Scheduling an LDAS Database Backup
To facilitate nightly backups of the LDAS DB2 databases, we created a Perl script
backup_db2_SERVER_NAME.pl. This document explains how to configure the
script for any DB2 server and uses the MetaServer configuration as an example.
Step 1: Configure the databases for ONLINE backups
The ONLINE parameter of DB2's backup command tells DB2 to allow users to have full access to a database
while the backup is running. If the ONLINE parameter is not included in the command,
users are locked out until the backup completes.
To enable ONLINE backups, the LOGRETAIN and USEREXIT configuration settings must be set to RECOVERY and ON.
By default, both settings are set to NO to limit the amount of disk space needed for transaction logs.
You need to change these settings for all of the databases you want to backup with this script.
- Log in as the database instance user. For Metaserver, log in as ldasdb.
- Force all users out of all of the databases by issuing the following command:
db2 force application ALL
- Run the following command to configure the database to retain the transaction logs:
db2 update db cfg for [DATABASE NAME] using logretain recovery
- Run the following command to configure the database for user log management:
db2 update db cfg for [DATABASE NAME] using userexit on
- Backup up the database without ONLINE. After the backup, the server will begin
retaining the transaction logs and will be ready for ONLINE backups..
db2 backup database [DATABASE NAME] to /usr2/backup with 2 buffers buffer 1024
Step 2: Configure the Script for the Server
The script is designed to work on any DB2/Linux server. You just have to download it, change some
constants and environment variables at the top of the script and then run it. The original version
of the script has eight constants needed by the script and 5 environment variables
that are needed by DB2. The constants tell the script which databases to backup,
where to put the backup files, how long to keep old backup files, who to notify when the script
is finished, etc. Comments within the script provide information about each of the constants.
The script also explicitly sets several environment variables so that the DB2 commands will execute
properly under cron. Jobs running under cron have a limited set of environment variables.
- Click here to download the script. Save it into the home
directory of the DB2 instance owner
(or any other appropriate directory).
- Open the script in a text editor.
- Find the section of the script labelled CONFIGURATION CONSTANTS at the beginning of the script.
- Set each of the constants and environment variables for your environment.
- Save the script with the name of your server instead of SERVER_NAME. The script name contains the
server name to show that it has been configure for a particular server. For example, the MetaServer
script is named backup_db2_METASERVER.pl.
- Run the script to make sure that it is properly configured and
to backup the databases.
perl -w backup_db2_SERVER_NAME.pl
Step 3: Add the Script to Cron
To make the database backups routine, you need to schedule them. Cron is a job scheduling
software package that is standard on most flavors of UNIX. Scheduled jobs are listed in the
crontab files. Once a minute cron looks through the crontab files and runs
any jobs that are scheduled for that minute. This script is designed and tested to work with cron.
- Log in as the database instance user. For Metaserver, log in as LDASDB.
- To display the crontab file for the user in
a text editor, enter the following command:
- The crontab file is composed of comments lines and job lines. You should enter a comment
above each job to explain what it does. The job line is composed of 6 columns. The first 5 columns, which
specify when the job should run, stand for minute, hour, day, week, month. Enter these values as
numbers. If you want cron to run a job every minute, hour, day, week, or month, put an * instead of a number
in the respective column. You can enter multiple values for a column by seperating them with a comma.
For more information refer to the man pages for cron and crontab. Here's an example that schedules
the backup of Metaserver for everynight at 1:15 AM:
# min hour day week month job
# Schedule the LDAS DB Backup
15 1 * * * /usr2/ldasdb/backup_db2_METASERVER.pl
- Save your changes.
For more information, see the following:
- Performing a Database Backup, Restore, and Rollforward
- IBM DB2 Command Reference
- Quick Beginnings for DB2 Extended Enterprise Edition for UNIX
$Id: scheduling_ldas_DB_backup.html,v 1.20 2003/11/21 16:32:50 dsmackin Exp $