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Hi team,

 

We all know about the type of general backups usch as incremental, full, synthetic full, differential etc

My colleague (a veritas user) wants to move forward with Veeam. However, he is not yet conviced, he is asking if veeam can:

  1. Perform general Differential backups efficiently and easily in VBR 12.1 with easy steps
  2. Perform Differential backups on VHDX/VHD, VMDK files with retention of choice

I welcome any detailed/explanation insight here. I would love to make him a new Veeam user/believer.

Hi @SysEng -

Well...Veeam doesn’t perform differentials (i.e. changes since last Full); Veeam performs incrementals after the Full (i.e. changes since last backup, beit a Full or last Incremental). As such, all backup files in an “active chain” (most recent Full and its subsequent Incrementals) need to be present on the Repository to perform a restore at a given point in time. 


Here is more info from the User Guide:

VM Restore - Backup Chain

https://helpcenter.veeam.com/docs/backup/vsphere/backup_files.html?ver=120#rolling-back-vms

Below shows how each method is done in Veeam (Forever Fwd Incremental, Fwd Incremental, & Reverse). 

https://helpcenter.veeam.com/docs/backup/vsphere/backup_methods.html?ver=120

I personally like the animated KBs Veeam has showing how each Backup Method works:

FFwd/Fwd: https://www.veeam.com/kb1932
Reverse: https://www.veeam.com/kb1933

Hope those help. Let me know if you have further questions.


So if SET A vhdx full backup was done on July 1 with size of 500 GB

Set A vhdx incr backup is set for Jul 4

However, SET A vhdx full backup changed to 550 GB on Jul 3

What will the new incremental size be for SET A?


Hi @SysEng - Sorry for the delay.

The incremental on the 4th would only be the size of the changes incurred since the Full was taken on the 1st. So the incremental would be roughly 50GB. And keep in mind, Incrementals are changes incurred since the last backup file was taken. So, if the last backup was an incremental and not a Full, the next Incremental would be the size of whatever changes were incurred since the last incremental.

For your Repositories, you can configure the storage to use ReFS (Win) or XFS (Lnx) and use Fast (Block) Cloning technology which, from a high level, essentially causes Veeam to only use pointers for needed backup data already on disk. So in theory, if in your 50GB of change data, you have some blocks already on disk identical to what’s needed for the change, you would have < 50GB for your incremental.

Hope that helps.


There is one restriction: The block cloning takes effect for synthetic fulls only, not for incrementals.

 

This does the trick with Veeam incremental backup chains. You can take a synthetic full - for example -  each week to keep your backup chains short. This makes them more manageable.

And with differential backups you would take a new full backup after a defined time, too.


“There is one restriction: The block cloning takes effect for synthetic fulls only, not for incrementals.” → Ah yes...that’s correct. Thanks for the assist there @JMeixner . Since I use it, you’d think I would’ve remembered 😂


I think my questions are too mind boggling, I am assuming here lol. I just like to reason out details best I can as an engineer, i mean 20 yrs in the business/IT career, designing, configuring, planning, deployment, testing etc, I just developed a habit of asking some intricate questions. Thanks for the clarity guys.


Nah...all good @SysEng 😊 Hope we helped you out.


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