The SD Association has announced a new performance standard for SD cards aimed at improving customer experiences and delivering more consistent performance metrics. The new performance information has become necessary because of Android's new "Adoptable Storage" capability, which was introduced just over a year ago with the debut of Marshmallow. Prior to Marshmallow, Android overwhelmingly preferred to use internal storage for all of its applications and data. Certain apps could be deployed on SD cards, but saving data directly to an SD card was often a multi-step process, and many applications didn't run off SD cards at all. Instead, SD card storage was principally used for audio, image files, or video files rather than application storage.
This had knock-on effects on how the SD card standards evolved, and the SDA focused its efforts on ensuring high performance for reading or writing sequential data. The new App Class(Opens in a new window) cards, in contrast, target a read speed of 1500 IOPS, write speeds of 500 IOPS, and a sustained transfer rate of 10MB/s at minimum. The stated goal of the program is to address two problems with the current Adoptable storage program.
Adoptable Storage configuration in Marshmallow.
1). If the SD card inside an Android device is less than 25% as fast as the internal storage, users receive a message warning them that the SD card is slow. Tests have indicated that many applications run perfectly well on "slow" SD cards, though your mileage will vary depending on the app in question, obviously.
2). Consumers currently have no way to determine if an SD card is fast enough for their use-case before buying it and installing it in their smartphone or tablet, which could leave them unhappy or under the impression that their new hardware isn't fast enough.
Logos will be available in both a short and long form, as shown below:
Google has relaxed its benchmark for Nougat compared to Marshmallow, which may explain why the SDA has targeted relatively easy specs. With Marshmallow, your attached storage had to be at least 25% as fast as internal memory. Nougat, in contrast, will run a benchmark and compare against a static performance level. This is probably the better option as far as guaranteeing customer satisfaction; continually improving internal NAND means that an SD card that offers perfectly acceptable performance in 2016 might suddenly start reading as slow in 2017 if a smartphone's NAND performance improves.
The new App Class will be introduced by the SD 5.1 Performance Specification update. For now, only one level of classification is being introduced, though this could change in the future if manufacturers see value in higher classifications or consumers demand it. Note that this label is in addition to Video Speed Class rather than a replacement for it -- SD cards rated V10, V30, V60, or V90 offer sequential performance of 10MB/s - 90MB/s, but don't make any guarantees about sustained IOPS.
