I just ordered my first Black today. I have been using RPi’s for awhile but due to the lousy USB interface I wanted to try the Black. Anyhow I have a few questions.
I plan to run Debian and I see I have the option of running it in microSD or the internal EMMC.
I am not clear on the advantage/disadvantage of one vs. the other. I know I want to be able to boot at power up without pushing buttons so I suspect the EMMC image is the best choice. When an OS is flashed to EMMC the data (writable) area is Where? In RAM or MicroSD?
I want to customize the OS and add my own code is this done on the microSD image and then flashed?
I am not clear on how this works. Of course on the RPi the SD card is the OS and and changes you make are stored there. Maybe there is a document that explains this?
I just ordered my first Black today. I have been using RPi's for awhile but
due to the lousy USB interface I wanted to try the Black. Anyhow I have a
few questions.
I plan to run Debian and I see I have the option of running it in microSD or
the internal EMMC.
I am not clear on the advantage/disadvantage of one vs. the other.
uSD is swappable and typically larger
eMMC is faster and more reliable over time
I know I
want to be able to boot at power up without pushing buttons so I suspect the
EMMC image is the best choice.
You can boot from uSD without pushing a button on power cycle. The
button press is only needed when "unbricking" the on-board eMMC.
When an OS is flashed to EMMC the data
(writable) area is Where? In RAM or MicroSD?
Things could have been done to run more out of RAM, but it isn't the
case. Many things write back to the eMMC.
I want to customize the OS and add my own code is this done on the microSD
image and then flashed?
The eMMC works just like uSD. You write to it using the file system as
you run. I highly suggest managing your code using 'git'.
I am not clear on how this works. Of course on the RPi the SD card is the OS
and and changes you make are stored there. Maybe there is a document that
explains this?
Not much to explain. eMMC is just SD soldered down to the board. You
can access both when running off of either.
On the emmc my understanding is that it had a more refined internal controller that did wear leveling a little better than SD or mSD cards. Whether or not this is the case when using the emmc with Linux it will eventually fail. How long is anyones guess and depends on the application and how you handle writes and where you store temporary data.
So I am curious how users are doing this in their applications? Internal, external? Are you worried about write life of the emmc?
Also are there speed differences when using the emmc vs external mSD?
eMMC uses similar NAND devices as the eMMC. Write life is not a major concern. With SD cards, you do not know what you are getting. They use a lot of different controllers and the worst NAND they can find.
The 2GB eMMC won’t be used much longer on the BBB. When we move to 4GB, you will have more room to move around.
Jason, I’d just like to point out that when the SD card slot is brought up in 4bit mode, it is barely slower than the eMMC. We’re talking only a few hundred kilobytes /s