Ouch….If you run Clustering and Hyper-V you understand about MPIO and Many LUNs

This just passed my RSS feed from a great resource Aidan Finn, who originally got the info from Tim Berk.

 

Have a read over this and make sure you have these hotfixes on your Cluster Boxes.

From Adian Blog

May 29

Windows Server 2008 SP2 and MPIO

Tim Berk brought our attention to a couple of hotfixes for SP2 on Windows 2008 that will be relevant if you are using MPIO (dual path attached storage) for Windows Server 2008 servers.

KB967752: A Windows Server 2008-based computer that is connected to a storage device over MPIO paths does not restart

  • Consider the following scenario:
  • You are running a Windows Server 2008-based computer that is connected to a storage device over some Microsoft Multipath I/O (MPIO) paths.
  • A Microsoft MPIO Device Specific Module is enabled for these MPIO paths.
  • The storage device is configured as an iSCSI boot device or a Storage Area Network (SAN) boot device.
  • You install and then uninstall Windows Server 2008 Service Pack 2.
  • You have installed hotfix 957316 on the Windows Server 2008-based computer.

In this scenario, the computer does not restart if the storage device is a boot device, or you lose access to the device if the device is a data volume.

KB957316: Disk I/O errors occur after you restore a failed MPIO path on a Windows Server 2008-based computer

Consider the following scenario:

  • You are running a Windows Server 2008-based computer that is connected to a storage device over some Microsoft Multipath I/O (MPIO) paths.
  • A Microsoft MPIO Device Specific Module is enabled for these MPIO paths.
  • A heavy load occurs on the storage device.
  • One of the MPIO paths fails. Therefore, some logical unit numbers (LUNs) fail over to another MPIO path.
  • You restore the failed MPIO path.
  • The computer tries to access the storage device.

In this scenario, disk I/O errors occur. This problem is more likely to occur when there are many LUNs.

Booting from and storing data on MPIO attached storage is becoming more and more common, e.g. blade servers and SAN.  Make sure you are covered in these scenarios, especially if using something like WSUS or Configuration Manager to deploy service packs.

Credit: Tim Berk.

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