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Disk Policy Configuration - SAN Policy

Disk Policy (aka SAN Policy)

The new Disk Policy (previously known as the SAN Policy) is the policy Windows Server uses to determine whether or not disks should automatically mount that are detected as new on the host. 

An issue has been identified in Purity//FA which cases Windows Server volumes to go offline after a Purity//FA upgrade. Following a Purity//FA Upgrade, if a Windows 2008 R2, 2008 R2 (Service Pack 1), 2012, 2012 R2 or 2016 server hosting FlashArray volumes is rebooted, Windows Server takes the volumes offline. This was due to Purity//FA returning the current version of Purity//FA in the “Product Revision” field in response to an SCSI INQ sent from the host. This lead Windows Server to mark the disks as new and to take them offline. Purity//FA now does not enter the current version into the “Product Revision” field. This issue has been fixed in Purity//FA 4.7.10, 4.8.7 and 4.9.3.

Windows Server defaults to OfflineShared which is the correct setting when using Windows Server Failover Clustering. In the case of using Windows Server as a standalone host the disk policy should be set to OnlineAll to bring existing volumes online when the host restarts.

If the Disk Policy was changed after having Pure Storage FlashArry volumes connected to a Windows Server host the new disk policy will not be applied to the previous connected volumes. The only way to update previously connected volumes (LUNs) is through the use of Windows PowerShell or DiskPart. See How to set the Partmgr Attributes registry value using PowerShell for full details. Also see Windows 2008 / 2012 Reporting Drives Offline After Server Reboots.

To check the current disk policy run the following Windows PowerShell.

Get-StorageSetting | Select-Object NewDiskPolicy

PS C:\> Get-StorageSetting | Select-Object NewDiskPolicy


To change this to the recommended setting run the following Windows PowerShell:

Set-StorageSetting -NewDiskPolicy OnlineAll


Policy Setting Effect


 All new disks are left offline by default.


 All disks on busses that are detected as internal are left offline as default.


 All disks on sharable busses, such as iSCSI, FC, or SAS are left offline by default. 

 OnlineAll (Recommended)

 All disks are automatically brought online. 


On Windows Server 2008 R2 or 2008 R2 Service Pack 1 the SAN Policy can be changed using Windows PowerShell with the following command.

"SAN Policy=OnlineAll" | diskpart 

DiskPart can be used directly with the following commands.

Microsoft DiskPart version 10.0.14393.0
Copyright (C) 1999-2013 Microsoft Corporation.
On computer: SERVER01
SAN Policy  : Offline Shared
DiskPart successfully changed the SAN policy for the current operating system.