What is iSCSI?
Internet Small Computer Systems Interface (iSCSI) is a storage networking standard that allows servers to access block-level storage over a standard TCP/IP network. Unlike a traditional file share (SMB/NFS) where the server handles the file system, an iSCSI disk appears to the client machine as a raw, physical hard drive attached directly to the motherboard. In an iSCSI architecture, the Target is the server hosting the storage, and the Initiator is the client computer consuming it.
Step 1: Install the iSCSI Target Role
Log in to the Windows Server that will host the storage. Open Server Manager and launch the Add roles and features wizard. Expand File and Storage Services > File and iSCSI Services, and check the box for iSCSI Target Server. Complete the installation.
Step 2: Create an iSCSI Virtual Disk
Once installed, open the Server Manager and navigate to File and Storage Services in the left pane, then click on iSCSI.
Click the link to “To create an iSCSI virtual disk, start the New iSCSI Virtual Disk Wizard.” Select the physical volume on your server where the virtual disk file (a .vhdx file) will be saved. Give the virtual disk a name (e.g., SQL-Data-Disk) and define its size (e.g., 500 GB). You can choose between a dynamically expanding or fixed-size disk.
Step 3: Create the iSCSI Target
As you proceed through the wizard, you will be prompted to assign the virtual disk to an iSCSI Target. Select New iSCSI Target and give it a name (e.g., SQL-Target).
On the Access Servers page, you must specify which client machines are allowed to connect. Click Add…. The most secure method is to specify the exact IQN (iSCSI Qualified Name) or the IP Address of the Initiator (client) server. Click Next, optionally configure CHAP authentication for extra security, and hit Create.
Step 4: Connect the Initiator
Now, log in to the client server (the machine that needs the storage). Click the Start button, type iSCSI Initiator, and open the built-in Windows utility. If prompted that the Microsoft iSCSI service is not running, click Yes to start it automatically.
In the Targets tab, enter the IP address of your iSCSI Target server in the “Target:” box and click Quick Connect. Your target name (e.g., SQL-Target) should appear in the list with a status of “Connected.”
Step 5: Initialize the New Disk
The client server now has a new physical disk attached to it. Open Disk Management (diskmgmt.msc) on the client server. You will see a new disk listed as “Offline.”
Right-click the disk name, select Online, then right-click again and select Initialize Disk. You can now format it with NTFS or ReFS and assign it a drive letter. To applications running on the client server, this network storage behaves exactly like a locally installed hard drive.