Ein Blick in die Physical Layer Simplified Specification Version 6.00 für SD-Karten offenbart unter Kapitel 4.3.5 das ERASE-Kommando (CMD38) für SDHC- und SDXD-Cards. Unter 4.3.5.2 heißt es:
The DISCARD operation is similar to the default ERASE operation. Card may de-allocate the discarded blocks partially or completely. The contents of a region where the discard function has been applied shall be treated as ‘don’t care’ by host. After discard operation the previously written data may be partially or fully read by the host, depending on the card implementation.
It is desirable to discard many write blocks simultaneously in order to enhance the data throughput. Identification of these write blocks is accomplished with the ERASE_WR_BLK_START (CMD32), ERASE_WR_BLK_END (CMD33) commands. The host should adhere to the following command sequence: ERASE_WR_BLK_START, ERASE_WR_BLK_END and DISCARD (CMD38)
Das ist ungefähr das Äquivalent zum TRIM-Befehl bei SSDs. Nun macht die SD Association keine Angaben, ob ihr Formatter dieses Kommando wirklich nutzt. Bei diversen $OS-Boardmitteln bin ich jedenfalls deutlich weniger zuversichtlich.