I use and recommend the BackWPup plugin for wordpress, it has some greate features – most importantly the option to backup to Dropbox upon completion of your backup.
After a recent migration to a new VPS I attempted to run a backup once my configuration was complete. I was greeted with the following error: missing function curl_exec
After a bit of research I found that my nice new VPS did not have php5-curl installed so BackWPup could not function correctly. To resolve this issue either ask your hosting provider or SSH onto your VPS and run the following command.
sudo apt-get install php5-curl
Once done you will be able to run your BackWPup job with no problems