You may use the diskpart utility for Microsoft Windows Server 2003 (as well as various other version of Microsoft Windows) to extend the size of a volume on the server after it has been expanded on a storage area network (SAN). The Microsoft TechNet website is a great resource for Information Technology (IT) professionals who administer Microsoft technology. For instance, the link below provides detailed documentation by Microsoft for utilizing the diskpart utility.

http://support.microsoft.com/kb/300415

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