Dual boot microsd/eMMc?

[MarkHaysHarris777]

Hi all, I just received my rock64 and I want to use it mainly as a small NAS with OMV installed in the eMMc. Is it possible to have Android on the microSD and using the jumper to have both systems at the same time?

Certainly;  that's the whole point, really.   The eMMC has boot priority ,  and if the jumper is in place the eMMC clock line is held to ground effectively disabling the eMMC -- if the SD card has a valid image it will boot from there;