Value Meaning

GPT_ATTRIBUTE_PLATFORM_REQUIRED

0x0000000000000001

If this attribute is set, the partition is required by a computer to function properly.

For example, this attribute must be set for OEM partitions. Note that if this attribute is set, you can use the DiskPart.exe utility to perform partition operations such as deleting the partition. However, because the partition is not a volume, you cannot use the DiskPart.exe utility to perform volume operations on the partition.

This attribute can be set for basic and dynamic disks. If it is set for a partition on a basic disk and the disk is converted to a dynamic disk, the partition remains a basic partition, even though the rest of the disk is a dynamic disk. This is because the partition is considered to be an OEM partition on a GPT disk.

GPT_BASIC_DATA_ATTRIBUTE_NO_DRIVE_LETTER

0x8000000000000000

If this attribute is set, the partition does not receive a drive letter by default when the disk is moved to another computer or when the disk is seen for the first time by a computer.

This attribute is useful in storage area network (SAN) environments.

Despite its name, this attribute can be set for basic and dynamic disks.

GPT_BASIC_DATA_ATTRIBUTE_HIDDEN

0x4000000000000000

If this attribute is set, the partition is not detected by the Mount Manager.

As a result, the partition does not receive a drive letter, does not receive a volume GUID path, does not host mounted folders (also called volume mount points), and is not enumerated by calls to FindFirstVolume and FindNextVolume. This ensures that applications such as Disk Defragmenter do not access the partition. The Volume Shadow Copy Service (VSS) uses this attribute.

Despite its name, this attribute can be set for basic and dynamic disks.

GPT_BASIC_DATA_ATTRIBUTE_SHADOW_COPY

0x2000000000000000

If this attribute is set, the partition is a shadow copy of another partition.

This attribute is used by the Volume Shadow Copy service (VSS). This attribute is an indication for file system filter driver-based software (such as antivirus programs) to avoid attaching to the volume.

An application can use the attribute to differentiate a shadow copy volume from a production volume. For example, an application that performs a fast recovery will break a shadow copy LUN by clearing the read-only and hidden attributes and this attribute. This attribute is set when the shadow copy is created and cleared when the shadow copy is broken.

Despite its name, this attribute can be set for basic and dynamic disks.

Windows Server 2003:  This attribute is not supported before Windows Server 2003 with SP1.

GPT_BASIC_DATA_ATTRIBUTE_READ_ONLY

0x1000000000000000

If this attribute is set, the partition is read-only.

All requests to write to the partition will fail.
IOCTL_DISK_IS_WRITABLE will fail with the ERROR_WRITE_PROTECT Win32 error code, which causes the file system to mount as read-only, if a file system is present.

VSS uses this attribute.