The example provided in this section are taken from Windows Server No 3rd party DSMs are supported. A Reboot Required dialog box will be displayed after completing this configuration. Choose Yes or No depending on what other management or application tasks you are performing, but keep in mind that a reboot is required for the new MPIO Devices settings to take effect.
If iSCSI connectivity is being used, you may ignore this reboot requirement. The reason for this is to reduce the number of reboot cycles for the Windows Server host since adding iSCSI support requires an additional reboot. Click OK. You will be prompted to perform a reboot at this time. The reason for preferring PowerShell is the requirements of ensuring the device that is added adheres to the string formatting of Vendor 8 characters and Product 16 characters.
Note that if using iSCSI, please confirm that the additional adapter is present. Removing the default MPIO device is not necessary but simply a recommendation as the default Vendor 8 Product 16 device does not do anything. After the restart, open the Device Manager or the Disk Manager and make sure that the number of connected disks LUNs available to your server has reduced twice if there are two paths to your storage device. In this example, the Round Robin policy is selected for the array.
Windows has a special disk policy SAN Policy that determines whether disks must be mounted automatically when they are connected to a host. We can get the current SAN Policy setting using diskpart. Today, we saw how our Support Engineers perform this task. Never again lose customers to poor server speed! Let us help you. Your email address will not be published. Submit Comment. Or click here to learn more. When you visit any website, it may store or retrieve information on your browser, mostly in the form of cookies.
This information might be about you, your preferences or your device and is mostly used to make the site work as you expect it to. The following command will scan all devices detected by a system, find those that have multiple paths and enable MPIO support for them:.
Related Reading. Forwarding Emails to an External Address in Microsoft January 13, January 10, December 29, This driver implements only those routines necessary to interface with the storage adapter's hardware. A miniport partners with a port driver to implement a complete layer in the storage stack, as shown in Figure 2. Class drivers manage a specific device type. The class driver manages the functionality of the device.
Class drivers like port and miniport drivers are not a part of the MPIO driver package per se; however, the PnP disk class driver, disk. For more information, see the MPIO drivers sections that follow. The MPIO driver is implemented in the kernel mode of the operating system. It works in combination with the PnP Manager, the disk class driver, the port driver, the miniport driver, and a device-specific module DSM to provide full multipath functionality. Bus drivers are responsible for managing the connection between the device and the host computer.
The multipath bus driver provides a "software bus also technically termed a "root bus" "—the conceptual analog to an actual bus slot into which a device plugs. It acts as the parent bus for the multipath children disk PDOs. As a root bus, mpio. The MPIO bus driver also communicates with the rest of the operating system, and manages the PnP connection and power control between the hardware devices and the host computer, and uses WMI classes to allow storage array manufacturers to monitor and manage their storage and associated DSMs.
As explained previously in this document, a storage array manufacturer's device-specific module DSM incorporates knowledge of the manufacturer's hardware. These DSM actions are described further in the following sections.
MPIO allows for devices from different storage vendors to coexist, and be connected to the same Windows Server based system. The first DSM to claim ownership of the device is associated with that device and the remaining DSMs are not allowed a chance to press claims for that already claimed device. If the DSM does support the device, it then indicates whether the device is a new installation, or is the same device previously installed but is now visible through a new path.
In case of a failover, the DSM determines what new path should be used. The Microsoft device-specific module DSM provided as part of the complete solution in Windows Server includes support for the following policy settings:. The control panel can be used to do the following:. You can list the VID and PID for storage that is already connected to the server by using the mpclaim tool at the command prompt. Discover Multi-Paths Use this tab to run an algorithm for every device instance that is present on the system and determines if multiple instances actually represent the same Logical Unit Number LUN through different paths.
We recommend using vendor installation software to install the vendor's DSM. The report includes information on the device-specific module DSM that is being used, the number of paths, and the path state. You can also save this configuration at a command prompt by using the mpclaim command. EXE Usage examples. Before you can configure the load-balancing policy setting by using Disk Management, the device must first be claimed by MPIO.
If Path A fails, Path B is used. Select the Preferred check box, and then click OK. For a complete list of available PowerShell cmdlets in the Storage module, including usage and examples, please refer to the following TechNet site:.
You can also obtain help for individual commands by specifying the cmdlet with Get-Help, such as shown below:. In Windows 8, PowerShell modules which ship with Windows do not include help content "inbox" instead this content is provided on the Internet, and may be updated via PowerShell from a computer which has Internet access. Once a PowerShell module has been imported into the current PowerShell session, the help content may be downloaded and updated via the following command:.
Note: the —Force parameter must be used if attempting to update more than once per 24 hour period. For example, in order to obtain script examples for the Get-Disk cmdlet, the following command is utilized:. Tip: If these steps are performed prior to connecting devices of the desired BusType, you can typically avoid the need for a restart.
In most cases, the default values may be adequate; however, it may be necessary to adjust these settings to obtain optimal performance for your environment.
Scenario 1 A two-node Windows Server failover cluster is configured with multiple connections to storage for each node by using MPIO, and employs multiple active paths to maximize throughput. Due to application Service Level Agreement SLA requirements, in the event of path failures, short timeout values are required by the customer so that the resources will failover to the other cluster node more quickly.
In this case, timer values such as the PDORemovePeriod are set to a low value and then tested to ensure compliance with customer requirements. Scenario 2 A single server that is not configured as a failover cluster is configured with MPIO and multiple connections to storage to provide both increased throughput and fault tolerance of path failures.
In this case, timers such as PDORemovePeriod are increased to allow additional time for path recovery to occur.
For any customer scenario, determining the best timer values to use depends on a number of different variables, such as any of the following, which could all potentially impact whether the current settings would meet SLA or Operating Level Agreement OLA requirements:. Settings 1 through 5 in the following table can be set through the user interface. The information provided on these settings is specific to the use of Microsoft DSMs.
When using a vendor-provided DSM, refer to vendor documentation for information about the recommended timer values. Although it is possible to set the following values to a very large number, we recommend that you use caution when doing so, and that you test the values for applicability prior to using them in a production environment. If this value were applied to a setting such as PDORemovePeriod where it represents seconds , the value would equate to approximately 49, days of delay before an error would be reported.
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