Carbonite, the consumer/small business online backup company, has struck a deal with Sun to piggyback on Java and offer a free 30-day trial of its widgetry to anybody who upgrades to the latest version of Java or downloads in for the first time.

Terms were not disclosed.

Java is said to be on 800 million PCs worldwide, an installed base Sun has never exploited, and Carbonite said it's trying to educate folk about the sanity of backing up.

The company, which competes with, say, EMC's Mozy, claims it's backed up 25 billion files and restored two billion lost files in its three-year lifetime. It offers unlimited storage and its widgetry installs in a few clicks, running in the background automatically backing up new or changed files over the Internet. The overhead is unclear.

The data leaving the local computer is encrypted and transmitted to Carbonite's server using HTTPS.

Gartner says the market should be worth $820 million in 2013, up from $300 million last year.

A Carbonite subscription cost $55 a year. Oracle, Sun's soon-to-be owner, is unlikely to interfere with the arrangement provided there's money in it.