If the size and number of recent bets laid by vendors is anything to judge by, 2008 will be the year that online back-up becomes mainstream. In the last four months, no lesser players than IBM, EMC, Symantec and Microsoft have either bought online back-up suppliers, or launched their own online back-up services. The biggest triggers for demand are the increasing burden of backing up ever-growing volumes of data, especially for small and mid-sized businesses (SMBs) with limited IT resources, and - across all sizes of business - an increasing sensitivity to the risk of IT disaster.