The Disk is Offline Because of Policy Set by an Administrator

On a server running Windows Server 2016, an additional hard drive (not the system hard drive) connected as SAN LUN via FC may fail after each restart of the server. If you open the disk management console (diskmgmt.msc), you can see that this disk is offline.


To make the player available in Windows, right-click on the player and bring it online. You have to do this after every restart of the server. I don’t think you’ll like it.


Initially, I suspected that after a power failure in the server room, the storage systems would load later than the physical servers. However, after a smooth restart of the server, the disk also failed.

Note the Disk Manager pop-up message: Offline (disk disabled due to an administrator-defined policy).

It appears that this problem can occur in cluster failover environments or in Windows virtual machines that have randomly shared disks for multiple operating systems. This is due to the SAN policy that is new with Windows Server 2008. This policy governs the automatic assembly of external drives and is used to protect shared drives that can be accessed by multiple servers at the same time. By default, the offline sharing policy (VDS_SP_OFFLINE_SHARED) is used for all SAN drives in Windows Server. You can change the SAN policy for OnlineAll using Diskpart.

Start the command prompt as the administrator and execute the disk portion. See the current SAN policy in the context of disk :


SAN policy : General offline

Change your SAN policy:

DISKPART> san policy=OnlineAll.

DiskPart was able to change the SAN policy for the current operating system. .

Reconsider the current policy:


SAN policy : All online

Select the drive (in our example, the drive index is 2) :

DISKPART> Select Player 2

You can display their characteristics:

DISKPART> Training attributes

Make sure that the read-only attribute is not set. If this is the case, turn it off, otherwise you will see this message when you try to write something to disk: The disc is write-protected:

DISKPART> Disk attributes are write-protected

Take the disk with you:

DISCOUNT> Online Disk

DiskPart successfully bypasses the selected drive

Discs can be managed not only in Diskpart, but also with the integrated PowerShell storage module. All the way to the z. For example, to take a hard disk online, execute this command:

Set-Disk 2 -IOffline 0

Close the disk partition, restart the server and check if the disk is available after boot.

It turns out that the problem of unavailability of mapped disks is not only a problem with Windows Server, but with all versions of Windows Desktop. For example, when connecting an external USB stick or SSD under Windows 10, you can see the following status of the drive in the Device Manager (Offline – The drive is offline due to an administrator-set policy) :


Windows 10 solves the problem of offline hard drives in the same way: You need to change the SAN policy. If the drive is new, you may need to initialize it and create file system partitions on it.

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