Do you use the wonderful open source reference management solution Bibdesk / Bibtex and the synchronisation software Ox Drive, which is, for example, used by the privacy-aware mailbox provider Mailbox.org? Have you ever run into trouble with your .bib (bibliography files) getting messed up or do you want to avoid them getting messed up?
Make sure you always have sufficient free back-up space on your Ox Drive! Otherwise the .bib file gets duplicated, with one version upon another piling up and, on the way, references getting lost ..
However, even then data may get lost, for whatever reason. To avoid this, save your .bib file not in a synced folder but on an ordinary folder on your hard disk. Then set up an automator work flow to make daily backups from the non-synced folder to the synced folder.