Data Centers

DIY SAN: Windows Server 2012 Storage Spaces and iSCSI target

John Joyner shows you how to use Windows Server 2012 to create an iSCSI target and virtual disk that can be used for storage.

Windows Server 2012 is a jack-of-all-trades when it comes to storage, and it can save you a lot of money. There are exciting and totally new features like Storage Spaces that aggregate storage across drives and disk controllers. Another valuable file server feature is now built into Windows Server 2012 — that is the ability to define an iSCSI target on the Windows Server, essentially turning the server into a "SAN head". Provisioning a Windows Server 2012 computer with lots of inexpensive storage can be a low cost route to a highly available SAN.

A new option for server-based storage entered the market in April, 2011 when Microsoft made available for free public download a software package that transforms a standard Windows Server 2008 R2 computer into a Windows Storage Server, aka an iSCSI SAN provider. An iSCSI target server and supporting features are now bundled with Windows Server 2012, making it even easier to get the most out of your production, backup, or lab storage resources. Figure A shows the File and iSCSI Services selected in the Windows Server 2012 Add Roles and Features Wizard.

Figure A

Windows Server 2012 File and Storage Services installed via Server Manager

Preparing the iSCSI target server

For production deployments, a dedicated iSCSI network for storage traffic is usually indicated. In enterprise scenarios, prepare a network interface card (NIC) or NIC team to use for iSCSI traffic alone. In demonstration and lab settings, as well as converged networks running at 10GBPS or faster, you can use the same NIC used by the operating system for network traffic.

Of course, the iSCSI Target server should be provisioning with lots of local or direct-attached storage to share out as SAN-based disks to other computers on the iSCSI network. With Windows Server 2012, there is the option to create a Storage Space, a pooled model for managing local and direct attached storage. Storage Spaces maintains the health of these drives and any redundancy selected.

Create a Storage Pool, Virtual Hard Disk, and Volume

The scenario is presenting three (3) 931-GB SATA hard disks over the network in a fault-tolerant manner via iSCSI to a DPM server. The iSCSI client (initiator) feature on the DPM server will view the storage as local or directly attached. DPM can use a volume in this storage for backup of other servers and applications. The business objective is to efficiently use storage that already exists on the network, without for example, growing a conventional SAN.

Follow these steps to create a storage pool and a virtual disk to be used for iSCSI storage:

1.      In the Windows Server 2012 Server Manager, navigate to File and Storage Services | Volumes | Storage Pools. Click Tasks | New Storage Pool. This launches the Storage Pool Wizard. 2.      Name the storage pool and select the group of available raw disks (also known as a primordial pool) to use. Figure B shows the option to select and modify physical disk allocation. Unless you want to manually specify one or more hot spare disks, leave the disk allocation type set to Automatic.

Figure B

Select physical disks to include in the storage pool

3.      Proceed to create virtual disks after completing the Storage Pool Wizard. The New Virtual Disk Wizard will launch.

4.      Select the storage pool created in step 2 and name the volume. In this application, the volume is going to be presented to a System Center Data Protection Manager (DPM) server, so the name "DPM iSCSI Storage" will be used.

5.      Select either Simple, Mirror, or Parity storage layout. Since this storage space in this environment includes three (3) or more hard disks, the parity type is a good choice.

6.      Next select either Thin or Static (Thick) provisioning for the volume. These settings are similar to Dynamic and Fixed virtual hard disks-however this setting is at the aggregate volume level of the storage pool. For DPM, Static provisioning is highly recommended.

7.      Specify the size of the virtual disk. If using thin provisioning, the size can be greater than the free space in the storage pool. For this DPM backup volume application, the option to create the maximum size volume using all the disk space was selected.

8.      Figure C shows the confirm selections page, ready to create the virtual disk inside the storage pool. Click Create to continue.

Figure C

Creating a virtual disk inside the storage pool

9.      Proceed to create a new volume after completing the New Virtual Disk Wizard. The New Volume Wizard will launch.

10.   Confirm the server, select the disk created in step 4, select a volume size, and assign a drive letter (if any) for the new volume. For the DPM backup volume, this demonstration is using all the available space and assigning the drive letter "R:".

11.   Name the volume and as shown in Figure D, optionally enable data deduplication. (Windows Server 2012 data deduplication delivers optimization ratios of 2:1 for general file servers and up to 20:1 for virtualization data.)

12.   Confirm the new volume settings and create the volume.

Figure D

Optionally enable data duplication on the new volume

Create an iSCSI Virtual Disk

Now that a volume is prepared (in this demonstration, a 2.73-TB "R:" drive on the storage server), you can create an iSCSI virtual hard disk (VHD) on the volume and present it to iSCSI clients. Follow these steps to create an iSCSI virtual disk:

  1. In the Windows Server 2012 Server Manager, navigate to File and Storage Services | iSCSI. Click Tasks | New iSCSI Virtual Disk. This launches the New iSCSI Virtual Disk Wizard.
  2. Select the volume created previously ("R:" drive in this demonstration), name the VHD, and select the VHD size, up to the maximum usable space on the volume. Tip: This should be a bit smaller than the volume size to avoid "low disk" alerts.
  3. Select to create a New iSCSI Target and provide a name. This name will be discovered by the iSCSI initiator, and used for the connection.
  4. Add the initiator ID—if the iSCSI client is a Windows Server 2012 computer in the domain, you can query active directory for the initiator query name (IQN). An example IQN is iqn.1991-05.com.microsoft:server.domain.com.
  5. Confirm the new iSCSI virtual disk settings and create the disk.
The iSCSI target and virtual disk are ready to use for production or other purposes. With the iSCSI Initiator applet on any networked iSCSI client computer (such as the DPM server this iSCSI disk was prepared for) you can connect to the new iSCSI virtual disk and start using the storage.

About

John Joyner, MCSE, CMSP, MVP Cloud and Datacenter Management, is senior architect at ClearPointe, a cloud provider of systems management services. He is co-author of the "System Center Operations Manager: Unleashed" book series from Sams Publishing, ...

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