2W0NRE wrote: ↑Thu Dec 02, 2021 8:27 am
Using the same ones in Pis running Octoprint and Raspbian
Are they the same lot number?
Kingston doesn't have a chip foundry -- they buy batches of low-bid chips from various chip foundries and put their labels on them. Two chips with identical labels bought within days of each other could easily be from two separate chip foundries, and have completely different internal behavior. Especially if they are Class-10 rated.
Class-10 is rated for /streaming/ data (eg: video) on a freshly formatted card. It may only handle two open "allocation units" (one for the FAT/bitmap, since FAT is the default formatting; the other is for the actual streamed data). Class-2/4/6 are rated for fragmented cards (what you'd get in a still image camera that has had some images deleted while others may still be getting transferred from camera RAM buffering. These often handle 3-6 allocation units (useful for journalling file systems as it can keep the journal in buffers while writing data, along with having multiple files open for output in parallel). For OS usage, a high-end Class 2/4/6 card with 6 "allocation unit" capability can be much faster than a low-end Class 10 card.
SanDisk manufactures there cards, and I believe so does Samsung (though I've never seen a Samsung card on the open market). Not sure of the status of Transcend and Lexar though they seem to be on the higher-end quality. Kingston and PNY are lower-end cards.