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+--- Thread: Question to anyone with entire system on NVMe (/showthread.php?tid=8729)
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RE: Question to anyone with entire system on NVMe - as400 - 01-10-2020
SD cards all have one common problem. They are just not trustworthy. It's just a matter of time when you end up with broken sd card or irreversible filesystem error.
P.S. My ANSI PBP just came this minute
RE: Question to anyone with entire system on NVMe - wdt - 01-10-2020
well, I wonder about the uSD slot, is it 50 mHZ (nibbles) or uhs104
>They are just not trustworthy (uSD)
It depends, consider thr raspberry and armbian experience
With rasp, the biggest problem is undervoltage, from a crappy cable and connector
With armbian, crappy cards, they all shout "test with iozone"
If you have a quality card, not undervolted, not 80+% full,,
the card should have a reasonable life
If the card is only 1/2 full, lots of room for wear leveling
And if you test with iozone, you quickly realize
that 90% of cards are crap for SBC purposes, OK for cameras
(and that's fair, that is what they were made for)
There is an immense amount of ignorance about flash,
exploited by the makers. More for less is good, right?
Not in this case, example SLC ->MLC ->TLC ->QLC,, bigger, better, right?
NO
voltage levels = bits
SLC (0, 1),,,MLC(0, 1/2, 1),,, TLC(0, 1/3, 2/3, 1),,,QLC(0, 1/4, 1/2, 3/4, 1)
It should be obvious which will last longer, but unfortunately smaller
And when they say "Made for FAT" that means the first 1G are written SLC
so that the MBR and PBR and FAT table are reliable
So, older (4 year) cards, if a reasonable size and quality are quite valuable
If made with quality cells, SLC, unless you are really hammering it, will
last until you lose it
You can see that in the newest nvme controllers, a new drive is 1/2 SLC, as cache,
shrinking to 10% as the drive fills