How disk space is partitioned in an Android phone? How does storage space in our phone is partitioned? How can we access our storage space?
Most Android phones have eMMC (flash memory), partitioned in GUID partition table (GPT) just like a PC's hard disk. There are usually less or more 50 partitions on a latest Android phone. OS uses /system while user uses /data mainly. Internal SD card is /data/media. Other partitions are smaller. 

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If you have a rooted phone, you can use Linux tools (parted, gdisk etc.) to manipulate Android 's partition table. But that's really risky.

To fully access storage space, you need root permissions.

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