Am Tue, 26 Oct 2021 15:41:33 +0000 schrieb Musbur <mus...@posteo.org>:
>I'm using a Lenovo Thinkpad T480s. Recently I bought a SanDisk Extreme >Pro 128GB SDXC card for my digital camera, but I quickly found out that >the system can't work with that card. >..... >The camera can format, read and write just fine. Perhaps this link https://github.com/ThomasKaiser/Knowledge/blob/master/articles/A1_and_A2_rated_SD_cards.md#application-performance-class-2-a2 may explain, why you have these problems. Specially the following text is interesting: >Application Performance Class 2 (A2) >A2 promises even better performance with 4000/2000 read/write IOPS >minimum but there's a problem since as outlined by the SD Association A2 >cards show "much higher performance than A1 performance by using >functions of Command Queuing and Cache". > >Cache and Command Queuing require host (driver) support since the host >needs to activate those new features first. The cache feature on A2 rated >cards makes use of volatile RAM on the card requiring the host to learn >new commands to issue flushing the cache (involving the risk of data >losses -- for details see especially chapter 4.17 in Physical Layer >Simplified Specification 6.0) For my raspi-like hosts I avoid to buy A2 cards. With my A1 sdxc cards I have no problems (neither with a built-in card reader nor an USB card reader).
