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iSCSI! 

Posted By:  Adam Bomb 
Publish Date: 1/17/2008


I’ve been doing Windows Clustering since back when we used to call it Wolfpack. Clustering is cool, but it can be painful to get it all up and running. Most of that pain often comes from trying to get the shared nothing storage configured properly, which in the old days meant sorting out all your SCSI IDs for all the devices, or making sure your fiber channel optic cables were clean and connected.

Fortunately, network speeds today are such that we can ease some of that pain by moving the storage connections to Ethernet. That process is made really easy by using iSCSI protocols, which are built in to Vista and Server 2008, and have been available as downloads for XP and Server 2003.

iSCSI Q&A

What does it do? Very simply, iSCSI takes commands or requests that the OS would make to a local hard disk, and sends them over the network to a storage array or other target. Disks look like local disks on your machine – you can see them in Disk Management, format them, partition them, etc., but they physically reside as files on the network.

What are the components? There are two: the iSCSI Initiator is the app that you run on your client to make the initial connection to the remote disk. This is included by default in Vista and Windows Server 2008· an iSCSI Target runs on the storage that you’re connecting to. One is typically available for SAN or NAS hardware, and we include one in Windows Storage Server SKU’s. The iSCSI Target lets you configure what disks are available to connect to, and what machines are allowed to connect.

How do I do it? It’s actually really cool: Set up an iSCSI Target. You have a few options. If you have a Windows Storage Server with the Windows Unified Data Storage Server add on (WUDSS), It includes a console that lets you configure iSCSI. There are also a few 3rd party iSCSI Target apps you can install on Windows Server.· Configure your iSCSI Disks. On Storage Server, you create some .vhd files, specifying the size. Note that these are just virtual disks, not whole machine images.· Configure which machines can connect to the iSCSI disks, and any security you want to put in place (you can require that the connection to the target use IPSec, for example)· Run the iSCSI initiator from the machines you want to make the storage available on. Connect to the Target, specify which disks you want to connect to, and the disks will show up in Disk Management, where you can assign them drive letters, partition them, etc.

Why would I want to do this, again?· It makes Failover Clustering much, much easier. You can get real failover clustering running in an afternoon on a couple of laptops, if you wanted to. · In an Enterprise environment, you can easily leverage centralized storage without a capital investment in specialized storage equipment.Get startedWindows Storage Server is normally available as part of an OEM storage device, but you can download an eval version if you want to take a look. Details are available on the Storage Solutions website, and you can register for eval downloads here. (make sure you select WUDSS to get access to the iSCSI Target components)There are also a few companies that make iSCSI Targets for Windows. Nimbus, Rocket Division and String Bean are a few of them (disclaimer: I haven’t worked with any of these products and can’t speak to their performance, reliability or support).