Reverse Incremental Question

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Reverse Incremental Question

Veeam Logoby Burgess » Fri Sep 15, 2017 10:00 am

Hi,

I had a quick question about forward incrementals, reverse incrementals, synthetic fulls and VBK files.

As I understand it Veeam will keep enough backup files (incremental or fulls) to fulfil the amount of retention points for a job. So, if I have a job that has 7 retention points and creates a synthetic full backup on a Friday I could potentially end up with 3 vbk files as i would need those to maintain the vibs that are part of the retention policy. I believe it would look something like the below

(f)----(m)--(t)---(w)---(th)--(f)----(m)--(t)---(w)--(th)--(f)
VBK - vib - vib - vib - vib - VBK - vib - vib - vib - vib - VBK

I'm currently in a situation where i don’t have the space to support another VBK file for the job. Could i get around having another VBK file by using roll backs? Would i still end up with multiple VBK files or would the roll backs be treated as good enough to support the retention points i need? In my head i'm seeing Veeam essentially taking the vibs and turning them into vbrs without having to create another VBK at all, but I’m not sure that’s how it actually works.

So, take the below. What would happen when the synthetic full runs on the Friday? Would it remove the Wednesday vbr at the end of the chain, then merge the m, t, w, th vibs in to the VBK and then create vbrs of them? Or would it create a new VBK file for the Friday resulting in two VBK files?

(w)--(th)--(f)-----(m)--(t)---(w)--(th)
vbr - vbr - VBK - vib - vib - vib - vib

Hopefully the above makes sense?

Cheers,

Steve.
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Re: Reverse Incremental Question

Veeam Logoby Burgess » Fri Sep 15, 2017 10:38 am

I think after some more googling i've actually answered my own question

https://helpcenter.veeam.com/docs/backu ... tml?ver=95

The transform option lets you reduce the amount of space required to store backups. Instead of two full backup files — a regular full backup and synthetic full backup — you will have only one synthetic full backup file on disk. Note, however, that the transform operation takes more time than simply creating a periodic synthetic full backup.


It would be good to just get that confirmed by someone in the know, though.

Cheers,

Steve.
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Re: Reverse Incremental Question

Veeam Logoby foggy » Mon Sep 18, 2017 2:08 pm

Hi Stephen, you're correct, Veeam B&R will create a new (synthetic) VBK file and then transform all previous files in the corresponding chain (up to the base VBK) into VRB's. After that retention will be applied removing the older VRB's, so finally you will come up with the VRB, VRB, VRB, ... VBK chain on disk.
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Re: Reverse Incremental Question

Veeam Logoby nmdange » Mon Sep 18, 2017 9:42 pm

You could also forego creating a synthetic full on a schedule and stick with forever-forward incrementals. If you are only keeping one synthetic full backup on disk, I don't see much reason to have it generate on a specific day of the week.

https://helpcenter.veeam.com/docs/backu ... tml?ver=95
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