Applies to: Windows Server 2022, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, Windows Server 2012

Displays or sets the storage area network (san) policy for the operating system. If used without parameters, the current san policy is displayed.


san [policy={onlineAll | offlineAll | offlineShared}] [noerr]


Parameter Description
policy={onlineAll|offlineAll|offlineShared}] Sets the san policy for the currently booted operating system. The san policy determines whether a newly discovered disk is brought online or remains offline, and whether it becomes read/write or remains read-only. When a disk is offline, the disk layout can be read, but no volume devices are surfaced through Plug and Play. This means that no file system can be mounted on the disk. When a disk is online, one or more volume devices are installed for the disk. The following is an explanation of each parameter:
  • onlineAll. Specifies that all newly discovered disks will be brought online and made read/write. IMPORTANT: Specifying onlineAll on a server that shares disks could lead to data corruption. Therefore, you should not set this policy if disks are shared among servers unless the server is part of a cluster.
  • offlineAll. Specifies that all newly discovered disks except the startup disk will be offline and read-only by default.
  • offlineShared. Specifies that all newly discovered disks that do not reside on a shared bus (such as SCSI and iSCSI) are brought online and made read-write. Disks that are left offline will be read-only by default.
For more information, see VDS_san_POLICY Enumeration.
noerr Used for scripting only. When an error is encountered, DiskPart continues to process commands as if the error did not occur. Without this parameter, an error causes DiskPart to exit with an error code.


To view the current policy, type:


To make all newly discovered disks, except the startup disk, offline and read-only by default, type:

san policy=offlineAll