They're big binary blobs. If the tables aren't locked while you're backing up, you're going to end up with inconsistent data. There are tools like xtrabackup

They're big binary blobs. If the tables aren't locked while you're backing up, you're going to end up with inconsistent data. There are tools like xtrabackup that allow you to extract a live copy of the files, but sometimes take some hand loving to get working on another system. A good solution I found when wanting to copy those particular files instead of a dump/restore was to utilise the snapshotting features of LVM. e.g. 1. lock tables 2. take snapshot 3. unlock tables 4. mount snapshot and copy data from it Then the system continues to work and you have a consistent copy to back up.