Oracle Zero Downtime Migration (ZDM) - Installation

甲骨文 Zero Downtime Migration is a widely used automated solution for migrating Oracle Databases into any Oracle-owned infrastructure, including Exadata Database Machine on-premises, Exadata Cloud@Customer, and Oracle Cloud Infrastructure (OCI), including Oracle Database@Azure.

Zero Downtime Migration provides a robust, flexible, and resumable migration process. Zero Downtime Migration integrates Oracle Maximum Availability Architecture (MAA) and supports Oracle Database 11g Release 2 (11.2.0.4) and later database releases.

Zero Downtime Migration Concepts

• Online migration methods incur zero or minimal downtime (typically less than 15 minutes) and can leverage either physical or logical migration methods.
• Offline migration methods will incur downtime on the source database as part of the migration process. It can leverage either physical or logical migration methods.
• Physical migration methods:Use Oracle Data Guard and RMAN to perform migrations.Allow you to convert a non-multitenant (non-CDB) source database to a multitenant (CDB) target database.
• Logical migration methods:Use Oracle Data Pump and, for online migrations, Oracle GoldenGate Microservices..Allow you to perform cross-platform migration where the source Oracle Database is running on Oracle Solaris or IBM AIX operating system, and the target is an Oracle Autonomous Database or Co-managed Oracle Database on Oracle Linux.

ZDM offers four different migration methods:

1. Logical Online Migration using GoldenGate
2. Logical Offline Migration using Data Pump
3. Physical Online Migration using Data Guard
4. Physical Offline Migration using RMAN

Lets begin with setting up Zero Downtime Migration Software -

Zero Downtime Migration (ZDM) software can be installed on a compute present at On-Premises or can be installed on a compute in OCI. Pre-reqs for ZDM server -

• Zero Downtime Migration software requires a standalone Linux host running on any one of the following platforms:Oracle Linux 7, Oracle Linux 8, or Red Hat Enterprise Linux 8.
• The Zero Downtime Migration service host must be able to connect to the source and the target database servers.
• Ensure that the Linux host has 100 GB of free storage space.

Lets assume we already have a Linux compute instance running Oracle Linux 8 (Oracle-Linux-8.9).

Install following OS packages -

glibc-devel, expect, unzip, libaio, oraclelinux-developer-release-el7, libnsl and ncurses-compat-libs

Login to the ZDM host as root user and create required user, group and directories -

[root@zdm-host]# groupadd zdm
[root@zdm-host]# useradd zdmuser -g zdm
[root@zdm-host]# mkdir -p /home/zdmuser/zdminstall
[root@zdm-host]# mkdir /home/zdmuser/zdmhome
[root@zdm-host]# mkdir /home/zdmuser/zdmbase
[root@zdm-host]# chown -R zdmuser:zdm /home/zdmuser/        

Download the ZDM Software from https://www.oracle.com/database/technologies/rac/zdm-downloads.html and copy it over to the ZDM Host under /home/zdmuser/zdminstall. Make sure to change the ownership to zdmuser.

Add following lines to /home/zdmuser/.bash_profile

ZDMBASE=/home/zdmuser/zdmbase; export ZDMBASE
ZDMHOME=/home/zdmuser/zdmhome; export ZDMHOME        

Login as zdmuser and unzip the software zip file under zdminstall.

Run the installation script -

./zdminstall.sh setup \
oraclehome=$ZDMHOME \
oraclebase=$ZDMBASE \
ziploc=/home/zdmuser/zdminstall/zdm21.4.1/zdm_home.zip        

Start ZDM services, verify the status of service and the version of ZDM -

$ZDMHOME/bin/zdmservice start
$ZDMHOME/bin/zdmservice status
$ZDMHOME/bin/zdmcli -build        

This marks the completion of ZDM installation and startup of ZDM services.

In the upcoming posts we'll discuss about different migration methods that ZDM offers.

Further Reading

ZDM Documentation - https://docs.oracle.com/en/database/oracle/zero-downtime-migration/21.4/zdmug/index.html#Oracle?-Database