The Data ONTAP DSM for Windows MPIO enables you to have multiple Fibre Channel (FC) and iSCSI paths between a Windows host computer and a NetApp storage system.
Note: FC support includes traditional Fibre Channel and Fibre Channel over Ethernet (FCoE). FCoE is used like traditional FC unless otherwise noted.
More information
Device-specific module overview
The Data ONTAP DSM for Windows MPIO is a device-specific module (DSM) that works with Microsoft Windows MPIO drivers (mpdev.sys, mpio.sys, and mpspfltr.sys) to manage multiple paths between NetApp and IBM N series storage systems and Windows host computers.
ALUA support and requirements
Data ONTAP uses ALUA (asymmetric logical unit access) to identify optimized paths. ALUA is required for specific configurations.
Mixing FC and iSCSI paths
The Data ONTAP DSM supports both FC and iSCSI paths to the same LUN for clustered Data ONTAP. The DSM does not support both FC and iSCSI paths to the same LUN for Data ONTAP operating in 7-Mode.
Microsoft iSCSI DSM
If you are using iSCSI to access another vendor's storage, install the Microsoft iSCSI DSM by selecting the Microsoft MPIO Multipathing Support for iSCSI check box when installing the iSCSI initiator for Windows Server 2003.
I_T and I_T_L nexus overview
An initiator-target (I_T) nexus represents the path from the host’s initiator to the storage system’s target. An initiator-target-LUN (I_T_L) nexus represents one LUN as seen by the DSM. The DSM groups all I_T_L nexuses to the same LUN together, and presents a single virtual disk to the Windows disk manager.
Multiple paths require MPIO software
If you have multiple paths between a storage system and a Windows host computer, you must have some type of MPIO software so that the Windows disk manager sees all of the paths as a single virtual disk.
Path limits
You can have a maximum of 32 paths to a LUN. This maximum applies to any mix of FC and iSCSI paths. This is a limitation of the Windows MPIO layer.
Timeout and tuning parameters overview
The Data ONTAP DSM for Windows MPIO uses a number of parameters to optimize performance and ensure correct failover and giveback behavior.
When to change the load balance policy
The Data ONTAP DSM sets the default load balance policy to Least Queue Depth. This policy provides the best method of distributing I/O to all active optimized LUN paths. Other load balance policies exist for specialized uses. Work with your application vendor to determine if another load balance policy is appropriate.
Failover examples
Examples of the failover behavior for different load balance policies demonstrate how the DSM selects active paths.
Mapping identifiers between the host and storage system
The Data ONTAP DSM for Windows MPIO includes a number of identifiers to help you map virtual disks to LUNs, and the paths (I_T_L nexuses) between the Windows host and the storage system.
Dynamic disk support
Windows dynamic disks are supported with specific configuration requirements.
What the Hyper-V Guest Utilities are
When you install Data ONTAP DSM, you can choose to install the Hyper-V Guest Utilities. You use the Hyper-V Guest Utilities to configure Hyper-V systems.
What Hyper-V is
Hyper-V is a Windows technology that enables you to create multiple virtual machines on a single physical x64 computer running Microsoft Windows Server 2008, Windows Server 2008 R2, or Windows Server 2012.
About SAN booting
SAN booting is the general term for booting a Windows host from a storage system LUN instead of an internal hard disk. The host might or might not have any hard drives installed.
Support for non-English operating system versions Data ONTAP DSM for Windows MPIO is supported on all Language Editions of Windows Server. All product interfaces and messages are displayed in English. However, all variables accept Unicode characters as input.
