dramatically. It took a little bit of work, but we estimated the drive life with our Micron dealer and it came out like this: the drive is rated for 1.2 million device hours and with our use case we think it will last at least 5,000 full write cycles before showing any kind of data loss, which means if you wrote the full capacity of the drive 3 times a day (4 hours of raw recording), every single day, it would last over 4 and half years! Most of us won’t shoot 240 minutes of footage in a day, and we won’t shoot every day either, so we estimate the drive will last somewhere between 5 and 10 years even with regular use.

We think reliability and data accuracy are very important parts of any camera, and we believe the Micron P400e will help us make a camera with these attributes.

Thanks for reading, Joe and the Digital Bolex Team

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joerubinstein

About joerubinstein

Joe Rubinstein is one of the founders and CEO of Digital Bolex. At Polite in Public, a photo marketing company he also co-founded, Joe was the Chief Technology Officer who worked with electronics developers and software developers to create the Polite in Public Photobooth which helped define modern photo marketing services.

21 thoughts on “The D16’s Media Core

  1. Pingback: Digital Bolex: The D16′s Media Core, by Joe Rubinstein | digital-cinema-tools.com

  2. Most informative. The more we know the more we like it. The more we like it the more we want it. The more we want it the more our significant others get tired of hearing us talk about it. The less we talk about it, the more we want it.

  3. Amazing! I never new ssd drives could affect quality! this camera will rise above the rest. I love how every detail is well thought out. Not only that potential clients become well educated from your posts unlike most companies. i cant wait for this system but i will! as long as it takes!

  4. One more thing. I guess it’s a little late for input on the design process and I know that this has been discussed at the time quite extensively but in retrospect wouldn’t it have been wiser to get rid of the CF card slots entirely by incorporating a SSD slot? Giving us the chance to swop a limited amount of preselected SSD’s?

    • The time, thought, and money being put into the internal drive is exactly why we don’t want to make a removable SSD option.
      As stated above normal SSDs don’t have the error protection or physical design for hot swapping.
      If you read any of the manuals that come with SSD drives they tell you these drives are vulnerable to static shocks and power spikes like when plugging or unplugging a drive. CF cards are by contrast designed specifically for this kind of use.
      I strongly believe that in the future we will look back at hot swappable SSD as weird in between stage between CF card and what ever comes next.

  5. Hey Joe,
    thanks for the update. I got a couple of question for you. You wrote:
    “if you wrote the full capacity of the drive 3 times a day (4 hours of raw recording), every single day, it would last over 4 and half years! Most of us won’t shoot 240 minutes of footage in a day” …

    Based on this calculation we would be able to record around 80 minutes per 400GB. I used KataData from Katabatic Digitals to calculate the recording time which gave me roughly 28 minutes in 2K 16:9 (2048 by 1152) at 24 fps in 12bit Cinema DNG. Could you please explain your calculation in more detail? Will we be able to select and playback clips internally from the camera? And if so are we able to delete takes on the fly?

    I noticed that the new D16 Spec Sheet PDF doesn’t list a 2.5K recording mode anymore. How come?

    Any news on enabling the camera to record with a base setting of 800 ISO yet?

    All the best to you and the D16 Team,
    Yves Roy

    • Hi Yves,
      I don’t know where the calculations for KataData come from, but I’ll break down our calculations for you.
      The 2K Cinema DNG files from the D16 are 3.5 megs per frame, which is 84 megs per second, 5 gigs per minute, and 300 gigs per hour.
      Playback will be available in camera, and deleting takes should be possible too.
      2.5K or full sensor record mode will be released when we release anamorphic mode.
      No news yet on 800 ISO, it will take a lot of testing once we have everything else working 100%.

      • Thanks for clarifying. Makes sense. ;-]
        I double checked and I can’t find a clear explanation on how KataData calculates the recording time other than what I’ve stated in my earlier post. They’ve just added a BMCC preset though which results in roughly one hour recording time based on 2.5K/24p in 12-bit Raw.
        The data generated from the audio recordings might be considered for an more accurate equation. Anyway, thanks for getting back to me!

    • Hey Yves! Just about the spec sheet: the original spec didn’t have that 2.5K mode either because the spec sheet is (currently) what’s planned to be included on launch. I think enabling the full sensor mode will come with a firmware update.

  6. This is a field in which I know little about. But it is very impressive to see the amount of thought and consideration that is going into the whole process. Really excellent, in my opinion.

  7. Nice post and nice info about the drive, thanks!
    Now we need some post about the overall process, cause the latest I saw about that was some, sorry, but murmuring on the forum “our engineers were thinking it would be easier and faster”. Oh come on, like faster than one year?

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