WordPress have a option to take backup of your blog . It is very important to keep a hard copy of your blog.
There is always a chance to loose data online. No need to take any risk for your valuable post.
1. Goto wp-admin from Left side menu ->Tools
2. Choose the export option
3. Select one
Then all blog contents are getting in the form of .xml file.
If anything happens to your blog then very easily can recover your WordPress blog .