The Lenovo V Series family of products consolidates storage capacity for IBM and non-IBM application host systems using the Serial Attached SCSI, or SAS, protocol. In this e-Learning module, you will learn about the role SAS hosts play within your environment, the steps to configure hosts, troubleshooting tips, and additional resources you can use to find more detailed information.
In most Lenovo V Series products, each control enclosure contains disk drives and two node canisters, and the two nodes in the same enclosure form an I/O group. The I/O groups present volumes to host systems. These host systems connect to the volumes and read data from them or write to them, using the SCSI command set. This e-Learning module focuses on SAS host-attachment methodologies.
Direct SAS connections are supported. Connect a SAS port on the host to a SAS port on the node canister. To provide redundancy, each host should have one SAS port connected to each node canister in an I/O group.
There are several steps to complete when configuring a SAS host. First, you need to configure the host. Then, use the management GUI to create the host object, select the I/O groups, and map the volumes to the host. Finally, you work with the host system to discover new disks. Let us look at each step in more detail.
To configure a host, you need to first install the appropriate host bus adapter, or HBA, and the HBA driver on your host system. Then, install and configure the appropriate multipathing driver for the host system. For details about how to perform these steps, and to verify that the host operating system, HBA, and device drivers are all supported, see the Host Attachment topics in the information center.
Let us look at the importance of redundancy. Multiple connections should be established between the host and the system. Within these connections, a multipathing device driver can create multiple independent paths between the host and the nodes inside the system. If one of the paths fails for any reason, the multipathing device driver uses a different path to access the data. This action is known as failover.
When the original path comes back online, that path is automatically recovered and the multipathing driver can use it again. This action is known as failback. Note that failback is not instantaneous – it can take 30 minutes or more – so verify that all paths are online before performing a service action on the partner node.
For the next step, open the management GUI and go to the Hosts panel. For each host you create, select Create Host. Select SAS as the host type.
Enter a name for the host and add one SAS port for the available ports. You can either enter the SAS port manually or select it from a list. If the SAS ports for your host are not displayed in the list, ensure that the host has SAS drivers installed and is zoned correctly. If you find that the drivers are installed and that the hosts are zoned correctly, but you still do not see the SAS ports for your host in the list, enter the SAS ports manually. Click Add Port to List for each SAS port that you select. You can also edit the Advanced Settings information. Select Create Host to complete this task. After the host has been created, assign volumes to the host.
Finally, use the host system utilities to discover the new volume disks that will be made available by the product. You also have the option of creating a file system for those new disks. This task is performed on the host system. Instructions will vary depending on your host operating system, so consult your host system documentation for more information.
If you are having problems attaching SAS hosts, check the status of the SAS ports. Use the management GUI to go to the Monitoring > System Details panel. Here you can view the status of the SAS ports on the node canisters.
The problem might be related to your configuration settings. Check your WWPN configuration and your host mappings. To view your configured WWPNs, go to the Ports by Host panel, and view the Status column of the port you are troubleshooting. If the WWPN is configured correctly, it will be online. To view a list of volumes mapped to a host, go to the Host Mappings panel and ensure that the host mappings are correct. To verify that a volume is online, go to the Volumes panel.
The problem might also be related to the host. Use operating system utilities (such as Windows Device Manager) to verify that the HBA driver and multipathing device driver are installed, loaded, and operating correctly. Refer to the multipathing driver documentation for more information on how to perform this task.
In this e-Learning module, you learned the overall steps to configure hosts in this environment, including tasks that are performed using the management GUI. And, you viewed several items that you can verify when you are troubleshooting host-attachment problems.
To learn more, see the host-attachment, configuration, and planning topics in the information center, or visit the Support website.