OS Native Multipathing Software
Storage System Configuration
If you use OS native multipathing software, you must select Uses third-party multipath software for the initiator and set the Switchover Mode to Special mode, as shown in Figure 6-14.
The Switchover Mode and Path Type depend on the actual services, as described in Table 6-10.
Server OS |
HyperMetro Working Mode |
Storage Array |
OS Setting |
Third-Party Multipathing Software |
Switchover Mode |
Special Mode |
Path Type |
|---|---|---|---|---|---|---|---|
AIX |
Load balancing |
Local |
AIX |
Enabled |
Special mode |
Mode 1 |
Optimal |
Remote |
AIX |
Enabled |
Special mode |
Mode 1 |
Optimal |
||
Local preferred |
Local |
AIX |
Enabled |
Special mode |
Mode 2 |
Optimal |
|
Remote |
AIX |
Enabled |
Special mode |
Mode 2 |
Non-optimal |
- For details about the AIX 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.
- To change the LUN mapping on the storage system, including but not limited to changing the host LUN ID, changing the port online, and removing and adding a LUN, follow the instructions in How Can I Change LUN Mappings When Non-Huawei Multipathing Software Is Used? to correctly change the LUN mapping. Otherwise, services may be interrupted.
In OceanStor V3 V300R003C20, mode 1 and mode 2 are disabled by default. For details about how to enable them, see the OceanStor 5300 V3&5500 V3&5600 V3&5800 V3&6800 V3 Storage System V300R003C20 Restricted Command Reference or OceanStor 18500 V3&18800 V3 Storage System V300R003C20 Restricted Command Reference. Contact Huawei technical support engineers to obtain the documents.
Host Configuration
Operating Environment Requirements
- In SAN Boot mode, the virtual LUN running the host's operating system must be a common virtual LUN. You can change a common virtual LUN to a HyperMetro virtual LUN only after ODM is installed on the host and the host is restarted.
- When NPIV coupled with VIOS is used, the requirements of NPIV on hardware and software must be met.
Installing and Enabling Multipathing Software
AIX native MPIO can take over Huawei storage disks only if the AIX ODM package has been installed. For details on how to install AIX ODM, see the AIX ODM for MPIO User Guide.
Run the lsdev -Cc disk command to verify that MPIO has taken over the disks from Huawei storage. Figure 6-15 is an example.
Before checking MPIO takeover, run the cfgmgr -v command to scan LUNs.
Configuring Multipathing Software
After the switchover mode for the initiators on the storage arrays is set to Special mode, the default I/O policy is fail_over. I/Os can be delivered only on one path. To deliver I/Os to the paths of both active-active arrays, run the command in Figure 6-16 to change the I/O policy to round_robin. In AIX 6.1 TL9 and later or AIX 7.1 TL3 and later, if the disk type is not SCSI-2 reserves, use the shortest_queue path selection algorithm to maximize SAN resource usage. When the load is light, the shortest_queue algorithm is similar to the round_robin algorithm. Once a path is congested, the system automatically allocates more I/Os to other lightly loaded paths.
When AIX native MPIO is used, services must be suspended before you change the I/O policy for hdisk.
Verification
After I/Os are delivered, run the following command to check whether the path priority is correct.
If the value of path_status has Opt, the corresponding paths are preferred ones. Other paths are non-preferred ones.
In the example shown in Figure 6-17, there are two preferred paths and 10 non-preferred paths. The result is the same as configured, indicating that the configuration is successful.
Only AIX 6.1 TL9, AIX 7.1 TL3, and later versions support the lsmpio command. For other AIX versions, you can only use the lspath command to query paths.