Re: Trouble using SDXC 128GB card
Am Tue, 26 Oct 2021 15:41:33 +0000
schrieb Musbur <musbur@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).
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