Adding a node to a system

You can add a node to the system by using the CLI or management GUI. A node can be added to the system if the node previously failed and is being replaced with a new node or if a repair action has caused the node to be unrecognizable by the system. When you add nodes, ensure that they are added in pairs to create a full I/O group. Adding a node to the system increases the capacity of the entire system.

You can use either the management GUI or the command-line interface to add a node to the system.

Before you add a node to a system, you must make sure that the switch zoning is configured such that the node that is being added is in the same zone as all other nodes in the system. If you are replacing a node and the switch is zoned by worldwide port name (WWPN) rather than by switch port, make sure that the switch is configured such that the node that is being added is in the same VSAN or zone.

Considerations when adding a node to a system

If you are adding a node that was used previously, either within a different I/O group within this system or within a different system, take into account that if you add a node without changing its worldwide node name (WWNN), hosts might detect the node and use it as if it were in its old location. This action might cause the hosts to access the wrong volumes.

You must ensure that the model type of the new node is supported by the software level that is installed on the system. If the model type is not supported by the software level, update the system to a software level that supports the model type of the new node.
Each node in an I/O group must be connected to a different uninterruptible power supply.
If you are adding a node back to the same I/O group after a service action required it to be deleted from the system, and if the physical node has not changed, then no special procedures are required to add it back to the system.
If you are replacing a node in a system either because of a node failure or an update, you must change the WWNN of the new node to match that of the original node before you connect the node to the Fibre Channel network and add the node to the system.
If you are adding a node to the SAN again, to avoid data corruption, ensure that you are adding the node to the same I/O group from which it was removed. You must use the information that was recorded when the node was originally added to the system. If you do not have access to this information, contact the support center for assistance with adding the node back into the system so there is no data corruption.
For each external storage system, the LUNs that are presented to the ports on the new node must be the same as the LUNs that are presented to the nodes that currently exist in the system. You must ensure that the LUNs are the same before you add the new node to the system.
If you are creating an I/O group in the system and are adding a new node, there are no special procedures because this node was never added to a system and the WWNN for the node did not exist.
If you are creating an I/O group in the system and are adding a new node that was added to a system before, the host system might still be configured to the node WWPNs and the node might still be zoned in the fabric. Because you cannot change the WWNN for the node, you must ensure that other components in your fabric are configured correctly. Verify that any host that was previously configured to use the node was correctly updated.
If the node that you are adding was previously replaced, either for a node repair or update, you might have used the WWNN of that node for the replacement node. Ensure that the WWNN of this node was updated so that you do not have two nodes with the same WWNN attached to your fabric. Also, ensure that the WWNN of the node that you are adding is not 00000. If it is 00000, contact your support representative.
The new node must be running a software level that supports encryption.
If you are adding the new node to a system with either a HyperSwap or stretched system topology, you must assign the node to a specific site.

Considerations when using multipathing device drivers

Applications on the host systems direct I/O operations to file systems or logical volumes that are mapped by the operating system to virtual paths (vpaths), which are pseudo disk objects that are supported by the multipathing device drivers. Multipathing device drivers maintain an association between a vpath and a volume. This association uses an identifier (UID) which is unique to the volume and is never reused. The UID allows multipathing device drivers to directly associate vpaths with volumes.
Multipathing device drivers operate within a protocol stack that contains disk and Fibre Channel device drivers that are used to communicate with the system by using the SCSI protocol over Fibre Channel as defined by the ANSI FCS standard. The addressing scheme that is provided by these SCSI and Fibre Channel device drivers uses a combination of a SCSI logical unit number (LUN) and the worldwide node name (WWNN) for the Fibre Channel node and ports.
If an error occurs, the error recovery procedures (ERPs) operate at various tiers in the protocol stack. Some of these ERPs cause I/O to be redriven by using the same WWNN and LUN numbers that were previously used.
Multipathing device drivers do not check the association of the volume with the vpath on every I/O operation that it performs.

After the new node is zoned and cabled correctly to the existing system, you can use either the addnode command or the Add Node wizard in the management GUI. To access the Add Node wizard, select Monitoring > System. On the image, click the new node to launch the wizard. Complete the wizard and verify the new node. If the new node is not displayed in the image, it indicates a potential cabling issue. Check the installation information to ensure that your node was cabled correctly.

To add a node to a system by using the command-line interface, complete these steps:

Enter this command to verify that the node is detected on the fabric:

svcinfo lsnodecandidate

This example shows the output for this command:

# svcinfo lsnodecandidate
id               panel_name UPS_serial_number UPS_unique_id    hardware serial_number product_mtm machine_signature
500507680C007B00 KD0N8AM                      500507680C007B00 S01      KD0N8AM       0001-S01    0123-4567-89AB-CDEF

The id parameter displays the WWNN for the node. If the node is not detected, verify cabling to the node.

Enter this command to determine the I/O group where the node should be added:
```
lsiogrp
```
Record the name or ID of the first I/O group that has a node count of zero (0). You will need the name or ID for the next step. Note: You only need to do this step for the first node that is added. The second node of the pair uses the same I/O group number.
Enter this command to add the node to the system:
```
addnode -wwnodename WWNN -iogrp iogrp_name -name new_name_arg -site site_name 
```
Where WWNN is the WWNN of the node, iogrp_name is the name of the I/O group that you want to add the node to and new_name_arg is the name that you want to assign to the node. If you do not specify a new node name, a default name is assigned; however, it is recommended that you specify a meaningful name. The site_name specifies the name of the site location of the new node. This parameter is only required if the topology is a HyperSwap or stretched system.
Note: Adding the node might take a considerable amount of time.
Record this information for future reference:
- Serial number.
- Worldwide node name.
- All of the worldwide port names.
- The name or ID of the I/O group