Synthetic Full Backup in Veeam

https://www.experts-exchange.com/questions/28995537/Veeam-Synthetic-Full-Backup.html

I have posted the question in the above link.

Now I need to give a picture of the data in the storage.


Full, Incremental,Incremental, Incremental.

Today if I need to run Synthetic Full... if I understand it will create another Incremental from The production (Not from the storage),  then I believe  it will create another copy of an existing full backup from the storage, then it will merge the recent incremental to the copy of the full backup that we have created...

is this the process? or am I misunderstanding how Synthetic Full back works ?

Thank you
jskfanAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
That is correct, hence it allows you to reduce time being restore, because you would have to restore a Full+All Incrementals to get you up to date, rather than just restoring the full...

Most third party solutions now employ this mechanism of roll-up incremental into a full backup - hence what is called a Synthetic Full Backup, because it never really happened, it was as you say merged.

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David Johnson, CD, MVPOwnerCommented:
That is a forward incremental strategy there also is a reverse incremental strategy.  Reverse incrementals are best when you want to restore to the last backed up  date (pretty much always) and not back in time and uses the least space. the drawback of a reverse incremental is that for every changed byte you need 2 io's and not so great if the backup store is deduplicated. But you only have to restore the FULL if going back to the last backup time. https://www.linkedin.com/pulse/reversed-incremental-vs-backup-veeam-methods-impact-parham-ashoori
Veeam document on synthetic full backup https://helpcenter.veeam.com/docs/backup/vsphere/synthetic_full_hiw.html?ver=95
jskfanAuthor Commented:
I have talked to Veeam Engineer but was not convinced with his answer.
He stated that the new synthetic Full backup is always independent from the previous Full Backup, it is just created from the last incremental backups , in other words it is a sum of the last incremental backups.

It did not make sense to me as the Data in the initial Full Backup will not be included in the new synthetic full backup
====

The way it makes sense to me is  the initial Full Backup in the storage will be duplicated as a second copy then the last incremental backups will be merged to that second copy of full backup, this will form a new Full Backup..

any Comments on that ?

Thank you
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Yes, I believe that's how all synthetic backs are created in most software.
jskfanAuthor Commented:
it does not make sense to me.
if the initial Full was 2 years ago and after then it is only Incremental backups and Synthetic full backups on the week end.

then  if there is an issue then I will have to go back 2 years ago to restore initial full backup then restore  all the Synthetic full backups that came after ?
David Johnson, CD, MVPOwnerCommented:
no just the last synthetic backup and incrementals from that date.

A synthetic full backup does the merging for you without actually doing a full backup.Merges are expensive in the terms of disk iops so have the backup repository on another device that is independent of the production storage.
Gerald ConnollyCommented:
Lets start from the beginning:

Traditional method: Typically every week
Do a Full backup and then Incrementals daily, and to do a restore you need the Full + all the Incrementals since the Full
  or
Do a Full backup and then Differentials daily, and to do a restore you need the Full + the last Differential

Synthetic: (aka Incrementals forever)
Do a Fullback and then Incrementals daily - Then on a Regular basis (say weekly or even Daily) create a Synthetic Full by merging the last Full generated (apart from the first one this will always be the last synthetic Full), this is being done offline.
To do a restore you need the last Synthetic Full and all the subsequent Incrementals.

What you gain is not having to do Full Backups, and if you did a merge every day, faster Restores.
jskfanAuthor Commented:
let me put it this way

- Initial Full backup

Incremental1
Incremental2
Incremental3
Incremental4
Incremental5
Synthetic Full = Sum of Incrementals

So Synthetic Full is just like one Differential Backup , in other words it is missing data from Initial Full Backup
David Johnson, CD, MVPOwnerCommented:
no it is the same as if you did a full backup
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Maybe it would be easier on the understanding if you restored the backups....
jskfanAuthor Commented:
If I understand a bunch of Incremental backups together is just like you are doing a differential.
So not to be confusing I mean the last differential is equivalent to the Sum of the Incremental Backups (which is call Synthetic Full). Correct ?

if there is Disaster then you will still have to go back and restore the initial Full  backup (the one done from the production) and then restore all the Synthetics ...

** Probably the way to be safe and have faster and efficient restore is I will  need each month to do one Full backup from production . However this will raise another question which is  whether the previous Synthetic Full will be merged to this last Full backup done from Production ..?

Thank you
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Full Backups will increase your backup Windows (time) and increase your storage.

If you have not practiced restoring yet, I personally would recommend you try and do it, based on the design you have created to see if you are adequately covered.
David Johnson, CD, MVPOwnerCommented:
A full backup ignores incrementals/differentials it starts fresh. (it ignores the archive bit) and requires the most amount of storage and disk I/O as everything from the source must be copied to the destination.  In the theoretical best of worlds one would do a full backup always. Practical considerations (we have limits on our disk iops and network bandwidth) prompt us to do an incremental backup so we only tie up the network and users storage devices while we copy the changed files (the files with the archive bit set and then we turn the archive bit OFF)

Periodic synthetic full backups keep all of the disk iops/network traffic on the backup storage device and off the production machines. You get the benefits of a Full backup without tying up the resources of the production network and putting all of the demands on the backup devices.
jskfanAuthor Commented:
Let me put it this way.

