Things to consider when moving a database

A main task of a DBA’s life is keeping database versions and hardware up-to-date. This sounds easy, but actually it is not. This is especially if the system was not touched for a long period of time. And there might also be a lot of applications using a database. This implies dependencies.
The todays story is about a server migration that we did a couple of weeks ago. It meant moving 7 databases to a new hardware which we did by simply stopping the databases on the old server, stopping ASM on the old server, mounting the ASM disks to the new server(s) and creating cluster resources for the databases. But there were several other things to take care of. The following list is long but might not be complete, so please feel free to comment on that to make the list as good as possible.

  • cron jobs of ALL users
    • copy cron entries and all references scripts/directories etc
  • scripts
    • copy any scripts that are on the old system
  • local applications
    • copy any application and their configuration that might run on the old system
  • tnsnames.ora of ALL clients
    • prepare TNS aliases for the new system and activate them during the migration
    • notify all application owners who do not use tnsnames.ora or directory services (JDBC Thin, EZ-Connect, …)
  • external procedures
    • be ea
  • directories
    • adump
    • diagnostic_dest
    • directory objects
  • database links in ALL other databases
  • backup
    • RMAN configuration, especially locations for backups and snapshot controlfile
  • connect identifiers in applications, that do not use tnsnames.ora (JDBC etc)
  • SSH keys, authorized_keys
    • prepare any remote systems that were able to login via SSH to work seamlessly with the new server
    • add any neccessary entries to known_hosts and/or authorized_keys on the new server
  • Monitoring systems
    • change your central monitoring tool to monitor the new environment

 

Once you moved everything to the new system it might be a good idea to keep the Oracle Listener(s) up and running on the old system for a while. Doing that, you will be able to monitor the listener logfiles and identify any application/user/interface that were not updated and  are still trying to connect to the old environment.