Introduction to SNAplus2
SNAplus2 Components
| In a domain with multiple SNAplus2 servers, one server holds the |
| master copy of the SNAplus2 domain configuration file. This server is |
| known as the master server. You can define other servers on the LAN to |
| be backup servers. The domain configuration file is copied to backup |
| |
| |
| information. |
| In general, you should define at least one backup server in addition to |
| the master server. Any remaining servers can be defined as additional |
| backup servers, or they can be left as peer servers. A peer server obtains |
| domain configuration information from the master server as required, |
| but cannot act as a backup server. |
| If the master server fails, the first backup server on the list of servers |
| defined for the domain takes over as the master. The domain |
| configuration file on this server is used as the master copy, and is copied |
| to other servers as necessary. When the master server is restarted, it |
| receives a copy of the domain configuration from the backup server |
| currently acting as master, and then takes over as the master. |
| If at any time the master server and all backup servers are inactive, a |
| node on a peer server can still operate, and you can still change the |
| node's configuration. However, you cannot access the domain |
| configuration file, and therefore cannot access the configuration of |
| domain resources (as opposed to node resources). This means that you |
| cannot start the 3270 emulation program, start the RJE programs, or |
| allocate |
| in the configuration file. |
| If the LAN is split by a network failure into two noncommunicating |
NOTE | |
| domains, each containing one or more backup servers, SNAplus2 cannot |
| maintain a consistent configuration of domain resources across the LAN. |
| In this situation, each domain has an acting master server, each tracking |
| changes made to the domain configuration file in its own domain but |
| unaware of any changes made in the other domain. When the LAN |
| connection is |
| original master server becomes the domain configuration file across the |
| LAN, and any domain resource files on other servers are overwritten. (If |
| the master is inactive at this point, the domain configuration file from |
| the highest backup server available in either of the two domains is used.) |
| Because changes to a domain configuration file are not necessarily |
Chapter 2 | 87 |