HP XC System Software Installation Guide Version 4.0

• Console access (cpaccess)
F.3.7 Disk_io Role
Nodes with the disk_io role provide access to storage and file systems mounted locally on the
node. This role can be located on any node that provides local file system access to all nodes
using NFS. Assign this role to any node that is exporting SAN storage.
The configuration and management database for the NFS Server service supplied by this role is
nfs_server.
Nodes with this role normally reside in the utility cabinet of the cluster and have the most direct
access to storage.
You can assign other roles to a node with this role. However, you must be careful not to overload
the node so it can provide adequate NFS service.
F.3.8 External Role
The external role supplies the NAT server service, which does network address translation
within the cluster. This enables applications to access nodes that do not have an external network
connection. The configuration and management database name of the service supplied by this
role is nat.
Assign this role only to nodes on which you are configuring an external network connection.
If you installed remote graphics software, you must configure an external Ethernet device (the
external NICs) on the SVA nodes.
The system can have multiple nodes defined with the external role, supplying multiple NAT
servers to ease network traffic congestion.
To achieve improved availability of NAT, assign the external role to both nodes in the
availability set. If you assign the external role to another node in the system, it will be ignored.
Applications have no need to be aware of the actual internal IP address of a compute node
because a NAT server node handles all network requests.
F.3.9 Ldap_server Role
LDAP is a client-server protocol for accessing directory services. Nodes assigned with the
ldap_server role enable you to configure LDAP master and replication servers within the HP
XC system.
The configuration and management database name of the service supplied by this role is
ldap_server.
F.3.10 Login Role
Nodes with the login role accept login sessions of users. A user can submit jobs from the
command line on a node that is assigned with a login role. The jobs are distributed among
compute nodes to process the job. Nodes assigned with a login role must have a configured
external network connection.
The login role supplies a node with the LVS director service, which handles the placement of
user login sessions on login nodes when a user logs in to the cluster alias.
To achieve improved availability of the LVS director service, you must assign the login role to
three nodes. See the role assignment guidelines listed in Table 1-2 (page 31) for more information.
The configuration and management database name for the service supplied by this role is lvs.
F.3.11 Management Hub Role
A node with the management_hub role is an aggregation point for management activities.
The configuration and management database names of the services provided by this role are as
follows:
• Nagios monitor (nagios_monitor)
F.3 Role Definitions 219