Sun expands its storage business

MARLBORO — Sun Microsystems, Inc. is paying $400 million HighGround Systems, Inc., based here. HighGround makes data storage management systems, an area into which Sun, based in California, is trying to expand. Sun is competing with EMC Corp. of Hopkinton, Mass., the dominant large-scale data storage company. HighGround produces storage resource management software, which Sun wants to use rather than develop its own software.