Applies To: Windows 10, Windows 8.1, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, Windows Server 2012
This topic and its subtopics discuss using Disk Management to manage the disks in a computer, and includes information about initializing new disks, converting disks between different partition styles, and how Windows handles the online status of new disks.
Online and offline status
Disk Management displays whether a disk is online (available), or offline.
In Windows, by default, all newly-discovered disks are brought online with read and write access. In Windows Server, by default, newly-discovered disks are brought online with read and write access unless they are on a shared bus (such as SCSI, iSCSI, Serial Attached SCSI, or Fibre Channel). Disks on a shared bus are offline the first time they are detected.
If a disk is offline, you must bring it online before you can initialize it or create volumes on it.
To bring a disk online or take it offline, right-click the disk name and then choosing the appropriate action.