microSD Cards Revisit


I’m in the market of storage for my new Rock Pi 4A which I’m going to use as the dedicated smart home controller. So the speed is not important but the endurance is, I could even remove the GUI completely since I’ll run it headless anyway.

In my mind microSD or any memory card is not made to last, so I ordered the M.2 extension board and planning to use SSD as the root file system just for that reason. Actually, I just learned using non high endurance microSD cards in Pi-like devices will void the warranty, according to SanDisk customer service.

I was totally surprised when doing a little homework on high endurance microSDs. I picked the products from 3 well established brands: Samsung, SanDisk and Kingston, here are the numbers (Samsung 970 Evo Plus is listed as reference):

I even thought it might be typos on Samsung part, but apparently it’s not, the warranty says it all. For the 128GB version, 43,800 hours of “full HD video recording” time make exactly 5 years.

Screenshot: warranty periods from Samsung’s website

Here are the image of the products in the comparison:

Selectable boot from eMMC and sdcard

great job! (characters patch)


I would use the eMMC chip for /boot if your going to use the NVMe as /root. I don’t think you will have endurance issues with the eMMC. I posted a guide on how to do what you are going to do if you are planning on using Home Assistant.


I wish there are TBW numbers for the eMMCs allnet is selling, theoretically the endurance of eMMC is somewhere between the regular microSD and TLC SSDs, but these high endurance microSDs redefined the concept. I received the 128GB Samsung card will run performance tests and post back. On RockPi4 microSD is limited to 50MB/s, the cards are rated at 30MB/s, it’s going to be interesting.

I’ve been running HA in Python virtualenv on Debian ARM64, I posted my experience some time ago:


As always, your posts are informative and inspiring for the rest of us :man_teacher:
It’s good to see someone making progress.

Me? I don’t know whether I’m just a dumb kid or in a bad marriage (perhaps both). Every day is another problem and no sex. :triumph:

‘Rockie’ and I would have separated or divorced a few weeks ago if you had not demonstrated its potential.


You are fine, the software on RockPi4 needs a lot of improvements indeed, I’ve been struggling too, but hope getting there soon.


Love your positive attitude, but you are years ahead of me in Linux experience. Gonna take a break from the Rock Pi for awhile, until I’m better prepared for the challenge. Better to learn on a solid foundation than to stumble around in the dark.

Meanwhile, I have some RPi’s, breadboards, sensor kits, and lots of projects. By the time I have achieved those objectives, Rock Pi and I will probably be much happier together.

Your HA project is very similar to my environmental control project for an aquaponic greenhouse, so I’ll be monitoring your progress.

Best Regards :sunglasses:


I pin high hope on Debian Buster (the next major release of Debian), when I tried some packages from Buster, seems it could use the hardware natively without any rockchip mods. We’ll see when it comes out


This is not specified in the datasheet of the report of the eMMC chip from Foresee. But usually the official statement is 800 to 1000 times full chip erasing/writing. From this, the life time is higher than the sd card.