Changing disk status
Changing disk status is effective for Windows Vista SP1, Windows Server 2008, Windows 7 operating systems and applies to the current disk layout.
One of the following disk statuses always appears in the graphical view of the disk next to the disk’s name:
The online status means that a disk is accessible in the read-write mode. This is the normal disk status. If you need a disk to be accessible in the read-only mode, select the disk and then change its status to offline by selecting Change disk status to offline from the Operations menu.
The offline status means that a disk is accessible in the read-only mode. To bring the selected offline disk back to online, select Change disk status to online from the Operations menu.
If the disk has the offline status and the disk’s name is Missing, this means that the disk cannot be located or identified by the operating system. It may be corrupted, disconnected, or powered off. For information on how to bring a disk that is offline and missing back online, please refer to the following Microsoft knowledge base article: http://technet.microsoft.com/en-us/library/cc732026.aspx.