The Lenovo Storage V series products consolidate storage capacity for Lenovo and non-Lenovo application host systems using the iSCSI protocol. In this e-Learning module, you will learn about the role 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 Storage 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. In the IBM SAN Volume Controller product, each node is an individual server in a system, and two nodes 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 the iSCSI host-attachment methodology.
A storage area network, or SAN, uses switches, switch fabrics, and switch zones to connect host systems to storage devices. To provide redundancy, use two fully independent counterpart SANs. Use Ethernet connections to connect each host and the product to the local area network, or LAN. Multiple Ethernet connections between the LAN and the product also help ensure redundancy.
There are several steps to complete in configuring an Ethernet, or iSCSI, host. First, you need to configure the host and then configure the system. Next, you use the product management GUI to create the host object, select the I/O groups that the host can use, and map the volumes to the host. Finally, you work with the host system to discover the new disks. Let us look at each step in more detail.
To configure a host, first select a software- or hardware-based iSCSI initiator. This can be a software iSCSI initiator, such as Microsoft(R) Windows iSCSI Software Initiator, or it can be an iSCSI Host Bus Adapter, or HBA, inside a host server.
If you are using a software-based initiator, your next step is to verify the iSCSI driver installation. If you are using a hardware-based initiator, your next step is to install the HBA and iSCSI driver.
Finally, if applicable, install and configure the appropriate multipathing device driver for the host system. For details about how to perform these steps, see the host attachment topics in the information center.
Your next task is to configure the system by completing the iSCSI configuration. You perform this task once, as it applies to the entire system. Hosts address a node canister through a unique iSCSI qualified name, or IQN. IQNs are generated through the system. Each node has a unique IQN, and the system name and node name are used as the host IQN. So your first step in this process is to determine a naming scheme for your system and nodes that is not likely to change.
One important function of IQNs is related to high availability. Within a system, IQNs are generated for each node. You can assign iSCSI IP addresses to each node. If a node goes offline, the IQN and associated IP addresses will migrate to the other node in the I/O group, so that data flow to the hosts continues. This action is known as failover. When the node comes online again, the IQN and IP addresses are migrated back while the data flow to the hosts continues. This action is known as failback. Note that failback is not instantaneous and it might take several minutes to recover the path.
Next, open the management GUI and go to the Network panel. Select the Ethernet Ports option, then select a port from the list. Open the Actions menu and select Modify. Enter the IP address. Keep in mind that each node can have more than one Ethernet port and each port needs a unique IP address. Both IPv4 and IPv6 addresses are supported. Configure the ports that will have iSCSI connectivity, based on the volumes that the host will access.
Select iSCSI to modify iSCSI configuration properties such as system name, iSCSI Aliases and iSCSI name server. You can also select to modify the CHAP configuration from this panel. Authentication is discussed later in this e-Learning module.
For the next step, go to the Hosts panel. For each host you create, select Create Host. Select iSCSI as the host type.
Enter a name for the host and add one or more IP addresses for the available ports. Click Add Port to List for each IP address that you enter. Optionally, enable the Challenge Handshake Authentication Protocol, or CHAP, authentication. 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.
Now that you understand how to configure the host components, this is a good time to focus on authentication.
Recall that we mentioned the Challenge Handshake Authentication Protocol, or CHAP, during the creating hosts segment of this presentation. With CHAP, you can configure one-way or two-way authentication. With two-way authentication, you have a CHAP secret for the host and a different CHAP secret for the system. The host will need to know the CHAP secret of the system, and the system will need to know the CHAP secret of the host. With one-way authentication, only the system needs to know the CHAP secret of the host.
To enable two-way authentication, you first use the console to select CHAP authentication and set the CHAP secret used by the system. Keep in mind that this secret applies to the entire system. Next, create the host CHAP secret for each host. Then specify the system CHAP secret to the host. These two tasks are performed on the host system and instructions will vary depending on your host operating system. Last, use the host configuration panels to specify the CHAP secret of each host. For more information, see the host attachment topics in the information center.
If you are having problems attaching iSCSI hosts, here are some tips that might help. The problem might be related to the network. Test your connectivity between the host and ports. Try to ping the target IP on the system from the host. Ask the Ethernet network administrator to check the firewall and router settings. Check that the subnet mask and gateway are correct for your Ethernet network configuration. Check if the iSCSI client is able to discover the target IP address. See if you have configured a CHAP secret for the system and whether the authentication is failing. Look for failure messages in host-specific logs. Check if the iSCSI client is able to establish connection with the storage controller using the target IP. Look for any authentication failure messages in relevant logs if CHAP one-way or two-way authentication is set.
The problem might be related to your configuration. View the configured node port IP addresses by going to the Ports by Host panel and viewing the Status column of the port you are troubleshooting. If the iSCSI port is configured correctly and has a working Ethernet connection, it will be online. To ensure that the host mappings are correct, view the list of the volumes mapped to a host in the Host Mappings panel. You can also verify that the volume is online by viewing the Volumes panel.
The problem might also be related to the host. Verify that the host IQN is correctly configured. Use the operating system utilities (such as Windows Device Manager) to verify that the device driver is installed, loaded, and operating correctly.
In this e-Learning module, you learned about the role iSCSI hosts play within your environment, the steps to configure iSCSI hosts, troubleshooting tips, and additional resources you can use to find more detailed information.
To learn more, see the host attachment, configuration, and planning topics in the information center, or visit the Support website.