As IBM moves forward with its $34 billion deal to buy Red Hat, its executives continue to defend the acquisition. The deal, announced in October, brings together two of the Triangle’s biggest employers – IBM, which has one of the largest footprints in Research Triangle Park, and Red Hat, which occupies downtown Raleigh’s Red Hat Tower. But, as Mark Foster, senior vice president of global business services, pointed out at a recent analyst conference, the pair have long been partners.