Yesterday I reinstalled Ubuntu 13.04 64-bit on my computer (4GB RAM), and for the first time I decided to use Full Disk Encryption (all default settings).

Today while running backups my computer crashed twice.

Now I continued to work on my backups and when checking the hash of a backup of mine I found out that sha256sum showed a wrong result for a big file.

I skimmed over /var/log/syslog and I did not find any error, and the Disk utility also says that the Disk is OK.

I tried to reproduce that error, and for small files I didn't have this problem, but for big files I do:

$ dd if=/dev/zero of=zeroes bs=1M count=4000 && sha256sum zeroes && sha256sum zeroes

4000+0 records in

4000+0 records out

4194304000 bytes (4,2 GB) copied, 54,0345 s, 77,6 MB/s

ad6637bd22568145039a053da5cbf4c31d3eda5ef95c29646fa66b0cacd15a8c  zeroes

8ea0d0c9ad97de182335e98045a1f197456ceee782fa6e801fd3e68bea4d35d3  zeroes



$ md5sum zeroes && md5sum zeroes 

8097877e1c991721dae7ffe228ae2f5a  zeroes

fbd1e7fcd3861446310c87abf72066bf  zeroes

This is really bad if I can't rely on any of my data, so I would really appreciate if somebody could help me out finding out what the problem could be.