You see why I came to use vFAT? I did/do not see any advantages here for an ext FS. Just for storing map tiles. 4GB file ~ 4294967296 bytes Filesystem 1K-blocks Used Available Use% Mounted on /dev/loop0 4129759 3199535 930225 77% /home/user/MyDocs/.map so available are: 1k*4129759 ~ 4228873216 bytes Overhead seems to be only 66094080 bytes ~ 64MB My disk usage: du -xsh MyDocs/.maps 3.1G MyDocs/.maps du -xsh --apparent-size /home/user/MyDocs/.maps 2.9G /home/user/MyDocs/.maps to be more precise: du -xs MyDocs/.maps 3199535 MyDocs/.maps ~ 3276323840 bytes du -xs --apparent-size /home/user/MyDocs/.maps 3008856 /home/user/MyDocs/.maps ~3081068544 bytes So loss for storing around 3GB map tiles is only about 191MB. On ext there needs to be stored the inodes and also there is some space reserved for the super-user (man mkfs.ext2): -m reserved-blocks-percentage Specify the percentage of the filesystem blocks reserved for the super-user. This avoids fragmentation, and allows root-owned daemons, such as syslogd(8), to continue to function correctly after non-privileged processes are prevented from writing to the filesystem. The default percentage is 5%. 5% of 4GB is quite much (204MB) space lost on ext (excluding inodes space).