LinkIt ONE provides an SD card slot and 10 MB of internal flash storage. You can manipulate these two storage areas using the LSD and LFlash classes.
The LSD class is for the LinkIt SD card slot. If you would like to use an Arduino SD shield, use the SD library provided by Arduino instead. As a result you can mount and use an Arduino SD shield at the same time as using the LinkIt SD card slot.
To manipulate a file or folder, use LSD.open() or LFlash.open() to get an LFile object then:
The built-in SD card and SPI functions are exclusive. Before using the SD APIs, make sure the settings switch is correctly set (see Figure in SPI). Please note that once the board is configured to SD, calling SPI APIs may result in unexpected SD behavior.
If you want to use SD and SPI at the same time, please use an external SD shield.