Although the Start Journal Physical File (STRJRNPF) and End Journal
Physical File (ENDJRNPF) commands are distributed to other systems, the actual
journaling takes place on each system independently and to each system's own
journal receiver.
As an example, you have two systems (A and B) on which you have a distributed
file. You need to create a journal and a receiver on both system A and system
B, and the journal name and library must be the same on both systems. When
you issue the STRJRNPF command, the command is distributed to both systems
and journaling starts on both systems. However, the journal receiver on system
A contains only the data for changes that occur to the piece of the file that
resides on system A. The journal receiver on system B contains
only the data for changes that occur to the piece of the file that resides
on system B.
This affects your save and restore strategy as well as your backup strategy;
for example:
- After you issue the STRJRNPF command, you should save the database file
from each of the systems in the file's node group.
- You need to practice standard journal management on each of the systems.
You need to change and to save the journal receivers appropriately, so that
you can manage the disk space usage for each system. Or, you can take advantage
of the system change-journal management support.
Note: Just the names of
the journal must be the same on each of the systems; the attributes do not.
Therefore, for example, you can specify a different journal receiver threshold
value on the different systems, reflecting the available disk space on each
of those systems.
- If you do need to recover a piece of a distributed database file, you
only need to use the journal receiver from the system where the piece of the
distributed file resided. From that journal receiver, you apply the journaled
changes using the Apply Journaled Changes (APYJRNCHG) command or remove the
journaled changes using the Remove Journaled Changes (RMVJRNCHG) command.
- You are not be able to use the journal receiver from one system
to apply or remove the journaled changes to a piece of the file on another
system. This is because each piece of the file on each system has its own
unique journal identifier (JID).