
Chapter 2
87
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
servers—either when they are started, or when the master copy is
changed—so that all backup servers hold a copy of the latest
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 CPI-C conversations using symbolic destination names defined
in the configuration file.
NOTE
If the LAN is split by a network failure into two noncommunicating
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 re-established, the domain configuration file from the
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
Summary of Contents for HP-UX SNAplus2
Page 4: ...4 ...
Page 14: ...14 Contents ...
Page 22: ...22 ...
Page 23: ...23 1 SNA Terms and Concepts ...
Page 65: ...65 2 Introduction to SNAplus2 ...
Page 107: ...107 3 Administering SNAplus2 ...
Page 132: ...132 Chapter3 Administering SNAplus2 Using the Command Line Administration Program ...
Page 133: ...133 4 Basic Configuration Tasks ...
Page 142: ...142 Chapter4 Basic Configuration Tasks Configuring Logging ...
Page 143: ...143 5 Defining Connectivity Components ...
Page 167: ...167 6 Configuring Dependent LUs ...
Page 174: ...174 Chapter6 Configuring Dependent LUs Defining LU Pools ...
Page 175: ...175 7 Configuring APPC Communication ...
Page 208: ...208 Chapter7 Configuring APPC Communication Configuring APPC Security ...
Page 209: ...209 8 Configuring User Applications ...
Page 222: ...222 Chapter8 Configuring User Applications Configuring RJE Workstations ...
Page 223: ...223 9 Configuring Passthrough Services ...
Page 235: ...235 10 Managing SNAplus2 from NetView ...
Page 248: ...248 Chapter10 Managing SNAplus2 from NetView Using UCF ...
Page 249: ...249 11 Managing SNAplus2 Clients ...
Page 300: ...300 Chapter11 Managing SNAplus2 Clients Managing HP UX Clients ...
Page 301: ...301 A Configuration Planning Worksheets ...
Page 337: ...337 B APPN Network Management Using the Simple Network Management Protocol ...
Page 343: ...343 C Configuring an Invokable TP Using snaptpinstall ...
Page 353: ...353 D Using SNAplus2 in a High Availability Environment ...