User's Manual

DATABASE BACKUP

It is possible to backup databases in 7signal Sapphire. Given a proper backup, the system

state may be recovered completely in case of system crash. There are two remarkably

different alternatives and an option not to backup the database. The default in 7signal

Sapphire is no backup. While this option is known to be non-optimal for any production

environment, it is chosen as default to force every organization to define their own backup

policy.

Backup options

Automated backup with server downtime

Backup with downtime is a circadian backup based on Unix cron that pauses the

measurements by stopping the Carat server and closing the underlying database

connections. In quiescent mode a full backup of the database is made and stored to the

desired location in the Carat server file system. The user is responsible for managing the

backup files, moving and purging and so on. This type of logging is later referred as offline

backup.

Automated backup without server downtime

Online backup is a circadian backup based on Unix cron that keeps 7signal Sapphire in

production while creating the backups. While this obviously is the most tempting option, it

comes with a price of heavier administration.

To understand the difference between the methods – thus making one able to decide on

appropriate backup policy – we must understand database logging methods first.

Database logging

In short, the logs of a database system are the most precious. It is justified to say that the

logs are the database as they are written first and the tables are updated after that.

IBM DB2 provides alternative logging methods that affect the backup options. So called

'circular logging

' method keeps the size of the logs very predictable. The other option used

in 7signal Sapphire is so called 'infinite archive logging

'. This is very flexible a logging method

provided that there is a special file system available. Practically the file system must not fill

up ever.

The default logging method in 7signal Sapphire is 'circular logging'.

Purging database logs

Circular logging

There is no need for purging in case of circular logging. The default logging method in 7signal

Sapphire is 'circular logging'.

Infinite archice logging

There is one secure way of purging the log files in the infinite archive directory. Offline

backup has to be done and this comes with price of the 7signal Sapphire halt. Offline backup