Establish Affinity Between Systems

Special Features and Customization Tasks › Affinity Feature › Establish Affinity Between Systems

Establish Affinity Between Systems

You can establish affinity between multiple CA TPX systems on multiple hosts. Affinity on multiple hosts ensures that, when the host owning a set of terminals is down, the host acquiring ownership will interact with the end users in the same way as the original host.

To establish affinity between systems on multiple hosts

Specify a common alias name for each system included in the affinity group. You specify this name on the ACBNAME parameter of the APPL statement in SYS1.VTAMLST.
For example, if you are running system TPX01 on HOST1, and system TPX02 on HOST2, and you want to give them the common alias name TPXALL, the APPL statements would look like this:

TPX01 on HOST1:
```
TPX,PRIMARY
TPX01 APPL MODETAB=TPXLGMOD,LOGMODE=T3278M3,ACBNAME=TPXALL
```
TPX02 on HOST2:
```
TPX,PRIMARY
TPX02 APPL MODETAB=TPXLGMOD,LOGMODE=T3278M3,ACBNAME=TPXALL
```
Establish a controlling relationship between the affinity group and all or selected terminals by adding a LOGAPPL parameter to the terminal major node definitions in SYS1.VTAMLST.
The name you specify in the LOGAPPL parameter must match the alias name that you defined in the ACBNAME parameter in step 1. This causes VTAM to automatically log the terminal on to the CA TPX system in the VTAM domain that owns the terminal. (You can change ownership with the VTAM VARY NET,ACQUIRE command.)

In the example in step 1, the name of the affinity group to which the systems TPX01 and TPX02 belong is TPXALL, so the value in the LOGAPPL parameter must be TPXALL. A terminal major node definition for either system might look like this:
```
TERMABCD  LU  LOCADDR=5,         X
                 DLOGMOD=USERMDL2,  X
                 MODETAB=USERTABL,  X
                 USSTAB=USERUSS,    X
                 LOGAPPL=TPXALL,    X
               ISTATUS=ACTIVE
```
Note: ACF/VTAM's LOGAPPL processing can be inhibited if one of the following conditions occurs:
- CA TPX is not active
- The terminal is not active
- The owning application terminates its session