It’s not the update at all (well, almost, I’ll explain). In previous versions, when the drive was rendered “too slow” to record, it just displayed an X. At least now they tell you what’s up. Here’s what’s happening:
1) The total video feed in a recent update was increased by 33% with the addition of the rear camera.
2) Video stream for 4 cameras is (30mb/min X 4 cameras) is 2mb/sec.
3) Most USB drives write at 3mb/s when new.
2 outta 3 right ain't bad
Most modern USB drives write many many many times faster than 3mb/s sequential when new.
USB UserBenchmarks - 639 USB Flash Drives Compared
The SLOWEST 64GB or larger drive of over 600 tested was writing sequential at over 9 MB/s... the second slowest was 11.5 MB/s, and the vast majority were in the 20-60 MB/s range... (a decent # were even faster than that but would be limited by the USB2 interface on the Tesla)
I
Once the data has to be “overwritten” write speeds can be cut in less than half. When that comes about, you get the error.
As pointed out 1/2 speed would still be more than fast enough on virtually any modern USB drive.
That said- flash-based storage medium DOES get slower as it fills up- and as it gets really full performance can drop by more than 1/2.... (the reason is a bit more complex than you described and relates to the ability to write at the page level but only erase at the block level, but that's really getting into the weeds without much benefit to most readers here).
Now- most modern OSes have code that helps avoid this issue- actually properly cleaning up the drive when files are deleted.
BUT... Tesla writes kinda crap software... their stuff didn't erase files on the USB storage AT ALL until recently, and still only does it when the drive is already nearly full. And possibly not very cleanly even when it does.
Now, the one thing I've mentioned I do regularly (about every 2-3 months) is I pull my Samsung USB key, plug it into a modern OS running PC, and delete all the video I no longer need.
The drive is usually only 1/3-2/3rds full when I do this so not full enough to really slow anything down at all... and since I'm deleting in a modern OS it's "cleaning up" after itself at the drive level too.
No need to wipe and reformat in that case. Though I suppose if you're only using it for video, and not music, doing the unneeded format isn't THAT much extra work than just a simple delete.
I suppose the above might explain why people think buying a "real" SSD "fixed" the problem- they're usually replacing something like a 64GB key with a 500GB or 1TB SSD- meaning it'd take them a LOT longer to get to 75%-90% full where performance starts taking a dump.
At which point the "fix" will be the same as it was on the cheaper USB key- clean it out.
