Microsoft 365 Exchange Online - why only forever incremental backup?

  • 10 September 2021
  • 9 replies

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Hello everyone,


i’ve got a question to the backup from Microsoft 365 Exchange Online.

Why can we backup the mailboxes only as “forever incremental”?


Doesn’t it makes sense to be able to do a Synth Full from time to time?

I see why we can’t make a full backup over the internet. That makes totally sense to me.

The synthetic full however is performed directly on the Commserve and not over the internet.

Thats why i don’t understand that we are only able to do a forever incremental.


We already asked that our consultat, but he didn’t had an anwser either.

So maybe someone of you now the reasons for that.








Best answer by Chris Hollis 13 September 2021, 03:50

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9 replies

Userlevel 7
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Hi @Yoki 

Great question!

I’m discussing this internally with the teams and researching some internal resources so I can get you an answer on this one.



Userlevel 5
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Hope you’re well.

With the exchange mailbox solution, the entire architecture of archiving has changed - the agent now leverages V2 indexing - 

If you were to include a synthetic full option, many of the benefits this feature provides will become  redundant. 

The primary benefits for this approach is:

  • Less ‘footprint’ on your storage device(s)
  • Better scalability & reliability
  • Faster browse/search and restore capabilities

May I ask what would be the reason for needing a synthetic full in your environment for this type of data? 

If you were concerned about not having a ‘FULL’ to refer to, we do have the option to ‘Convert to FULL’ as per:

Note however the job type remains the same ‘incremental’, you’ll just see a spike in amount of date (size of application) as we’ll be backing up everything in the users mailboxes at that time.

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@Chris Hollis 

Thanks for your reply.

I asked because we usually only have our backups on our disks for a maximum of 6 weeks.

Older backups we have then only on tapes.

Now if we need to restore a mailbox whose backup is no longer on disk, I am concerned that we would have to request a lot of tapes then. 

With Synth Full backups, we would only need to request one tape.


Currently we have every incremental backup of Exchange Online on disk.

But this should not become a permanent state.



Userlevel 5
Badge +12

Hi @Yoki 

Thanks for clarifying.

We have a CMR (#​256668) currently being worked on to provide support for a ‘Full’ archive job for selective copies with this agent. This doesn’t necessarily mean it’s going to be a full backup job type, for example, it’s possible it may be a workflow that grabs or compiles incrementals that are on a tape / or that cover a certain time period and makes them one job, development are still designing this and there is no ETA on when it will be available. 

In the meantime, for your current situation, yes, if you’re hosting everything after 6 weeks on tape, overtime you’ll need more and more tapes to recover data, this is true.

You’ll most likely find that your tapes will however be able to hold a lot more jobs as they’ll be smaller increments of data… unless of course you have a large amount of mailboxes to protect (10s of thousands) and the rate of change between archive jobs is exponential. 

Smaller increments of jobs hopefully means less tapes required to cover a larger period of time. 

Is the current setup primary = disk, secondary = tape? or is there another disk copy you could take advantage of for mid-long term retention on disk? 

What kind of retention will you be applying to your tape copy? 




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@Chris Hollis is there any update on the CMR that you mentioned about a “Full” archive job for exchange online to use for selective copies? We’ve seen a rise in requests for such a possibility.

Userlevel 7
Badge +23

@ChrisK , nothing immediate, though someone beat me to it and updated the TRR stating that many of you are awaiting word on this request!

I just followed the actual CMR form, so as I see updates, I’ll come back here and update everyone (assuming it’s something I can share, of course)!

Userlevel 1
Badge +7

I'm looking forward too about full backups and get off the everyday incremental that runs for years... I prefer to proceed with a simple plan with  30 Inc daily backups and then GFS with synthetic monthly and yearly backups.

How many storage you are going to save from that?

Whats the reason to have every day incremental for 1,2 or 3+ years? 



is there an update for CMR (#​256668)?

Userlevel 7
Badge +23

@MarcusS , the new process was added to the documentation here: