HADR Database Writer

How To Find Database Writer?

  1. Goto Zoom database redo directory location.
    • Redo directory location can be found in file <zoom_installation_dir>/conf/server.xml inside the dbspec tag.<dbspec>
      <redoLogDir>/Volumes/NAS/ZOOM_HADR/ACME-SERVER/db/redo</redoLogDir>  <--- Redo directory location
  2. Open file "dlg-data.lck"
  3. Peer name mentioned in this file is the database writer.
"dlg-data.lck" file is created when Zoom server first starts up.  The Zoom server which starts up first will become the database writer and all other Zoom server will become read only peers. 
Now throughout the life time that server will be the database writer( aka. db writer)

Change Database Writer

Please strictly follow the below mentioned steps in same order else it might result in database corruption:

  1. Stop the existing database writer server.
  2. Open and edit “dlg-data.lck” file.
  3. Remove the existing database writer name from “dlg-data.lck” file. And write the name of new database writer. Just add the Zoom server name (peer name ) in the first line of this file in the same case as mentioned in hadr spec of server.xml. File should contain only the database writer name in the first line and nothing else.
  4. Save the file.
  5. Start the Old database writer server.
  6. Restart the new database writer server.
  7. Check the Zoom server logs of old database writer and new database  writer to verify the changes.
  8. On read only servers which are not database writer you will find a line in server logs on Zoom server startup something like:
    Server “XYZ-2” is in DB read-only mode. The DB writer server “XYZ-1” last started in write mode on “Sep 3 2015 02:33:15 PM”.
    If above mentioned line is present in server log when it starts that means the servers is in Read only mode. “XYZ-2” is the name of the current server and XYZ-1 is the name of existing database writer server.
    XYZ-1 and XYZ2 are just sample names.

If “dlg-data.lck” is deleted and afterwards any Zoom server restarts and found it missing, will become the database writer.

It is strictly recommended to not deleted this file once it is generated while all Zoom servers are running.

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