The Hot Standby software dynamically and transparently switches
from writing to the original output file to the new file. There
is no need to stop or interrupt database replication operations
during the transition to the new output file.
The Replicate After_Journal Reopen_Output command performs the
following steps to reopen the output file:
1. Closes the current output file in which information about
replication operations is recorded.
2. Reopens the output file by opening a new file using the
original output file name. On OpenVMS systems, the Hot
Standby software opens a new output file using the originally
specified file name and a new version number. Thus, you can
view the original output file by specifying the older version
number. If disk space is a problem, relocate the old output
file to another disk.
You can enter the Replicate After_Journal Reopen_Output command
on either the master or standby node as follows:
Enter the
command . . . To reopen the output file for the . . .
On the master LCS server on the master database
database node
On the standby LRS server on the standby database
database node
You must explicitly enable the ability to write replication
startup information to an output file by including the Output
qualifier when you start replication operations (see the
Replicate_After_Journal_Commands Start command for more
information), or by specifying the BIND_ALS_OUTPUT_FILE, BIND_
HOT_OUTPUT_FILE, BIND_LCS_OUTPUT_FILE, or BIND_LRS_OUTPUT_FILE
logical name.
The Replicate After_Journal Reopen_Output command is useful when:
o The output file becomes too large
For example, as the output file grows over time, you might run
out of disk space or notice that the database performance is
slow. You can use the Replicate After_Journal Reopen_Output
command to free up space on the disk. Once the new output
file is open, you should relocate the old output file to a new
location or delete the file.
If the disk that contains the output file becomes full, the
Hot Standby software stops writing information to the file
(and on OpenVMS systems, a message is sent to the system
operator). Note that replication operations continue, even
when write I/O to the output file stops.
o You want to view the currently open output file
By using the Replicate After_Journal Reopen_Output command,
you can capture a snapshot of the output file and examine
replication operations without interrupting processing. You
can also view the contents of the current output file using
the Type command at the OpenVMS system prompt.
NOTE
You cannot use the Replicate After_Journal Reopen_Output
command to change the size or location of the output
file; the command is intended to create a new version of
an existing output file.
o You want to open an output file for a server process that is
actively performing replication operations
Defining a logical name is useful if you omitted the Output
qualifier when you entered the Replicate After_Journal Start
command to start replication. You can define a logical name
to specify an output file while replication operations are
active. This can be done by defining the appropriate logical
name, and then invoking the Replicate After_Journal Reopen_
Output command. This allows you to create an output file so
the server can start writing to the file. The advantage to
defining a logical name is that you do not need to stop and
restart the server.
Reference: See the Output qualifier discussion under the
Replicate_After_Journal_Commands Start Help topic.