SugarSync — makers of the SugarSync file sync, backup and file sharing service, — say they now host more than two petabytes of user data.

“This significant milestone highlights the trend toward mainstream adoption of combination cloud sync/back up services,” says CEO Laura Yecies. “It also validates the scalability of our infrastructure and service.”

SugarSync also released a handful of key statistics to further illustrate its growth. From March 2009 – March 2010, the amount of customer data added on a daily basis to SugarSync’s private secure data centers more than quintupled, from 1 terabyte/day to 5 terabytes/day. Average inbound traffic multiplied from 189 Mbps/day to 743 Mbps/day.

As an incentive for new customers to try all of SugarSync’s new features, the company also announced a special offer: new users can earn an extra free 1GB of space simply by sharing on social media which feature encouraged them to download the service. SugarSync’s referral program also offers users the ability to earn up to 105GB of free space through friends-and-family sign-ups. The new offer is available at .