´df´ reports strange result

[tolou]

I'm getting my mmc booted system eaten up of something. The 'df' command is consisently reporting a decreased available size although the used size is quite stable.
Here's my output:
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/mmcblk0p2 2048 1784 264 87% /mnt/initfs
none 512 84 428 16% /mnt/initfs/tmp
/dev/mmcblk0p2 669224 555092 80136 87% /
none 512 84 428 16% /tmp
none 1024 68 956 7% /dev

The number of blocks & used is not calculating available blocks right.
What's going on? Is it bad blocks on the SD card? I've tried e2fsck without any help... I'm pretty soon going to reach the limit!

[tolou]

I suspect that there are plenty files and directoties, e.g in /proc and /sys with 0 kB that actually allocates some space in the memory which will not be included in the used space calculation. I have around 35 MB overhead like that.

The main problem seemed to be the 'wtmp' under /var/log that had grown to over 150 MB. Search 'wtmp' in the forum...