Oracle support betrays a preference for Linux and x86

Now that Oracle 11g has hit shelves, the question many IT shops ask themselves is which hardware and operating system does Oracle run best on?

That's a question with no easy answers; Oracle supports its software on a variety of hardware platforms -- such as x86, RISC, mainframe -- and operating systems, such as Windows, Unix and Linux. Although Oracle 11g is available only on Linux x86 systems right now, it will eventually be released for Windows and Unix machines. But the combination of server and OS that takes the cake may depend less on raw performance and more on how much your hardware costs and what kind of service you're getting from Oracle and other vendors.

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