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Step 04 -- Disk Policy Configuration (SAN Policy)

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The Disk Policy

Previously referred to as "SAN Policy" in early Windows Server versions.

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. 

Windows Server defaults to OfflineShared, which is the correct setting when using Windows Server Failover Clustering (WSFC). 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 FlashArray 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 is through the use of Windows PowerShell or the DiskPart utlity. 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.

Note: This issue has been resolved in Purity//FA version 4.7.10 Long Life Release (LLR) and greater.

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 SP1, 2012, 2012 R2, 2016, or 2019 server hosting FlashArray volumes is rebooted, Windows 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 a "SCSI INQ" sent from the host.

The upgrade would change this "Product Revision" field, leading Windows Server to flag the disks associated with that volume as offline after reboot, and as a safety measure, it would require Administrator interaction before restoring connectivity. The administrator would need to open Windows Disk Management to right click on each impacted disk and manually bring them back online. In Purity//FA versions greater than 4.7.10 Long Life Release (LLR), a value of 8888 is returned as the current version into the Product Revision field, avoiding the behavior of constantly changing version numbers. Consequentially, if a disk is not set to onlineall in the Disk Policy, it will be set to offline after the next reboot. Additionally, a script has been created to set the registry values for all Disk Policies to onlineall after a server reboot. Please see Windows Reporting Drives Offline After 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 could be used 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.


Please note the following when upgrading from Purity version 4.8.8 or earlier to a later version of Purity with Clustered Windows Hosts using Clustered Shared Volumes (CSVs). 

CSVs and OfflineShared disk policy

Regarding CSVs in a Cluster and a host that did own a volume going offline for a reboot:

The Cluster Manager Service manages disk connections for the cluster. One host will always have ownership of a volume ( although usually not all on the same host). The Cluster Manager service does a heartbeat check for volumes, and when a owner host of a CSV loses its volume access, the Cluster Manager will notice and automatically find a new owner host to online the volume, without manual intervention.