Question

Consistent backup


Userlevel 3

Hey guys, I have a question.

What kind of backup does veeam create, transactionally consistent or crash consistent backup? what is the difference between them? 


5 comments

Userlevel 7
Badge +4

Both are possible with Veeam.

Application aware backups are transactional consistent. You will use them for applications like databases or exchange to be sure that the application is recoverable to a consistent state with all transactions in a defined status.

The “normal” snapshot backups are crash consistent. You will use them for all other systems and applications where it does not matter that every single action is in a defined status.

Userlevel 7
Badge +6

You can do (I assume vSphere Backup jobs)

  • Crash consistent. This happens when do not enable VMware Tools Quiescence and Guest Processing.
  • Application Aware (incl. VSS). This happens when you enable Guest Processing. This is recommended by Veeam
  • “VSS Aware” and Disk Quiescence. When you just enable VMware Tools Quiescence.
  • Additional you can use freeze-only backups. These are Storage Snapshots-only backups without VMware Snapshots.
Userlevel 6
Badge +1

To simplify it even further

Crash Consistent = state of the machine at the time  when the VM was powered off e.g. Any data/transactions held in memory is/are lost

 

Transactional Consistent = Veeam instructs VM to commit data/transactions to disk, before taking the backup

 

?

Userlevel 4
Badge

https://www.veeam.com/blog/how-to-create-a-consistent-vm-backup.html 

This one is still relevant, even 7 years later..

Userlevel 7
Badge +5

I think everyone has covered it and that blog is still very relevant.

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