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Their technical details page seems to push eMMC pretty hard but their prices, 64GB for $80 [1], seem really high compared to a microSD card. Can anyone with exp

Their technical details page seems to push eMMC pretty hard but their prices, 64GB for $80 [1], seem really high compared to a microSD card. Can anyone with experience comment on whether the eMMC has anywhere near the value for its price? [1] http://hardkernel.com/main/products/prdt_info.php?g_code=G141628557245 http://hardkernel.com/main/products/prdt_info.php?g_code=G14...

simlevesque 12y ago
I bought a Odroid-U3 and pretty often the bottleneck was on the microSD card so I grew tired of it and I bought a eMMC 64gb and it gets the job done. It is way faster than the best microSD if that is what you were wondering.
tankenmate 12y ago
Some eMMC modules claim 150MB/s read/write; i.e. same speed as hard drives from about 5-7 years ago. Or put another way approximately twice as fast as an average USB3 flash drive.
- beagle3 12y ago
  You had a 150MB/s hard drive 5 years ago? What kind of a drive was that? I'm only getting 100-150MB/sec on rotating media today. Only 7.2K, but even 5 years ago, 10K didn't deliver that transfer speed from what I remember.
  - desdiv 12y ago
    He was probably referring to solid state hard drives.
  - vardump 12y ago
    For example 1TB Samsung drives delivered 100 MB/s over 5 years ago. Most 3.5" disks delivered as much.
    - beagle3 12y ago
      I was surprised by that, though I shouldn't have been: I'm getting about 100MB/sec from 3.5" Samsungs, WDs and Seagates today - but you're right according to these 4 year old benchmarks: http://www.storagereview.com/western_digital_caviar_blue_1tb_review_wd10ealx http://www.storagereview.com/western_digital_caviar_blue_1tb... I guess the configuration I'm benchmarking with, and the type of load, which is basically streaming, but from a journaled-but-otherwise-standard ext4, slows me down a little. But the convenience and standardness of this setup is worth more to me than a factor of 2 in performance (that's not my bottleneck at the moment).
monocasa 12y ago
Yes, it does. SD cards are not really designed for being used as a root file system. They are OK at streaming writes and reads, but once you start getting non sequential they slow down like you wouldn't believe. Which, yes, I know, is super weird for what should just be some glue logic around a NAND. I was investigating corruption and performance problems with our root filesystem on an SD card. The cards would be great a obvious benchmark style tasks, but when I recorded the block access pattern from our driver and replayed that on a Linux desktop with O_DIRECT, we'd not only get under 200KiB/s average access speed (which matched what we were seeing on the embedded system), but we would also get corrupted sectors (ie. we write it just fine, but we just get an error back from the card when we go to read the sector) in less than a day of sustained writes (once again at only 200KiB/s). And this was with high quality SanDisk cards that were then verified by them to be real cards (for a while we thought that clones had made their way into our supply chain). Using a weird form factor eMMC chip in an SD card got rid of these issues. There's also "industrial" SD cards that are around the same price that I suspect are basically the same thing.
- kragen 12y ago
  Most SD and μSD cards have embedded microcontrollers http://www.bunniestudios.com/blog/?p=3554 http://www.bunniestudios.com/blog/?p=3554 — I wonder how much of the corrupted-sector problems you were getting are really just bugs in their firmware? Or things that could be worked around with better firmware?
  - monocasa 12y ago
    Yeah, it was almost certainly firmware bugs combined with already marginal NANDs. ie. the NANDs probably would have been fine if they were babysat a little better, but they were probably bottom of the barrel. That's kind of the SD card market in a nut shell any way. That being said we tried many different SD cards from quality vendors and found pretty heavy bugs and performance related issues among all of the non "industrial" versions. So, yes, the problems don't have to be intrinsic to the form factor, but empirically you're more likely than not to have issues with them.
hardwaresofton 12y ago
EMMC is worth it, I have the ODroid U2 and am about to purchase the one at this link, and would not skip out on the EMMC for anything. SD card bottleneck is real.
ansible 12y ago
With eMMC you can have an 8-bit data bus (instead of 4) and higher clock speed.

simlevesque 12y ago

I bought a Odroid-U3 and pretty often the bottleneck was on the microSD card so I grew tired of it and I bought a eMMC 64gb and it gets the job done. It is way faster than the best microSD if that is what you were wondering.

tankenmate 12y ago

Some eMMC modules claim 150MB/s read/write; i.e. same speed as hard drives from about 5-7 years ago. Or put another way approximately twice as fast as an average USB3 flash drive.

beagle3 12y ago
You had a 150MB/s hard drive 5 years ago? What kind of a drive was that? I'm only getting 100-150MB/sec on rotating media today. Only 7.2K, but even 5 years ago, 10K didn't deliver that transfer speed from what I remember.
- desdiv 12y ago
  He was probably referring to solid state hard drives.
- vardump 12y ago
  For example 1TB Samsung drives delivered 100 MB/s over 5 years ago. Most 3.5" disks delivered as much.
  - beagle3 12y ago
    I was surprised by that, though I shouldn't have been: I'm getting about 100MB/sec from 3.5" Samsungs, WDs and Seagates today - but you're right according to these 4 year old benchmarks: http://www.storagereview.com/western_digital_caviar_blue_1tb_review_wd10ealx http://www.storagereview.com/western_digital_caviar_blue_1tb... I guess the configuration I'm benchmarking with, and the type of load, which is basically streaming, but from a journaled-but-otherwise-standard ext4, slows me down a little. But the convenience and standardness of this setup is worth more to me than a factor of 2 in performance (that's not my bottleneck at the moment).

monocasa 12y ago

Yes, it does. SD cards are not really designed for being used as a root file system. They are OK at streaming writes and reads, but once you start getting non sequential they slow down like you wouldn't believe. Which, yes, I know, is super weird for what should just be some glue logic around a NAND. I was investigating corruption and performance problems with our root filesystem on an SD card. The cards would be great a obvious benchmark style tasks, but when I recorded the block access pattern from our driver and replayed that on a Linux desktop with O_DIRECT, we'd not only get under 200KiB/s average access speed (which matched what we were seeing on the embedded system), but we would also get corrupted sectors (ie. we write it just fine, but we just get an error back from the card when we go to read the sector) in less than a day of sustained writes (once again at only 200KiB/s). And this was with high quality SanDisk cards that were then verified by them to be real cards (for a while we thought that clones had made their way into our supply chain). Using a weird form factor eMMC chip in an SD card got rid of these issues. There's also "industrial" SD cards that are around the same price that I suspect are basically the same thing.

kragen 12y ago
Most SD and μSD cards have embedded microcontrollers http://www.bunniestudios.com/blog/?p=3554 http://www.bunniestudios.com/blog/?p=3554 — I wonder how much of the corrupted-sector problems you were getting are really just bugs in their firmware? Or things that could be worked around with better firmware?
- monocasa 12y ago
  Yeah, it was almost certainly firmware bugs combined with already marginal NANDs. ie. the NANDs probably would have been fine if they were babysat a little better, but they were probably bottom of the barrel. That's kind of the SD card market in a nut shell any way. That being said we tried many different SD cards from quality vendors and found pretty heavy bugs and performance related issues among all of the non "industrial" versions. So, yes, the problems don't have to be intrinsic to the form factor, but empirically you're more likely than not to have issues with them.

hardwaresofton 12y ago

EMMC is worth it, I have the ODroid U2 and am about to purchase the one at this link, and would not skip out on the EMMC for anything. SD card bottleneck is real.

ansible 12y ago

With eMMC you can have an 8-bit data bus (instead of 4) and higher clock speed.