# Data Object - HostVmfsSpec(vim.host.VmfsVolume.Specification)

Property of
  VmfsDatastoreCreateSpec
Parameter to
  FormatVmfs
Extends
  DynamicData
See also
  HostScsiDiskPartition, VmfsUnmapBandwidthSpec

## Data Object Description

This data object type describes the VMware File System (VMFS) creation specification. Once created, these properties for the most part cannot be changed. There are a few exceptions.

Properties

Name | Type | Description
--- | --- | ---
blockSize* | xsd:int | The block size of VMFS in kilotypes (KB). Determines the maximum file size. If this optional property is not set, the maximum file size defaults to the maximum file size for the platform. In VMFS3, the valid block sizes are 1MB, 2MB, 4MB, and 8MB. In VMFS5, the only valid block size is 1MB. In VMFS6, the valid block sizes are 64KB and 1MB. Since vSphere API 6.5
blockSizeMb* | xsd:int | Deprecated. As of vSphere API 6.5, use blockSize instead. The block size of VMFS in megabytes (MB). Determines the maximum file size. If this optional property is not set, the maximum file size defaults to the maximum file size for the platform. In VMFS2, the valid block sizes 1MB, 2MB, 4MB, 8MB, 16MB, 32MB, 64MB, 128MB, and 256MB. In VMFS3, the valid block sizes are 1MB, 2MB, 4MB, and 8MB. In VMFS5, the only valid block size is 1MB.
extent | HostScsiDiskPartition | Head extent of VMFS. The head extent identifies the VMFS. However, the head extent should not be used to identify the VMFS across host reboots. The actual identifier is specified in "vmhbaI:T:L" format which is not guaranteed to be stable across reboots. Define a volume name that is unique to the host and use it to refer to the VMFS. Alternatively, the immutable UUID of the VMFS can be used after it is created.
majorVersion | xsd:int | Major version number of VMFS. This can be changed if the VMFS is upgraded, but this is an irreversible change.
unmapBandwidthSpec* | VmfsUnmapBandwidthSpec | VMFS unmap bandwidth related specification. See VmfsUnmapBandwidthSpec for detail. Since vSphere API 6.7
unmapGranularity* | xsd:int | The granularity of VMFS unmap operations. VMFS unmap reclaims unused storage space. The unit is KB. The minimum unmap granularity is 8KB. The maximum unmap granularity is determined by the block size of VMFS blockSize. Since vSphere API 6.5
unmapPriority* | xsd:string | VMFS unmap priority. VMFS unmap reclaims unused storage space. This determines the processing rate of unmaps. See HostVmfsVolumeUnmapPriority for supported values. Since vSphere API 6.5
volumeName | xsd:string | Volume name of VMFS.
Properties inherited from DynamicData
None

*Need not be set
Show WSDL type definition
<complexType xmlns="http://www.w3.org/2001/XMLSchema" xmlns:vsan="urn:vsan" name="HostVmfsSpec"> <complexContent> <extension base="vsan:DynamicData"> <sequence> <element name="extent" type="vsan:HostScsiDiskPartition"/> <element name="blockSizeMb" type="xsd:int" minOccurs="0"/> <element name="majorVersion" type="xsd:int"/> <element name="volumeName" type="xsd:string"/> <element name="blockSize" type="xsd:int" minOccurs="0"/> <element name="unmapGranularity" type="xsd:int" minOccurs="0"/> <element name="unmapPriority" type="xsd:string" minOccurs="0"/> <element name="unmapBandwidthSpec" type="vsan:VmfsUnmapBandwidthSpec" minOccurs="0"/> </sequence> </extension> </complexContent> </complexType>