# Is verifying a MD5 sum after copying 100GB of data safe

backupchecksummd5

I'm copying 100GB from a Windows 7 workstation to 2 external drives (if you have only one backup, then you have none). All files have a MD5 checksum. I've verified all MD5 checksums on the external disks after the copy, and they were all correct.

I have a D:\ partition that holds all files I want to backup: mp3, documents, videos, etc. I'm moving to a mac, so software preferences aren't needed. My bookmarks are at delicious.com.

My question is: is this really a safe approach to avoid incorrect copies or corrupted files on my external disks? I'm going to format the machine and give it away to my brother, so I copied all files this way.

• If the checksums match then you are near a 100% safe the files were copied correctly, provided the external drive does not fail.