eMMC support & concerns

[Cláudio Vieira]

Hello Matt,

Thanks for your feedback!

I’m still waiting for a ZimaBoard to be delivered, but trying to plan ahead!

The idea is to use it as a tiny home server in always on operation mode.
eMMC performance shouldn’t be an issue once the system has booted.

I will play with it and try a standard DragonFly install with HAMMER2.
Next step will be to make it eMMC friendly by applying your suggestions.

I will share my findings here as a follow-up to this thread...

Cheers,
Cláudio Vieira


> On 11 Feb 2023, at 05:05, Matthew Dillon <dillon at backplane.com> wrote:
> 
> Well, the first question is whether DFly can even probe the eMMC.  If you can boot DFly from a usb stick and play with it from there, that's the easiest way to check which resources are or are not supported.
> 
> We do have eMMC support and generally speaking your research is correct... it is not a good idea to do heavy writing to eMMC, and the transfer rate is very slow (it is literally a serial protocol that runs in the megabit range rather than the gigabit range).  eMMC is suitable for booting systems and reading, but writing should be minimized.   eMMC performance is poor regardless of the operating system.  That said, operating systems like Linux or the BSDs will extensively cache read data in memory so it is possible to have decent responsiveness.
> 
> Beyond that, DFly can be made relatively eMMC-friendly by not configuring any swap space (unless absolutely necessary), and using tmpfs filesystems for /tmp and /var/tmp (also /var/run/shm but that is typically already tmpfs based).  Hammer2 should work fairly well with it.  The larger the eMMC drive, the better.
> 
> -Matt