OS Native Multipathing Software

If the OS native multipathing software is used, you must select Use third-party multipath software for the initiator, as shown in Figure 6-5.

Figure 6-5 Using OS native multipathing software

The Switchover Mode and Path Type depend on the actual services. Different models of Huawei storage systems support different ALUA policies. For details, refer to the specific Huawei storage model's product documentation.

For details about the Windows versions, see the Huawei Storage Interoperability Navigator.

If a LUN has been mapped to the host, you must restart the host for the configuration to take effect after you modify the initiator parameters. If you configure the initiator for the first time, restart is not needed.

Unless otherwise specified, the recommended configurations for Huawei storage that supports ALUA are detailed as follows:

ALUA Configuration on Old-Version Storage

Table 6-4 ALUA configuration on old-version storage

Server OS	ALUA Enabled or Disabled on the Storage System			Remarks
	OceanStor T V1	OceanStor T V2	Other Version
Windows Server 2003	Enabled	Enabled	Disabled	-
Windows Server 2003 R2	Enabled	Enabled	Disabled	-
Windows Server 2008	Enabled	Enabled	Disabled	Optimal path selection fails on Windows Server 2008 and Windows Server 2008 SP2 even after ALUA is enabled. You must set optimal paths manually.
Windows Server 2008 R2	Enabled	Enabled	Disabled
Windows Server 2012	Enabled	Enabled	Disabled	-

You are advised to enable ALUA on OceanStor T V1 because mirror link interruption may interrupt services if ALUA is disabled.

As a built-in service in Windows, MPIO is disabled by default. You need to manually enable it. Moreover, ALUA must be configured on storage systems as required.

This section uses Windows Server 2012 R2 as an example to describe how to install and configure MPIO. The MPIO installation and configuration procedures are the same as these for Windows Server 2012 R2 and therefore will not be detailed. For more details, see the Microsoft official documentation.

1. Add Multipath I/O.

   Start Server Manager, choose Manage > Add Roles and Features, and select Multipath I/O, as shown in Figure 6-6.

   Figure 6-6 Adding Multipath I/O
   

2. Query the device's VID and PID.

   VID indicates the vendor ID, for example, HUAWEI.

   PID indicates the product ID, for example, S5500T, S5600T, or XSG1.

   If MPIO is installed on Windows Server 2008 or later versions, you can use multipathing command mpclaim to query disk information, as shown in Figure 6-7.

   Figure 6-7 Querying disk information
   

   In the preceding figure, the VID is HUAWEI and the PID is XSG1.

   The PID and VID in this section are examples only.

3. Configure MPIO to take over the storage system.

   You can add the target storage system on the MPIO console or run a command in Command Prompt to take over the storage. In this example, a command is run in Command Prompt.

   On the Windows server, open Command Prompt and run the mpclaim -r -i -d "HUAWEI XSG1 " command, as shown in Figure 6-8. Note that the VID must contain eight characters and the PID must contain 16 characters. If the characters are insufficient, add spaces. You can copy the VID and PID from the output of the mpclaim -e command.

   Figure 6-8 Taking over Huawei storage
   

   After the mpclaim -r -i -d "HUAWEI XSG1 " command is executed, the host restarts automatically. If the host does not restart automatically, restart it manually.

4. View MPIO policies.

   Rescan for disks after restarting the host. Ensure that the number of discovered disks is consistent with that of LUNs mapped to the host. Right-click a disk and choose Properties from the shortcut menu. You can view the policies on the MPIO tab page, as shown in Figure 6-9.

   Figure 6-9 MPIO policy management page
   

   Normally, the default MPIO policy is preferred. The default policy varies with operating system configurations. Table 6-6 lists the default policies for commonly used operating systems.

   Table 6-6 Default MPIO policy

   Operating System	Storage System	Default MPIO Policy	Remarks
   Windows Server 2008	ALUA enabled	Round Robin with Subset	-
   	ALUA disabled	Failover only	-
   Windows Server 2008 R2	ALUA enabled	Round Robin with Subset	-
   	ALUA disabled	Round Robin	-
   Windows Server 2012	ALUA enabled	Round Robin with Subset	-
   	ALUA disabled	Round Robin	-
   Windows Server 2012 R2	ALUA enabled	Round Robin with Subset	-
   	ALUA disabled	Round Robin	-
   Windows Server 2016	ALUA enabled	Round Robin with Subset	-
   	ALUA disabled	Round Robin	-
   Windows Server 2019	ALUA enabled	Round Robin With Subset	-
   	ALUA disabled	Round Robin	-

5. Enable path verification.

   On the MPIO tab, click Details. In the dialog box that is displayed, select Path Verify Enabled and click OK. Then restart the host for the configuration to take effect.

   Figure 6-10 Enabling path verification
   
   • If a path switchover takes a long period of time, you can modify the timeout time for a driver by following instructions in How Do I Modify the Timeout Time for the FC HBA Port Driver?, How Do I Modify the iSCSI Initiator's Driver Timeout Time?, and How Do I Change the Number of TCP Data Retransmission Times? to shorten I/O interruption.
   • If the underlying physical signals between the storage system and Cisco switch are poor, the Cisco switch resets the link. There is a low probability that the Cisco switch does not detect the port status change and does not send RSCN messages. In this case, Windows MPIO cannot detect the port status change, and host services are interrupted due to I/O retry timeout on an abnormal link. Huawei UltraPath can be used to avoid this risk.

Run the mpclaim -s -d command to verify that the configuration has taken effect.

Figure 6-11 Verifying the MPIO disk information

Run the mpclaim -s -d MPIO Disk No. command to verify path information about an MPIO disk.

Figure 6-12 Verifying path information about an MPIO disk

Both AO (whose TPG_State is Active/Optimized) and AN (whose TPG_State is Active/Unoptimized) paths are displayed, indicating that ALUA configuration has taken effect.