It doesn’t matter what type of organization you are; small, big, public or private – everyone has a database of some description. Databases come in many forms from Microsoft Exchange, Oracle, SQL to a litany of lesser known databases. The database, for many companies, is the ‘crown jewel’ of their data. More often than not, it contains critical customer, financial or business transaction data. So if we can all agree that it’s mission critical, by extension we can also agree that it needs to be backed up and protected properly.
There are few different approaches that can be taken to back up a database. I’ll review the pros and cons of each approach and also explain what I believe best of breed looks like.
Flat File backup
This is most basic of backups. All you are doing is backing up the database or its folders in flight possibly while transactions are occurring. Its fast and simple but the issue centers around the restore. If the database and log files are not properly quiesced then it becomes much more problematic to do a restore because the database and log files were not in sync at the point of backup. You can use this method if you shut down the database nightly but for many organizations, their databases run 24X7.
Crash Consistent backup
When running databases in a virtual environment, you can perform a VSS backup which is a Microsoft API that allows backup vendors to create a ‘snapshot’ of a VM for the backup application. Although the VM is quiesced, not all databases support this method of backup. There are also number of other things that in general, you should be aware of when using VSS. Its fast and a generally reliable method of backup in general but there are a few caveats to keep in mind.
Application Consistent backup
This is, generally speaking, the best method of backup up a database. An application consistent backup usually requires the use of an agent that resides on the physical server or VM being backed up. The benefit of this method is that the agent is written and designed for use with the specific database you are backing up. This has the added benefit of leveraging features that you simply won’t get with a VSS backup. If you look at the snapshot of Netvault’s Oracle agent options, it’s a clear example of that. Some vendors will tell you that agentless is better - I disagree. For the amount of space and resources a small agent consumes, I believe the benefit substantially outweighs any perceived downside.