After you have waited so long and created a data dump image of your hard disk or partition, you may want to checksum to verify for sure it is an exact image. This can easily be done with the md5sum command. For example, if sda2 is the device you are backing up,

md5sum /dev/sda2 > file.sda2.md5
dd if=/dev/sda2 of=sda2.img
mdsum sda2.img > file.sda2.img.md5

Now you can compare the checksum in the 2 files “file.sda2.md5” and “file.sda2.img.md5” to verify if they are the same.

If you are compressing your data dump image using gzip, then you can adapt the above commands slightly:

/home/user> md5sum /dev/sda2 > file.sda2.md5

/home/user> cat file.sda2.md5
1494b0debd0a4d9c59d3afeb16c5c77b  /dev/sda2

/home/user> dd if=/dev/sda2 | gzip > sda2.img.gz
979902+0 records in
979902+0 records out
501709824 bytes (502 MB) copied, 71.7573 seconds, 7.0 MB/s

/home/user> gunzip -c sda2.img.gz | md5sum > file.sda2.img.md5

/home/user> cat file.sda2.img.md5
1494b0debd0a4d9c59d3afeb16c5c77b  -

Please note that if you are going to write zeros into your hard disk or partition you want to backup, the md5sum will change. So you should checksum only after you zeroed. rio sosh code rio