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I have 32 GB sd card with two partitions. First is FAT partition has size 29 GB, second is ext4, nearly 3 GB (counted by Linux computer). But Android is showing that:

root@htc_a51ul:/storage/ext_sd # fdisk -l /dev/block/mmcblk1                   

Disk /dev/block/mmcblk1: 31.9 GB, 31914983424 bytes
255 heads, 63 sectors/track, 3880 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks  Id System
/dev/block/mmcblk1p1               1        3554    28545024   c Win95 FAT32 (LBA)
/dev/block/mmcblk1p2            3554        3881     2620416  83 Linux

First partition have 27,21 GB on Android and second only 2.49 GB. When I sum up blocks of both partitions (which are bytes) it's equals 29,72 GB. But sd card is 32GB. Why the difference?

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  • Not clearly an Android question, but rather about storage media: reserved blocks to protect your data in case something "breaks". See e.g. Formatting a new SD card (Ctrl-F and enter "reserved" ;) Affects usually ~5% of disk space.
    – Izzy
    Commented Dec 21, 2015 at 23:19
  • FAT file system doesn't support reserved block. Link that you provide is related to ext3 file system, not FAT.
    – QkiZ
    Commented Dec 22, 2015 at 9:13
  • All file systems need reserved space for management. Sorry I've not checked first the one in use here; but e.g. when bad blocks occure, their data must be saved somehow. And the Metadata must be stored somewhere. Find out about reserved sector areas for FAT at Wikipedia.
    – Izzy
    Commented Dec 22, 2015 at 9:47
  • But why on computer I see different values (the right ones)?
    – QkiZ
    Commented Dec 22, 2015 at 13:01

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