When Oracle chief executive Larry Ellison doubled down on Unix with his $5.6bn acquisition of Sun Microsystems, his customers were moving away from RISC systems.

Half of Oracle's customers are running their database instances on x86, while those who aren't will do so "shortly".

A survey of Oracle customers found that while just over two-thirds run their database environments on Unix - with Solaris the single most popular flavor - x86 is catching up.

The poll, just released, was conducted by the Independent Oracle Users' Group and surveyed 400 individuals - half DBAs - in organizations of varying sizes. VMware sponsored the study, called Towards a smarter information foundation.

Four out of 10 are already running Oracle instances on x86 servers with another six per cent planning to do so within the coming year, according to the IOUG.

IOUG also found that besides Oracle, Microsoft 's SQL Server - which only runs on Windows and x86 - is by far the most popular database (91 pet cent use it). It's followed by MySQL (44 per cent).

Virtualization is emerging as a way to help control the costs associated with bolting on all this extra x86, by cramming more instances of Oracle software and greater amounts of data on to the same or fewer boxes.

Sixty two per cent with Oracle on x86 use virtualization compared to 43 per cent for non x86-based Oracle sites. Cost savings associated with server hardware virtualization and an overall reduction in hardware costs were given as the leading reasons for companies adopting virtualization - 76 per cent and 59 per cent, respectively.

Among the top three issues hindering greater rollout: lack of budget is the biggest business obstacle (36 per cent) and political or organizational kick back (28 per cent). These included resistance from DBAs who'd had bad experiences with earlier versions of the technology and vendor support, with customers not running a version of virtualization software that the vendor has tested.

The technology hurdles to adoption were performance issues (38 per cent) and concerns about back up and restores, bottlenecks, and potential growth in storage and disk space needs (27 per cent in all cases). ®