Adoptable Storage Devices!
The M Preview released earlier today has a powerful new feature that allows you to "adopt" an external storage device (like an SD card or USB drive), enabling users to move both
app code (APKs) and private app data to that device. When a storage device is adopted, the platform wraps it in a layer of encryption and formats it similar to internal storage. (In contrast, the original Apps-on-SD feature launched back in Froyo could only move app code, not private app data.)
Also, to help users free up internal storage space, they can choose to migrate their "primary shared storage" (living at /sdcard) to any adopted device.
If you flash the preview build onto a phone/tablet, you can enable the adoption feature for testing with USB OTG devices by using the command described here:http://developer.android.com/preview/behavior-changes.html#behavior-adoptable-storage
Normally only storage devices in long-term stable locations (like an internal SD card slot inside a phone/tablet, or a USB drive attached to a TV) are supported for adoption.
Along with all of this work, the platform now has much better support for USB OTG storage devices (think USB flash drives). When a new device is inserted, a notification appears offering to "browse" that device along with simple options to manage/copy contents.
Please kick the tires and file bugs! :) #io15 #android