NAND jffs2 files system - binary & text files can exceeds the size of NAND

Question

I am writing an embedded application based on the ARM 9 v5 processor, and am using 64MB NAND. My problem is that when I copy the text or binary files of size 3-4 MB, the free physical memory gets reduced by only few KB, whereas ls -l shows the file size in MB.

By repeating the same process I reached one point where df command shows me 10MB size is free and du shows the total size as 239MB.

I have only 64MB of NAND, how am I able to add files up to 239MB of size?

Answer 1

JFFS2 is a compressed filesystem, so it is keeping the files compressed in the disk, which leads to this conflict. du lists the disk usage and df is the available capacity as seen by the filesystem.