Configuring CES protocol service IP addresses

Protocol services are made available through Cluster Export Services (CES) protocol service IP addresses. These addresses are separate from the IP addresses that are used internally by the cluster.

Each CES protocol service IP address is assigned initially to one CES node, either explicitly as specified by the mmces address add command, or by the system. They can be moved later either manually or automatically in response to certain events. The sample command is shown:

mmces address add --ces-node Node1 --ces-ip 192.168.6.6

After you add the required CES protocol service IP addresses, you must verify the configuration:

mmces address list

Use mmces address add --ces-ip 192.168.6.6 to add an IP address to the CES IP address pool. The IP address is assigned to a CES node according to the CES address distribution policy.

CES addresses can be assigned to CES groups. A CES group is identified by a group name that consists of alphanumeric characters, which are case-sensitive. You can assign addresses to a group when they are defined by issuing the following command:

mmces address add --ces-ip 192.168.6.6 --ces-group group1

You can change the group assignment by issuing the following command:

mmces address change --ces-ip 192.168.6.6 --ces-group group2

You can remove the group assignment by issuing the following command:

mmces address change --ces-ip 192.168.6.6 --remove-group

A CES address that is associated with a group must be assigned only to a node that is also associated with the same group. A node can belong to multiple groups while an address cannot.

As an example, consider a configuration with three nodes. All three nodes can host addresses on subnet A, and two of the nodes can host addresses on subnet B. The nodes must have an existing non-CES IP address of the same subnet that is configured on the interfaces that are intended to be used for the CES IPs. Also, four addresses are defined, two on each subnet.

Node1: groups=subnetA,subnetB
 Node2: groups=subnetA,subnetB
 Node3: groups=subnetA
 Address1: subnetA
 Address2: subnetA
 Address3: subnetB
 Address4: subnetB

In this example, Address1 and Address2 can be assigned to any of the three nodes, but Address3 and Address4 can be assigned to only Node1 or Node2.

If an address is assigned to a group for which there are no healthy nodes, the address remains unassigned until a node in the same group becomes available.

Addresses without a group assignment can be assigned to any node. Therefore, it is necessary to use a group for each subnet when multiple subnets exist.

Note: IP addresses that are assigned attributes (such as object_database_node or object_singleton_node) do not follow the same policy rules that other IP addresses follow. If a node has an affinity policy set, the IP address that is associated with the assigned attribute fails back to its node.

Configuring IPv6 addresses in the CES interface mode

If you want to use IPv6 addresses, you must use the CES interface mode. To use IPv6 addresses in your cluster, after the upgrade to IBM Storage Scale 5.1.x is completed, do the following steps:

Define the NICs by using the mmces interface add command.
Before switching to the interface mode, check the NIC configuration by using the mmces interface check command.
Switch to the interface mode by using the mmces interface mode interface command.
Note: You can use the mmces interface check command at any time a problem is suspected to check the NIC configuration.
Add the IPv6 addresses in the Classless Inter-Domain Routing (CIDR) notation by using the mmces address add command.
Note: In the CES interface mode, you must add IP addresses only in the CIDR notation. For example:
```
IP:      1.2.3.4      or  123:124
CIDR:    1.2.3.4/14   or  123::124/88
```
For information about the CIDR notation, see Classless Inter-Domain Routing.

For more information, see mmces command.