Before you can store, read, and write data on a new data disk that is attached to a Windows Elastic Compute Service (ECS) instance, you must initialize the disk. The initialization operations include bringing the disk online and partitioning and formatting the disk. This topic describes how to initialize a data disk up to 2 TiB in size on a Windows instance.


A data disk is attached to an ECS instance. For more information, see Attach a data disk.

Background information

The example in this topic uses an ECS instance and a data disk that have the configurations described in the following table. Operations may vary based on actual conditions.
Operating systemResourceDescription
Windows operating systemImage used by the instanceWindows Server 2012 R2 64-bit
Data disk
  • Disk name: Disk 1
  • Disk capacity: 40 GiB
Note For information about how to initialize a disk that is larger than 2 TiB, see Initialize a data disk that is larger than 2 TiB in size.


  1. Connect to the ECS instance.
  2. On the Windows Server desktop, right-click the Start icon icon and select Disk Management.
  3. Find the data disk that you want to initialize and is in the Offline state. In this example, Disk 1 is used.
  4. Right-click the blank area around Disk 1 and select Online.
    When the disk goes online, Disk 1 enters the Not Initialized state.
  5. Right-click the blank area around Disk 1 and select Initialize Disk.
  6. In the Initialize Disk dialog box, select the disk, select a disk partition format, and then click OK.
    Important An MBR partition cannot be larger than 2 TiB in size. If the disk for which a partition is created is larger than 2 TiB or if the disk may be resized to larger than 2 TiB, use the GPT partition format.
  7. Right-click the Unallocated section of Disk 1 and select New Simple Volume.
  8. In the New Simple Volume Wizard window, click Next and complete the initialization operation.
    1. In the Specify Volume Size step, set Simple volume size in MB and click Next.
      If you only need to create a primary partition, use the default value. You can also specify the size of the simple volume based on your needs and divide Disk 1 into multiple partitions.
    2. In the Assign Drive Letter or Path step, select Assign the following drive letter, select a drive letter, and then click Next. In this example, D is selected for the drive letter.
    3. In the Format Partition step, select Format this volume with the following settings, configure formatting settings, and then click Next.
    4. View the information of the new simple volume and click Finish to close the New Simple Volume Wizard window.


In This PC, you can find a new drive named New Volume (D:). The data disk is ready for use.