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NetApp SAN Boot with Windows

Thoughts and ideas concerning booting from SAN when we attempted this with our NetApp array.

  1. SAN Boot is fully supported by MSFT.  The first thing that happened is that we were told that SAN boot is not supported and we could not get Microsoft support for this configuration.  It turns out that this is not correct.  SAN boot is fully support by Microsoft along with HW partners like NetApp.  This TechNet article fully outlines MSFT’s support for SAN Boot:  http://support.microsoft.com/kb/305547
  2. Zoning is the #1 issue with SAN Boot on FC. In talking with NetApp support team (who were a HUGE help on this issue) the most common issue in SAN Boot from Fiber Channel is zoning.  Because zoning can be complex, this is the most likely cause of error.  We strongly recommend you check and then double-check your zoning before opening a support ticket.   In our case, the zoning for the server was correct, but we did make a zoning error on another server that we were able to correct on our own.
  3. Windows MPIO support at install time is limited. Because WinPE is not MPIO aware, there can be strange results when deploying against a LUN that is visible via multiple paths.  Keep in mind that at install time, Windows boots to boot.wim which is running WinPE instead of a full Windows install.  After the bits are copied locally, windows reboots to complete the install and at this time Windows is actually running.  Because of this, NetApp support team recommends having only one path to the LUN at install time and then adding paths later once Windows is up and running and you can enable Windows MPIO.
  4. AND YET…  MPIO is strongly recommended for SAN Boot.  Because a Windows host will blue screen if it’s boot lun dies, MPIO is strongly recommended for boot LUNs.  This is documented here:  http://technet.microsoft.com/en-us/library/cc786214(WS.10).aspx.  This can seem contradictory at first, but the bottom line is that MPIO is good, just add it later once Windows is up and running correctly.
  5. Yes, but what about Sysprep?  It turns out that MPIO is not supported for Sysprep based deployments:  http://support.microsoft.com/kb/2504934.  So, again you need to configure MPIO post deployment when you are deploying against sysprep’d images.  In the case of NetApp, we strongly recommend using Sysprep boot LUNS which you can then clone for new machines.  This significantly shortens deployment time as opposed to doing a full Windows install for each new host.
  6. It’s all about BIOS. Actually installing windows on a boot LUN does require that Windows Setup sees your target LUN as a valid install path.  This means that the server must report this drive as a valid install target or Setup will not let you select this disk.  For FC, you will need to enable the BIOS setting and select your target LUN in the HBA setup screen.  This process varies by vendor.  Then you need to make this disk your #1 boot target in your server’s BIOS.  Again, this process varies by manufacturer.  As noted above, you should only establish one path.  This includes dual port HBA’s.  Only configure one of the ports.
  7. Where’s my disk? Once you do all the above correctly, Setup may still refuse to show you the disk.  This could be because the correct driver is not present on the install media.  One way to fix this is to inject drivers into your Boot.WIM and Install.WIM.  This process is required if you are using WDS but optional if you are hand building a server from DVD or ISO.  In our case, we were building a single master image that we were going to Sysprep so we simply inserted the media and added the drivers manually during setup.
  8. OK, the disk is there, but I can’t install! One funny thing about Windows setup is that if you are installing from DVD, that DVD must be present to install (duh).  This is fine, unless you used the process above to insert the driver.  To do this, you need to remove the disk.  Then you get the drives and click install.  Windows will fail to install with a fairly obtuse error.  You need to remove the drivers DVD at this point and put the install DVD back in.  Seems obvious, but it took me a few minutes to figure out what was wrong the first time I tried it.

The Windows Host Utilities Installation and Setup Guide (http://now.netapp.com/NOW/knowledge/docs/hba/win/relwinhu53/pdfs/setup.pdf) has a very detailed description of Windows support for FC LUNs and there is a step by step process in this guide for configuring Boot LUNs.

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