Symptoms
Consider the following scenario:
In an MPIO/ALUA configuration on Windows Server 2008 and Server 2008 R2 where only non-optimized paths are available, a disk may not come online.
In an MPIO/ALUA configuration on Windows Server 2008 and Server 2008 R2 where only non-optimized paths are available, a disk may not come online.
Cause
This occurs because the default MPIO policy for ALUA capable controllers when using the Microsoft DSM is Round Robin with Subset (RRwS), and this policy does not allow a disk to come online without an optimized path being available.
Resolution
If you have a configuration where you need to function with only non-optimized paths available, use one of the following MPIO policies:
· Least Queue Depth
· Failover Only
· Weighted Paths
· Least Blocks
· Least Queue Depth
· Failover Only
· Weighted Paths
· Least Blocks
More Information
To change the default policy on Windows Server 2008 R2, use mpclaim.exe as documented in the following TechNet articles:
http://technet.microsoft.com/en-us/library/cc725907.aspx
http://technet.microsoft.com/en-us/library/ee619743(WS.10).aspx
For Windows Server 2008 you need to use a script such as the one referenced in the following post, because the version of mpclaim.exe for Windows Server 2008 does not support the commands necessary.
http://blogs.msdn.com/b/san/archive/2008/12/12/scripting-example_3a00_-how-to-set-the-mpio-lb-policy.aspx
http://technet.microsoft.com/en-us/library/cc725907.aspx
http://technet.microsoft.com/en-us/library/ee619743(WS.10).aspx
For Windows Server 2008 you need to use a script such as the one referenced in the following post, because the version of mpclaim.exe for Windows Server 2008 does not support the commands necessary.
http://blogs.msdn.com/b/san/archive/2008/12/12/scripting-example_3a00_-how-to-set-the-mpio-lb-policy.aspx