What's New in Microsoft Multipath I/O (for r2 only)

A growing number of organizations require that their data be available at all times. To meet this requirement, centralized storage must be readily available and immune to outages. Multipathing is the ability of a system to use more than one read/write path to a storage device. It is a solution that provides fault tolerance against a single point-of-failure in hardware components.
The Microsoft® Multipath I/O (MPIO) framework helps ensure that your data is available at all times. MPIO supports multiple data paths to storage, improves the fault tolerance of the storage connection, and in some cases, provides greater aggregate throughput by using multiple paths at the same time. This helps improve system and application performance.

What are the major changes?

The following changes to MPIO are available in Windows Server® 2008 R2:

• MPIO health reporting
  
  The improved MPIO health model enables IT administrators to more efficiently diagnose and gather information about path health by capturing statistical information that can be reviewed in real time or collected over time for trend analysis. This feature calculates how long paths are down, and it detects inconsistent failovers. MPIO health reporting uses a collection of statistics that are provided through Windows® Management Instrumentation (WMI) classes. It enables quicker root-cause diagnosis for a failover issue on a server that is connected to external storage through multiple paths.
  
• Enhanced configuration of MPIO load-balance policies
  
  You can display and configure load-balance policy settings from the command line by using the MPCLAIM utility. This utility makes configuration of MPIO easier, including scripting the new Least Blocks MPIO load balance policy, and MPCLAIM enhancements that allow you to more easily script the configuration of MPIO. It also gives you the ability to configure load balance policies per disk from the command line, or configure global policies that will be applied to all new MPIO disks.
  
• MPIO configuration reporting
  
  The MPIO configuration report can be saved as a text file, which makes it easier to show important information such as the Device Specific Module (DSM) file that is in use for a specific device, the number of paths, and the paths' states. You can review the text file for troubleshooting or comparison purposes at a later time.
  
• MPIO datacenter automation
  
  MPIO datacenter automation allows IT administrators to configure MPIO settings prior to connecting a storage device. To minimize the configuration that is needed after the storage device is connected, you can preconfigure settings such as the default load-balance policy.