On one of the servers working Windows Server 2016, an extra disk (not a system one) related as a SAN LUN over FC will get offline after every restart of the server. If you open Disk Management console (diskmgmt.msc), you possibly can see that this disk is in Offline state.
To make the disk accessible in Windows, right-click it and take it on-line. You should do it after every server restart. I don’t assume you’re proud of that.
First of all, I suspected that after an influence outage within the server room, the storage techniques booted later than the bodily server. However, after a smooth server reboot the disk went offline as properly.
Note the popup message a couple of disconnected disk within the Disk Management:
Offline (The disk is offline as a result of of coverage set by an administrator).
As it turned out, this drawback could seem within the failover cluster environments or digital machines working Windows which have any shared disks might be accessed by a number of working techniques. It is associated to the SAN Policy that appeared in Windows Server 2008. This coverage controls computerized mounting of exterior disks and is used to guard shared disks accessible to a number of servers directly. By default, the Offline Shared (VDS_SP_OFFLINE_SHARED) coverage is used for all SAN disks on Windows Server. You can change your SAN Policy to OnlineAll utilizing Diskpart.
Run the command immediate as administrator and run the
diskpart. In diskpart context, show the present SAN coverage:
SAN Policy : Offline Shared
Change your SAN Policy:
DISKPART> san coverage=OnlineAll
DiskHalf efficiently modified the SAN coverage for the present working system.
View the present coverage once more:
SAN Policy : Online All
Select your disk (in our instance, the disk index is 2):
DISKPART> choose disk 2
You can view its attributes:
DISKPART> attributes disk
Make positive that the Read-Only attribute is not enabled. If it is, disable it, in any other case when making an attempt to put in writing one thing on the disk, you will note this message: :
DISKPART> attributes disk clear readonly
Take the disk on-line:
DISKPART> on-line disk
DiskHalf efficiently onlined the chosen disk
Set-Disk 2 -IsOffline zero
Close diskpart, restart your server and ensure that the disk is accessible after boot.
It turned out that the issue of unavailability of related disks is typical not just for Windows Server, but additionally for all desktop Windows variations. For instance, for those who join an exterior USB drive or an SSD in Windows 10, you may as well see the next disk standing (Offline – The disk is offline as a result of of coverage set by an administrator) within the Device Manager:
In Windows 10, the difficulty with the offline disks is solved in the identical method: you have to change the SAN coverage. If the disk is new, you could have to initialize it and create file system partitions on it.