HP P2000 HP StorageWorks P2000 G3 MSA System MPIO DSM Installation Guide (5903 - Page 20

Long Failover Times When Using MPIO with Large Numbers of LUNs • Microsoft Windows servers running MPIO use a default Windows Registry PDORemovePeriod setting of 20 seconds. When MPIO is used with a large number of LUNs, this setting can be too brief, causing long failover times that can adversely affect applications. The Microsoft Technical Bulletin Configuring MPIO Timers, describes the PDORemovePeriod setting: "This setting controls the amount of time (in seconds) that the multipath pseudo-LUN will continue to remain in system memory, even after losing all paths to the device. When this timer value is exceeded, pending I/O operations will be failed, and the failure is exposed to the application rather than attempting to continue to recover active paths. This timer is specified in seconds. The default is 20 seconds. The max allowed is MAXULONG." Workaround: For both Windows 2003 Server and Windows 2008 Server, if you are using MPIO with a large number of LUNs, edit your registry settings so that HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\mpio\Parameters\PDOR emovePeriod is set to a higher value. • If you are using a Fibre Channel connection to a Windows server running MPIO, use a value of 90 seconds. • If you are using an iSCSI connection to a Windows server running MPIO, use a value of 300 seconds. For more information, refer to Configuring MPIO Timers at: http://technet.microsoft.com/en-us/library/ee619749%28WS.10%29.aspx 20