New variations of ransomware encrypt unmapped network shares, i suggest to NOT share the whole pool and start using FTP to backup your files. I locked down my pool, put Antivirus on it the Drivepool server and the Virtual Machines and opened up only folders that are temporary, like torrent downloads,temp etc, duplicated stuff are out of reach in the network and are accessed only through FTP. Also, Crashplan is a nice choise to backup your client pc's since it doesnt use shares or ftp but its own secure protocol.
Be strict and proactive and you're pool will be safe.
http://www.bleepingcomputer.com/news/security/dma-locker-ransomware-targets-unmapped-network-shares/