How much space is required for a full transform?

[Jongp3]

I'd like to know how much space is required for a transform job when using forward increamentals with sythentic fulls.

For example:

100Gb reverse incremental
4.5TB sythentic full
100Gb forward incremental
1.1TB forward incremental (added new VM)

My question is how much free space will be needed to preform the necessary tasks? I know the last time I did this it required alot of temporary space during the job and once it was finished I had a lot of free space left.

[Shestakov]

Hello Jonathan,
The amount of space equal to new Full backup should be required, in your case it about 5.5 TB. However, after the transformation, the size of older Full backup(4.5 TB) will be released.
Thanks!

[Jongp3]

So if I only have 3TB of free space the transform will fail correct?

[Shestakov]

Most likely yes. If you are short on repository space, but want to have same number of restore points, I suggest to use Forever incremental method. Thanks!

[Jongp3]

I'm not sure that is accurate, so you're saying anyone who is running Synthetic Fulls always needs to have Free space equal to the amount of used space?

So if I have 5TB of Backup data I always need 5TB free in order for the full/transform to complete? again doesn't sound right.


Wouldn't Veeam just "inject" the data into the current Full (vbk) thus only needing Free space equal to the amount of incremental data?

Isn't this what happens in a Forever Incremental method? The oldest incremental gets injected into the VBK and then the VIB associated with that data gets deleted.
For example a 5TB VBK file and a 1.1TB vib file the 1.1TB would be injected to make a 6.1TB VBK and the VIB would be deleted when completed. Thus I would only need 1.1TB of free space for this to be completed.

Really would like clarification on this.

Thank you

[Shestakov]

You don`t need to have twice more than is used, you just need enough space for an additional full backup. In your case it is 4.5TB of what you had in a previous full backup + 1TB of new added VM.

Wouldn't Veeam just "inject" the data into the current Full (vbk) thus only needing Free space equal to the amount of incremental data?

That happens in a case of forever incremental backup, since just 2 restore points are used in transform. In a case of Synthetic Full backup with rollback transformation, new .temp file is created and its size is around a size of full backup.
Thanks!