The cloud storage provider, Dedoose, recently announced a technical failure that caused academics across the country to lose research work. Dedoose is working to recover the lost data, but it’s possible some of it will be unrecoverable. For more information about the Dedoose problem: http://chronicle.com/blogs/wiredcampus/hazards-of-the-cloud-data-storage-services-crash-sets-back-researchers.
No single storage option is 100% effective, which is why it’s important to have backups of all your important files. Best practice is to have two copies on-site (ex: your computer and an external hard drive) and one copy off-site (either cloud storage or a remote server). MIT has some good information about backing up your data.