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How to Startup Replicate from a Backup DDC File

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Problem Description

This article explains how to start the replicate processes using the backup DDC file

Solution

Every Dbvisit Replicate process started creates a backup ddc file in the ddc_backup directory, located in the "home" of your replication configuration. For example:

[oracle@dbvrep01 REPPOC]$ pwd
/home/oracle/REPPOC
[oracle@dbvrep01 REPPOC]$ ls -ltr ddc_backup/
total 32
-rw-rw-rw- 1 oracle oinstall 12379 Apr 29 15:44 REPPOC.MINE_20150429154447.ddc
-rw-rw-rw- 1 oracle oinstall 12493 May 1 21:52 REPPOC.MINE_20150501215252.ddc

The good thing is that you can pick a backup file from any machine in your configuration, as they are all equivalent. Of course, you should look to use the most recent file possible.

To start the "process" in question simply use:

--ddcfile ddc_backup/....(latest).ddc

So, for example, if I am attempting to start the MINE process in lieu of a missing/corrupt MINE ddc file then I could do the following:

  • Locate the most recent backup ddc file I have:
    [oracle@dbvrep01 REPPOC]$ ls -ltr ddc_backup/
    total 32
    -rw-rw-rw- 1 oracle oinstall 12379 Apr 29 15:44 REPPOC.MINE_20150429154447.ddc
    -rw-rw-rw- 1 oracle oinstall 12493 May 1 21:52 REPPOC.MINE_20150501215252.ddc
  • Adjust the MINE start process command to invoke this backup file:
    /usr/bin/dbvrep --daemon --ddcfile
    /home/oracle/REPPOC/ddc_backup/REPPOC.MINE_20150501215252.ddc start MINE
  • Execute this to start the MINE process:
    [oracle@dbvrep01 REPPOC]$ /usr/bin/dbvrep --daemon --ddcfile /home/oracle/REPPOC/ddc_backup/REPPOC.MINE_20150501215252.ddc start MINE
    Initializing......done
    Dbvisit Replicate version 2.7.12.4968
    Copyright (C) Dbvisit Software Limited. All rights reserved.
    DDC file /home/oracle/REPPOC/ddc_backup/REPPOC.MINE_20150501215252.ddc loaded.
    Starting process MINE...started

It is also possible to use a backup ddc file for MINE from the target (APPLY) server - and vice versa.

So here I locate the most recent ddc backup on the target server and scp this to the ddc_backup directory on the source:

[oracle@dbvrep02 ddc_backup]$ ls -ltr
total 48
-rw-rw-rw- 1 oracle oinstall 12403 Apr 29 15:45 REPPOC.APPLY_20150429154502.ddc
-rw-rw-rw- 1 oracle oinstall 12493 May 1 21:53 REPPOC.APPLY_20150501215258.ddc
-rw-rw-rw- 1 oracle oinstall 12493 May 1 21:59 REPPOC.APPLY_20150501215905.ddc
[oracle@dbvrep02 ddc_backup]$ scp REPPOC.APPLY_20150501215905.ddc oracle@dbvrep01:/home/oracle/REPPOC/ddc_backup
Warning: Permanently added 'dbvrep01,10.158.97.207' (RSA) to the list of known hosts.
REPPOC.APPLY_20150501215905.ddc 100% 12KB 12.2KB/s 00:00

Adjust the MINE start process command to invoke this backup file. Note: The APPLY name does not matter as the backup files contain the settings for all processes:

/usr/bin/dbvrep --daemon --ddcfile
/home/oracle/REPPOC/ddc_backup/REPPOC.APPLY_20150501215905.ddc start MINE

Then execute the following to start the MINE process:

[oracle@dbvrep01 REPPOC]$ /usr/bin/dbvrep --daemon --ddcfile /home/oracle/REPPOC/ddc_backup/REPPOC.APPLY_20150501215905.ddc start MINE
Initializing......done
Dbvisit Replicate version 2.7.12.4968
Copyright (C) Dbvisit Software Limited. All rights reserved.
DDC file /home/oracle/REPPOC/ddc_backup/REPPOC.APPLY_20150501215905.ddc loaded.
Starting process MINE...started
...
/ Dbvisit Replicate 2.7.12.4968(MAX edition) - Evaluation License expires in 58 days MINE IS running. Currently at plog 78 and SCN 1670524 (05/01/2015 22:07:31). APPLY IS running. Currently at plog 78 and SCN 1670510 (05/01/2015 22:07:29). Progress of replication REPPOC:MINE->APPLY: total/this execution

Note

This is good only if it is only the DDC database which is not available. MINE will of course still need source to be available in order to run; APPLY needs both source and target.

This is good if you have a ddc on A and you want B=>C to be up and running.

And of course, if you set a new value of a variable, it does not update the ddc file on disk (similar to attempting to update an SPFILE when a DB is started from init.ora).

Mike Donovan May 01, 2015 23:28

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