Despite the growing need for round-the-clock availability, more than seven out of 10 Oracle databases were down for more than an hour in the past year, according to the IOUG's April survey, which included 265 members -- most of them database administrators, developers or managers.

It wasn't natural disasters, power outages or security breaches that were behind most incidents, according to the survey. Security incidents led to only 1 percent of unplanned database outages. Power outages and natural disasters accounted for just 7 percent and 4 percent of unplanned database outages, respectively.

Hardware problems were behind almost half of the outages. Problems with the network, the application stack or the database itself contributed to about a third of the unplanned incidents, which could have more than one cause. Those experiencing both hardware and network problems were most likely to report that their databases were down for more than 15 hours.

Performance slowdowns were also common: 40 percent of respondents reported at least one slowdown every two months.

A full 80 percent said round-the-clock reliability was a necessity for at least some of their company databases. Moreover, 43 percent were governed by service-level agreements that required less than 24 hours of total downtime, including planned and unplanned, per year.