I have an ext4 filesystem for which the reported disk usage is not correct. I have noticed the discrepancy after I rsync-ed the content to another filesystem and noticed that the used space on the target is almost double of the size reported on the source. Both machines are running the same software - with the same kernel version and same coreutils version (which I later upgraded to latest available version). Both filesystems are clean (verified with fsck.ext4). No sparse files. After further investigation I think that the problem is most likely on the source machine. Here is the du output for for one directory exhibiting the problem:
#du -h |grep /51 201M ./51/msg/8 567M ./51/msg/9 237M ./51/msg/6 279M ./51/msg/0 174M ./51/msg/10 273M ./51/msg/2 341M ./51/msg/7 408M ./51/msg/4 222M ./51/msg/11 174M ./51/msg/5 238M ./51/msg/1 271M ./51/msg/3 3.3G ./51/msg 3.3G ./51
after changing the directory and running du again I get different numbers
#cd 51 du -h 306M ./msg/8 676M ./msg/9 351M ./msg/6 338M ./msg/0 347M ./msg/10 394M ./msg/2 480M ./msg/7 544M ./msg/4 407M ./msg/11 312M ./msg/5 326M ./msg/1 377M ./msg/3 4.8G ./msg 4.8G .
Do you have any idea what could cause this behaviour?