Encyclopædia Britannica it is scarcely used, and reviewers have recommended that it be dropped from the encyclopaedia. The also has color transparencies of human anatomy and several appendices listing the staff members, advisors, and contributors to all three parts of the Britannica. Taken together, the and comprise roughly 40 million words and 24,000 images. The two-volume index has 2,350 pages, listing the 228,274 topics covered in the "Britannica", together with 474,675 subentries under those topics. The "Britannica" generally prefers British spelling over American; for example, it uses "colour" (not "color"), "centre" (not "center"), and "encyclopaedia" (not "encyclopedia"). However, there are exceptions to
Software-defined data center According to some observers, software-defined data centers won’t necessarily eliminate challenges that relate to handling the differences between development and production environments; managing a mix of legacy and new applications; or delivering service-level agreements (SLAs). Software-defined networking was seen as essential to the software-defined data center, but it is also considered to be the “least mature technology” required to enable the software-defined data center. However, several companies, including Arista Networks, Cisco, Microsoft and VMware, market products to enable virtual networks that are provisioned, extended, and moved across existing physical networks. Several competing network virtualization standards already existed by 2012. Neutron,