These task sequence variables govern the operation of the task sequence action. Variables marked as input variables are read or used by the task sequence action. In most cases, input variables correspond to task sequence action fields in the task sequence editor and can be set via that user interface. Alternatively, input variables can be set at runtime from per-collection or per-computer variables, via the Set Task Sequence Variable action or via the TSEnvironment COM object. Variables marked as output variables are written or set by the task sequence action to be read by later actions in the task sequence.

Format and Partition Disk Task Sequence Step

Action Variable Name Description



Specifies the physical disk number to be partitioned.



Specifies whether or not to disable cache alignment optimizations when partitioning the hard disk for compatibility with certain types of BIOS. This may be necessary when deploying Windows XP or Windows Server 2003 operating systems. For more information, see KB article 931760 ( and KB article 931761 (

Valid values:


"false" (default)



Specifies whether or not to create an EFI partition on a GPT hard disk so that it can be used as the startup disk on EFI-based computers.

Valid values:


"false" (default)



Specifies an array of partition settings; see the SDK topic for accessing array variables in the task sequence environment.

This task sequence variable is an array variable. Each element in the array represents the settings for a single partition on the hard disk. The settings defined for each partition can be accessed by combining the array variable name with the zero-based disk partition number and the property name.

For example, the following variable names can be used to define the properties for the first partition that will be created by this task sequence action on the hard disk:

If multiple partitions will be defined with this task sequence action, the properties for the second partition can be defined by using their index in the variable name; for example, OSDPartitions1Type, OSDPartitions1FileSystem, OSDPartitions1Bootable, OSDPartitions1QuickFormat, OSDPartitions1VolumeName, and so on.
  • OSDPartitions0Type - Specifies the type of partition and is a required property. Valid values are "Primary", "Extended", "Logical", and "Hidden".

  • OSDPartitions0FileSystem - Specifies the type of file system to use when formatting the partition. This is an optional property; if no file system is specified, the partition will not be formatted. Valid values are "FAT32" and "NTFS".

  • OSDPartitions0Bootable - Specifies whether the partition is bootable and is a required property. If this value is set to "TRUE" for MBR disks, then this will be made the active partition.

  • OSDPartitions0QuickFormat - Specifies the type of format that should be used and is a required property. If this value is set to "TRUE", a quick format will be performed; otherwise, a full format will be performed.

  • OSDPartitions0VolumeName - Specifies the name that should be assigned to the volume when it is formatted. This is an optional property.

  • OSDPartitions0Size - Specifies the size of the partition. Units are specified by the OSDPartitions0SizeUnits variable. This is an optional property. If this property is not specified, the partition is created using all remaining free space.

  • OSDPartitions0SizeUnits - Specifies the units that will be used when interpreting the OSDPartitions0Size task sequence variable. This is an optional property. Valid values are "MB" (default), "GB", and "Percent".

  • OSDPartitions0VolumeLetterVariable - Partitions will always use the next available drive letter in Windows PE when they are created. Use this optional property to specify the name of another task sequence variable, which will be used to save the new drive letter for future reference.



Specifies the partition style to use when partitioning the disk. "MBR" indicates the master boot record partition style, and "GPT" indicates the GUID Partition Table style.

Valid Values:



See Also