Initial Full backup X has files : A,B,C,D,E,F

Incremental1 has file G
Incremental2 has file H
Incremental3 has file I
Incremental4 has file J
Incremental5 has file K

Assuming we run Synthetic Full backup Y on Saturday (No changes) , it will have files( G,H,I,J,K).
Well, this Synthetic full is not helpful as it is missing files A,B,C,D,E,F
 
we'll need at some point in time to merge that synthetic full with the initial full so that we'll have all the Data..
David Johnson, CD, MVPOwnerCommented:
A synthetic full backup also includes the original full backup (or it wouldn't be a synthetic full backup
Gerald ConnollyCommented:
@jskfan - a synthetic FULL backup is created by taking the last full backup and merging in all the subsequent incrementals - thereby creating a Full backup

So in your example Full backup X is merged with your incrementals1-5 to create a new full backup Y so it will contain all the files A-K
jskfanAuthor Commented:
Gerald Connolly

That was my initial thought about Synthetic Full Backup until Veeam Engineer who came with the Sale person, told me that the Sunthetic Full is independent from the Initial Full Backup

Gerald Connolly

Since you said it includes the initial full backup, how does this happen ?

example:

we have initial Full Backup X
then we took incremental each day

Inc
Inc
Inc
Inc
Inc

Then

Synthetic = ???

Does it duplicate the initial Full Backup X and merges to it Incremental Backups  (All from the Storage), and this called Synthetic Full ?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Does it duplicate the initial Full Backup X and merges to it Incremental Backups  (All from the Storage), and this called Synthetic Full ?

(Full Backup X + Inc1 + Inc2 + Inc3 + Inc4 + Inc5 = Synthetic Full)

yes
jskfanAuthor Commented:
Andrew:

let's say this week:
(Full Backup X + Inc1 + Inc2 + Inc3 + Inc4 + Inc5 = Synthetic Full) , will name it Full Backup Week1

is Next week going to be:
Full Backup Week1 +  Inc1 + Inc2 + Inc3 + Inc4 + Inc5 = Synthetic Full , will name it Full Backup Week 2
Inc1 + Inc2 + Inc3 + Inc4 + Inc5 = are the incremental of next week of course.

ans so on....
jskfanAuthor Commented:
Since we have veeam 9.5 , I guess the concept of Synthetic full backup has been changed. it is explained in this video:
https://www.youtube.com/watch?v=kyyHVnnXsYk
jskfanAuthor Commented:
But the first method "FORWARD" makes much more sense to me, as it does not purge older data.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
same as this with a better picture and relevant to 9.5, rather than v8 in the video!

https://helpcenter.veeam.com/docs/backup/vsphere/synthetic_full_hiw.html?ver=95

I would encourage to experiment, we have seen many failures in the IT industry, because IT Admins do not understand the practicalities of backup and restore, and blame it on the tools available, or Attend Veeam training, they now have several training courses available.
Gerald ConnollyCommented:
jskfan

(Full Backup X + Inc1 + Inc2 + Inc3 + Inc4 + Inc5 = Synthetic Full) , will name it Full Backup Week1

is Next week going to be:
Full Backup Week1 +  Inc1 + Inc2 + Inc3 + Inc4 + Inc5 = Synthetic Full , will name it Full Backup Week 2
Inc1 + Inc2 + Inc3 + Inc4 + Inc5 = are the incremental of next week of course.

Yes, thats the point of a Synthetic, and thats why its also know as "Incrementals forever" and yes except for the initial Synthetic the synthetics are independant of the original full backup!
jskfanAuthor Commented:
I checked our weekly full is around 60 Terabytes and Incremental around 15 terabytes

so Synthetic full includes the initial Full backup
jskfanAuthor Commented:
Thank you
Gerald ConnollyCommented:
@jskfan,

so Synthetic full includes the initial Full backup
the initial real Full backup (IFRB)  is a baseline. The first synthethetic Backup process, takes that baseline and applies all the incremental changes to it, so in your case about 75% of the IFRB will be in the first Synthetic, in the next Synthetic, all the incrementals since the first Synthetic will be applied changing say another 10% from the Baseline.
So without having to take the system down to do a Real Full backup, after two weeks, you have a Synthetic full backup that would be equivalent to the Real Full backup had you done one! and this goes on everytime you do a synthetic. As i said before this process is also know as "Incrementals Forever" although you may feel happier doing a Real Full backup periodically - say every 3 months or even 6 months
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