Open source technologies are enterprise-class and increasingly can be found in the data center, as vendors begin addressing the challenge of offering scalable, robust, reliable products based on open-source technology.Consider these examples:* PathScale recently announced an open-source optimized compiler and MPI libraries that allow data center managers to deploy 64-bit high-performance computing using an AMD64 processor-based Linux cluster. Applications for which this product might make sense include number crunching for pharmaceuticals or insurance estimates.* The vast majority of the emerging \u201cdata center appliances\u201d - such as XML accelerators, XML firewalls, content caching appliances, firewalls and intrusion-detection systems - run an open source operating system at their core (either BSD-based or Linux-based). The use of open source operating systems in the \u201cembedded systems\u201d market can be attributed to the flexibility, customizability and low cost of the operating system.* Red Hat recently made good on its promise to release the Global File System (GFS) software suite and its associated management tools under an open-source license. Red Hat obtained GFS from its acquisition of Sistina, a storage infrastructure company. GFS is an enterprise-class clustering file system that allows a cluster of Linux servers to share storage across several nodes while retaining data consistency, rapid access, and fault tolerance. Most importantly, GFS is optimized for Oracle\u2019s 9i Real Application Clusters (RAC), enabling Oracle RAC to run without local storage on a shared Oracle "home" directory. GFS makes it a lot easier to add or resize storage on the fly or add Oracle servers to meet a sudden spike in demand. GFS brings to Linux a level of storage virtualization, scalability and reliability that makes it directly competitive with products based on proprietary Unix. A particular strength of the Red Hat version of GFS is its sophisticated managed capabilities.\u00a0As with many open source projects, the key advantage of the open license is not the ability to download the software for free, but the ability to freely modify and customize it. It is a matter of liberty, not price - or as the GNU Software Foundation puts it: \u201cThink of free as in \u2018free speech\u2019 not as in \u2018free beer.\u2019\u201dNow that GFS is open source, we expect it will be "adopted" by many of the other Linux distributions (such as SuSE) and further developed and customized by large system integrators (such as IBM).Similarly, in the embedded systems market (appliances), many of the customizations and optimizations made by vendors have made their way back into the general operating system, further fueling the growth in the use of Linux on appliances.Bottom line: Whether you look at open source technologies for the low total cost of ownership, or for the ability to make extensive modifications and customizations, open source is already a significant data center technology and is worth considering.