Comparison of database backup methods

The method that you choose to back up your data determines whether IBM Spectrum Control remains online or offline during the backup process.

Advantages of an offline backup

The advantages of the offline backup method are:
  • The offline backup method is the default method and it is easier than the online method to configure and to maintain.
  • The circular type of logging that is used for offline backups is easier to configure and maintain than the type of logging that is used for online backups.

Disadvantages of an offline backup

The disadvantages of the offline backup method are:
  • You must stop IBM Spectrum Control when you back up the data. So data is not collected and your storage resources are not being monitored during the back up process.
  • You cannot collect performance data for the disk subsystems and SAN fabrics when data is being backed up.
  • You might miss critical events, for example, failures within a SAN fabric, that occur during the backup process.
Tip: To minimize the loss of data for your storage resources and to ensure that you do not miss critical events, back up your data when your storage resources are not being used or when storage usage is low.

Advantages of an online backup

The advantages of the online backup method are:
  • You continue to collect data and monitor your storage resources during the backup process because you do not have to stop IBM Spectrum Control.
  • You continue to receive alerts and can respond quickly to critical events at any time of day.
  • You continue to collect performance data for your disk subsystems and SAN fabrics.

Disadvantages of an online backup

The disadvantages of the online backup method are:
  • The archive type of logging that is used with this type of backup is a more advanced method; it requires a good knowledge DB2® operation and administration.
  • Software upgrades to IBM Spectrum Control that involve changes to the layout of the database might not complete successfully. In such cases, you can use circular logging to ensure that the software upgrade succeeds. You can switch back to archive logging after the software upgrade is installed.