UltraPath

If UltraPath is used, retain the default settings of the initiator and configure Host Access Mode and Preferred Path for HyperMetro as required. Table 6-2 lists the detailed settings.

Configuring the Local Preferred Mode

Perform the following operations to configure the local preferred mode:

1. On DeviceManager, choose Services > Hosts. Select the desired host, click on the right, and choose Modify.
   Figure 6-21 Modifying the host properties
   
   • The information displayed on the GUI may vary slightly with the product version.
   • On DeviceManager of OceanStor Dorado 6.0.1 and later versions, the icon is changed to More.

2. For the local storage system, set Host Access Mode to Asymmetric and Preferred Path for HyperMetro to Yes.
   Figure 6-22 Settings on the local storage system
   

3. For the remote storage system, set Host Access Mode to Asymmetric and Preferred Path for HyperMetro to No.
   Figure 6-23 Settings on the remote storage system
   

• For details about the Windows versions, see Huawei Storage Interoperability Navigator.
• If the storage system version is Dorado 6.1.RC3 or later, upgrade Huawei UltraPath to 31.0.0 or later.
• Before configuring HyperMetro, enable automatic LUN SN synchronization on both storage systems. If this function is not enabled, one HyperMetro LUN may be identified as two disks by host applications. For details, see section "What Can I Do If the Host Identifies One HyperMetro LUN as Two Disks?" in the HyperMetro Feature Guide for Block.

Install, configure, and use UltraPath by following instructions in the OceanStor UltraPath for Windows User Guide.

• If NPIV-enabled Windows VMs will directly access LUNs of the storage system, disable the alarm function of UltraPath after installing UltraPath.
• In a Windows server cluster, if NPIV-enabled Hyper-V VMs have been migrated (in online or fast mode) between servers, the NPIV paths managed by UltraPath will become disordered due to Windows mechanism defects. To ensure that services on Hyper-V VMs will not be interrupted, you are advised to run the upadm set npiv_strategy={ off | check | force-check | update} command to set the path detection mode to update in this scenario.

• To obtain the document, log in to Huawei's technical support website (https://support.huawei.com/enterprise/), enter UltraPath in the search box, and select the associated path to the documentation page. Then find and download the desired document. To download software, click the Software Download tab and find the desired software.
• The UltraPath version matches the storage system version. You can query the version information in the version mapping table:
  1. Log in to https://support.huawei.com/enterprise/, enter your storage model in the search box, and select the associated path to the product documentation page.
  2. Find and download the version mapping table.
  3. Query the UltraPath version in the version mapping table.

1. Set the HyperMetro working mode.

   Use either of the following methods to set the HyperMetro working mode for UltraPath:

   Method 1: Run the upadm set hypermetro workingmode=auto command to configure UltraPath to automatically adapt the HyperMetro working mode. This setting enables UltraPath to periodically query the host access mode configured on HyperMetro storage systems and adapt its HyperMetro working mode according to the host access mode.

   Method 2: Run the following command to set UltraPath to work in a fixed HyperMetro working mode:

   Command	Example
   set hypermetro workingmode=[priority | balance] primary_array_id=ID	upadm set hypermetro workingmode=priority primary_array_id=0

   The following table describes the parameters in the command.

   Parameter	Description	Default Value
   workingmode	HyperMetro working mode. priority: local preferred mode balance: load balancing mode	priority priority is recommended. balance is applicable when two active-active data centers are in the same equipment room or on the same floor.
   primary_array_id	ID of the preferred storage system. The ID is allocated by UltraPath. The storage array that is in the same data center as the application hosts reside is preferred. Run the upadm show array command to obtain the storage system ID. NOTE: In priority mode, the value of the parameter indicates the storage system to which I/Os are preferentially delivered. In balance mode, the value of the parameter indicates the storage system where the first slice section resides.	None NOTE: Mapping relationship between application hosts and storage systems: Storage system A is the preferred system for all application hosts in data center A. Storage system B is the preferred system for all application hosts in data center B.

   If you set UltraPath to automatically adapt the HyperMetro working mode, ensure that the host access mode on the storage system is consistent with that on the physical network.

2. Configure the load balancing policy.

   If HyperMetro works in load balancing mode, you can run the upadm set hypermetro loadbalancemode=[split-size | round-robin] command to configure the load balancing policy. The following table describes the parameters in the command.

   Parameter	Description	Default Value
   loadbalancemode	Load balancing policy for HyperMetro systems. split-size: slicing mode across storage systems. In this mode, UltraPath delivers I/Os to a specific storage system based on the start addresses of I/Os, slice size, and preferred storage system. For example, if the slice size is 128 MB, the I/Os whose start addresses range from 0 to 128 MB (excluding 128 MB) are preferentially delivered to the preferred storage system and the I/Os whose start addresses range from 128 MB to 256 MB (excluding 256 MB) are delivered to the non-preferred storage system. The default slice size is 128 MB. You can run the upadm set hypermetro split_size command to change it. round-robin: round-robin mode across storage systems. In this mode, UltraPath selects two storage systems in turn to deliver I/Os.	split-size

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? and How Do I Modify the iSCSI Initiator's Driver Timeout Time?, thereby shortening I/O interruption.