EMC Solution Brief - Configuring Boot from SAN with an EMC VNX or CLARiiON
Note: This content applies to EOL equipment though the concepts are still relevant to newer Dell-EMC SANs such as Unity, ME4, and PowerStore. The MPIO procedure has not changed much in Windows 2012-Windows 2019 either.
Storage Support | Boot from SAN
Once the operating system is loaded (in this case, Microsoft Windows 2008 R2 Server Enterprise), you will want to enable MPIO (Multi-Path IO) Support if you have a dual port HBA or two HBAs. Microsoft's MPIO role is very easy to manage and fairly powerful, though you may want to consider using EMC's PowerPath software for MPIO especially if you have mixed OS environments. This is a topic for another blog post, though.
If you have two (or more) paths to your LUNs, the Windows Disk Manager will show them like below. Notice how only one disk is online, but both "disks" are actually pointing to the same LUN:
We are using an older CLARiiON CX300 which will require FLARE 26 for Microsoft's MPIO to work. Earlier FLARE revisions were not SPC-3 compliant with Active / Active ALUA (Asynchronous Logical Unit Access) which is mandatory for Microsoft's MPIO operation without an EMC DSM (Device Specific Module.) Any modern VNX5300, VNX5500, or VNX5700 storage processor will be running FLARE revisions much newer than this anyway.
You will want to make sure the driver for your HBA is up to date. With older Q-Logic Adapters such as the QLA2342, Windows usually has the latest driver already available. However, on newer HBAs, the first thing you will want to do is obtain the latest driver from the vendor website (or from EMC.) I have noticed with Emulex adapters (notably the LP11002 4Gb) enabling MPIO on stock Windows 2008 drivers can result in a Blue Screen of Death at startup.
After the driver is up to date, you will need to install Microsoft MPIO support which is not part of the standard installation. First, enter the server (computer) management console.
Select 'Features' from the left column and click "Add Features" in the right column. Proceed through the feature installation wizard and select "MultiPath I/O." You will probably need to restart your server when the installation completes.
After installation, start the Microsoft MPIO Utility:
When you enter the MPIO utility, you should see a screen similar to the left half of the image below (MPIO Devices Tab.) If you do not see a device listed, make sure your initiator record for this server is properly configured as "CLARiiON Open" with ALUA-4 (Active / Active) under Unisphere. Next select the Discover-Multi-Paths tab and select the DGC RAID 5 device and click "Add." If you do not see your EMC CLARiiON or VNX array here, make sure your HBA driver is Windows 2008 MPIO compatible. You will need to restart your server again for the changes to take affect.
When the server restarts, go back to the Server Manager and select "Disk Management" under the "Storage" Group on the left column. You should see only one instance of your SAN Boot LUN. If you right click on it, and select the MPIO tab, your screen should look like the image below:
Here you can select the load balancing and failover algorithms. This tutorial was based on a very simplistic failover model. Round Robin algorithms distribute the I/O activity over HBAs and Ports to optimize performance. Round Robin is the default algorithm selection in Windows 2008. However, with our setup, there is only one active path (notice only one Active / Optimized path is listed.) Data will only traverse an Active / Optimized path. As such, the Round Robin algorithm operates like the "Failover Only" algorithm though there are differences depending on the storage system settings. An Active / Unoptimized path is a standby path that can be made "optimized" on a moment's notice via SPC-3 compliant protocols that the MPIO driver and FLARE adhere to. As such, no load balancing will occur. This is because one of our paths is going to EMC SPA and the other path is going to EMC SPB. Only ONE storage processor can talk to a LUN at a time. In a later tutorial, we will demonstrate how to create two Active / Optimized paths by changing the Brocade Zoning settings. However, you should be able to unplug the LC fibre cable from any one of the HBA ports and not experience downtime. (10 seconds of lag may occur, but applications should not crash and the server will most certainly not reboot.) You may want to read up on ALUA, SPC-3 compliance, and LUN trespassing to better understand the MPIO policy options.
You may want to install your HBA's Management Utility to verify physical link status to your SAN periodically. Q-Logic has a great utility called SanSurfer that lets you update firmware, configure persistent binding, view paths, and perform many other SAN related tasks. If you have an Emulex adapter, consider the OneCommand manager.
When you enter SanSurfer, you can select to manage either the local machine or any machine on your IP network that has the SanSurfer agent installed. The first screen you see should look like the image below. Notice how SanSurfer detects that you have redundant paths to your LUN via the two grey lines. You can also see the same Disk ID DID [LUN(0)] under each port.
Note: As you fool around with QLogic SanSurfer options, the default Administrator password is "config."
That's it! You should not be able to boot Windows 2008 R2 from a SAN without having any internal disk drives. Your connection should be redundant in case any cable, switch, or Service Processor fails or undergoes maintenance. We will post more mini-tutorials such as this to show how you can use newer EMC VNXe3100 and VNXe3300 iSCSI SANs to accomplish the same SAN boot with a different fabric.