128GB microSDXC card on Cubietruck

hiroshi · July 3, 2016

I'm thinking of getting a 128GB microSDXC card (Samsung EVO) for my Cubietruck. Is this likely to work or is 64GB a hard limit?

Of course, I intend to put a sane filesystem on it, like ext4.

Igor · July 3, 2016

It should work, but:

- performances of those cards are terrible especially for system usage (Samsung EVO+)

- it cost around 50 eur and for this you can get a proper SSD SATA drive with the same capacity and up to 50x better speed. Not to mention higher reliability.

hiroshi · July 3, 2016

Well, it was my impression (from this thread) that the Samsung EVOs were among the better (and more affordable) microSDXC cards for SBC purposes... and I need the SATA port for a 1TB (mechanical) hard drive that would otherwise sit here unused.

As a consequence of using a hard drive, it is preferable to have separate media (one for reading and one for writing) when unpacking files, such as Usenet downloads, which will be one of the applications for my Cubietruck. The microSDXC card would be used for storing packed files before they're unpacked to the hard drive.

Admittedly, a single 1TB SSD would do the job better than the microSDXC card + hard drive combination, but SSDs of that size are still too expensive, comparatively, and I have the hard drive already.

Eventually, I want to run the OS from NAND but mainline support does not seem to be there quite yet. When mainline (and armbian!) NAND support improves sufficiently, then I'll move the OS to NAND and use the microSDXC card exclusively for downloads, as described. In this case the microSDXC card will be accessed mostly sequentially.

I've also considered using a USB stick instead of the microSDXC card. Once I can run the OS from NAND, is there any reason to prefer a microSDXC card to a USB stick, at least for my described application?

Igor · July 3, 2016

Samsung EVO and EVO+ are good in 16,32 and 64GB package, while 128GB perform slower. Don't know why but I found similar tests around on the net to confirm mine. Card looks genuine and it was brand new while running a test.

NAND is slower than most SD cards you'll find around, except cheapest ... if I do some average estimation. But if NAND is enough in size (8GB), than 32GB should already be enough? 32GB Samsung EVO is currently one of best price / performance SD card.

Alternatively, check boards with eMMC, Orange pi PC+ (faster cpu, sata via usb) or Olimex Lime 2 eMMC (build in sata and batery backup).

hiroshi · July 3, 2016

8GB is enough for the OS, but not enough for my Usenet downloads, which require, in addition to the 1TB hard drive, a separate medium, around 128GB in size.

Anyway, since USB sticks are cheaper than microSDXC cards, is there any reason to prefer a microSDXC card to a USB stick?

The Cubietruck still seems to be the best fit for my application -- basically running a bunch of servers 24/7, including a particularly I/O intensive one.

Igor · July 3, 2016

Anyway, since USB sticks are cheaper than microSDXC cards, is there any reason to prefer a microSDXC card to a USB stick?

Nothing, if you don't care about fanciness related to physical size. SD card controller is limited anyway (background info) to around 23Mb/s while USB2.0 can go faster.

hiroshi · July 10, 2016

OK, so I've now ordered and received my Cubietruck. I decided to go with a 64GB Samsung EVO microSDXC card for storage (in addition to the 1TB hard drive), though I did consider getting a pair of USB sticks and setting them up in a BTRFS RAID 0 configuration. Two USB sticks should perform much better than the single microSDXC card because the USB ports on Cubietruck are independent. However, the improved performance would come at the cost of tying up the only (type-A) USB ports on the board. Also, I'm not sure that nand-sata-install would support such a setup?

Anyway...

I would like to hook up the Cubietruck serial console via a serial Bluetooth module (like this one), as described here for Cubieboard 1 and Cubieboard 2.

Now, since Cubietruck rather inconveniently does not provide 3.3V through UART0, is there any reason not to simply grab GND and 3.3V from pins 1 and 2, respectively, of CN8? I already have 2.54mm to 2.0mm jumper wires (such as these) as well as "normal" 2.54mm to 2.54mm ones.

Also, just to be absolutely sure, pins 1 and 2 of CN8 are the two CN8 pins closest to the SATA connector, as shown here, right? (That is, NOT the two CN8 pins closest to the Ethernet connector.)

Yes, I'm a total n00b so bear with me.