Sony 64 GB MicroSDXC Card: Speed Failure Redux

After about 1 TB of data spread over three months and maybe 100 bike rides, the second Sony SR-64UY 64 GB MicroSDXC card I bought last summer has failed… barely two weeks inside the one year warranty.

As with the first card, this one works fine except for the speed: it cannot record at 1920x1080p @ 60 fps. The only indication comes from aiming another camera at the display to capture the failure as it happens.

Just before the failure:

HDR-AS30V - MicroSDXC failure - 1

HDR-AS30V – MicroSDXC failure – 1

It’s taking stock of the situation:

HDR-AS30V - MicroSDXC failure - 2

HDR-AS30V – MicroSDXC failure – 2

Presumably, it’s patching up the abruptly terminated file:

HDR-AS30V - MicroSDXC failure - 3

HDR-AS30V – MicroSDXC failure – 3

Another box is on its way to Sony Media Services…

Over the last year, the price of an almost certainly genuine Sony SR-64UY Class 10 UHS-1 MicroSDXC card has dropped by 2.2 dB: $40 to $24. Now, however, the SR-64UY is the “old model”, so you can pay $30 (-1.3 dB) for an SR-64UY2 rated at 70 MB/s transfer speed (up from 40 MB/s), albeit with no change in the card’s speed class.


Both cards failed after writing 1 TB of data (give or take maybe 20%) in 4 GB chunks over the course of 100 recording sessions. The cards still work, in the sense that they can store and accurately retrieve data, just not at the Class 4 (not Class 10) speed rating required by the HDR-AS30V at 1920x1080p @ 60 fps.

The table in the Wikipedia Secure Digital article says Class 4 = 4 MB/s, which is slightly faster than the camera produces 4 GB files in 22:43 min:sec = 3 MB/s. A Class 10 card should write at a sustained 10 MB/s, so the SR-64UY write speed has dropped by at least a factor of 3 from the spec. I’d expect the root problem to be the error correction / block remapping / spare pool handling time has grown as the number of failed blocks eats into the card’s overcapacity, but I have no inside information.

When the replacements slow down, I’ll see how they work as Raspberry Pi memory…


  1. #1 by bonnev659 on 2015-07-10 - 08:24

    that is a major bummer, what other brands have you been using? sandisk? samsung?

    • #2 by Ed on 2015-07-10 - 08:49

      Basically, I bought two Sony cards, stuck one in the camera, used it until it failed, and now I’m using the second one, with the first replacement waiting its turn. I extract the video files through the USB port to avoid fat-fingering the MicroSD card back into its slot.

      It’ll be interesting to see how long the Kingston 8 GB Class 10 / U1 card that came with the Fly6 survives under the same exercise regimen.

      Which is a long way of saying I don’t have any comparative results with other cards under the same conditions.

      If I weren’t so fixated on capturing video at the camera’s maximum resolution and highest speed, the Sony cards would still work, but that’s definitely cold comfort.

  2. #3 by david on 2015-07-10 - 21:31

    Interestingly, it turns out that ‘Class x’ doesn’t actually guarantee X-mbps write performance except when the card is empty! See p.84-85 of this doc (labelled as p96-97 in the pdf):

    • #4 by Ed on 2015-07-11 - 08:09

      I didn’t know that, but, somehow, I’m not surprised that the “speed rating” doesn’t really mean very much. Given that I copy-and-delete the AS30V files after every ride, the card always starts nearly empty, never gets more than maybe 1/4 full, and still fails after just a few minutes from a cold start.

      In contrast, Cycliq recommends never deleting any files and letting the Fly6 manage the FAT filesystem: it discards a 500-ish MB file whenever it needs more space, so the card always runs nearly full. On the other paw, the Fly6 writes data at 500 MB/10 min = 0.83 MB/s, so it should work with nearly any card, even though they specify Class 10.

      Thanks for the pointer!

    • #5 by madbodger on 2015-07-19 - 09:51

      That is interesting. I have a camera that can shoot 1200fps flat out, and the instructions for it insist in a “class 10” card, which was a bit of a rare bird when the camera first came out. Seems to work okay, however.

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