Oracle received a set-back yesterday as IBM announced it wouldn't be officially supporting the database company's Linux product.

This follows Oracle's decision last October to resell Red Hat Linux alongside its eponymous database, in a move that many saw as a direct attack on bellwether open-source company Red Hat.

An IBM spokesman, Matthew McMahon, said that IBM couldn't state for certain that its software would be compatible with Oracle's Unbreakable Linux. Effectively, Big Blue's playing safe by waiting for assurances of compatibility with the 2,700 applications certified to run on Red Hat Linux. McMahon said that if there were customer demand for Oracle's product, IBM would support it.

Oracle claimed in response that its product is identical to Red Hat's, rebutting suggestions that its move would lead to a forking of the Linux kernel, and resulting in zero impact on applications.

However, according to one report, financial analysts are advising customers to ask for greater assurances of compatibility before switching to Oracle. One equities analyst said that Red Hat is selling peace of mind, which Oracle was not in a position to do because it couldn't certify compatibility.

And customers are responding likewise, with enterprises using applications such as IBM's DB2 and Tivoli unable to take a chance on the Oracle product. Oracle has announced no customer wins since it launched Unbreakable Linux.