Add README

README.md

@@ -0,0 +1,39 @@
+# VMbackup
+
+## What is this?
+
+A tool with which VMs can be easily backed up to an external drive.
+
+## How does this work?
+
+It optimizes the data copied by hashing chunks and store this hash index alongside the VM on the external drive. When
+running the backup again, it reads the VM from the local disk, hashes the chunks and compares the hash to the hash index
+on the external drive. Only chunks with a different hash are copied (that means that the chunk has changed and needs to
+be updated). This optimization has a positive effect only if the local disk is faster than the external drive.
+
+## What about hash collisions?
+
+Uh oh.
+
+## Can I use this to back up my production VMs?
+
+I haven't tested it that thoroughly that I would recommend that. But I can't and won't stop you. Please report back how
+it went.
+
+## Does this only work with VMs?
+
+No, it works on every file. I just use it for VM backups.
+
+## How to use
+
+```
+vm-backup SOURCE TARGET
+```
+
+## Author
+
+Moritz Halbritter ([@phxql](https://github.com/phxql))
+
+## License
+
+[GPLv3](LICENSE)