Analyze your Office 365 Backup requirements with ease


As organizations embrace the full suite of Office 365 and intend to extend their Veeam Availability Suite with Veeam Backup for Microsoft Officer 365, we often get the question on how to design the backup for Office 365 backup.

When you use Veeam Backup for Office 365, it creates a local or cloud backup of the information stored in Microsoft Exchange Online, Microsoft SharePoint Online and Microsoft OneDrive for Business. A typical question in the design phase is to calculate how much storage Veeam Backup for Office 365 requires.

Especially with the latest version of Veeam Backup for Office 365…
Veeam Backup for Office 365 version 4, released last month, offers object storage support, where backup data is stored in cloud storage like Microsoft Azure blob storage, Amazon S3 (or compatible) and IBM Cloud Object Storage. Especially for organizations wanting to use this feature it’s ideal to know the size of their storage needs. Although cloud storage may scale indefinitely, so would storage costs. Wrong calculations of required (future) storage would make these costs increase harder, especially when blob storage needs to be reconfigured and/or migrated.


Introducing the Office 365 Backup Sizing tool

Calculating how much storage Veeam Backup for Office 365 requires does not have to rely on guess work. Veeam’s Senior Solution Architect Hal Yaman created a web-based tool to provide you all the answers you need upfront, without a need to install anything: The Microsoft Office 365 Backup Sizing tool, version 2.


Version 2 of the Microsoft Office 365 Backup Sizing Tool offers the following functionality:

Overview of your Office 365 usage

Many organizations have no idea on the actual size of data in Office 365 services, like Exchange Online, SharePoint Online and OneDrive for Business.

From the navigation menu on the left of the Microsoft Office 365 Backup Sizing tool, you can see the actual storage use for Mailbox, OneDrive and SharePoint data and active users for each of the corresponding Office 365 services.

Trends in Office 365 usage

The Microsoft Office 365 Backup Sizing tool provides trends so you can provide accurate storage size projections for future growth, too. By default, the tool provides graphs for storage consumption for the last 7 days, but you can view storage consumption for as long as 180 days. You actually don’t have to calculate or export the data to get the trends, because the tool displays these trends in the lower left corner for Current State in terms of Change Rate for report Days in both MBs and percentage.

Calculation of data usage for Veeam Backup for Office 365

The last item in the left navigation menu reads Backup Sizing.

An example of the output of the Office 365 Backup Sizing tool

This is where to web-based tool shines! It provides a clear overview of:

  1. The number of mailboxes, drives and sites, along with their respective cumulative sizes in GBs.
  2. The sum of the Veeam Backup for Office 356 repository size.
    (depending on the checks you leave on for Mailbox Sizing, OneDrive Sizing and SharePoint Sizing, in case your organization wants to backup only selected services)
  3. The Backup infrastructure needed for Veeam Backup for Office 365 in terms of backup servers, backup proxies, repository servers and backup jobs.
  4. Several levers allow you to apply a storage multiplier, a change rate percentage, and percental increases in the number of mailbox users, archive users, OneDrive drives and SharePoint sites.

No dependency on a Global administrator account

For many organizations, it’s not a challenge to sign into the tool with an account with Global administrator privileges in Azure AD, but luckily, you don’t have to. This is good news for larger organizations where management is delegated to several groups. Assigning the Application administrator role in Azure AD and then consenting to the following permissions for the associated VboWebApp Enterprise Application suffices:

  • Microsoft Graph: Sign Users In
  • Microsoft Graph: View user’s basic profile
  • Microsoft Graph: Maintain access to data you have given it access to
  • Microsoft Graph: Sign in and read user profile
  • Microsoft Graph: Real all usage reports

Consent prompt for the Office 365 Backup Sizing tool



The Microsoft Office 365 Backup Sizing tool isn’t perfect.

Calculation of Archive Mailboxes

As the Microsoft Graph API currently does not offer a way to get information on archive mailboxes, this information is not available automatically in the Microsoft Office 365 Backup Sizing tool.

However, Hal Yaman provides a PowerShell script, that an admin can download. and run locally to retrieve the number of mailboxes with archive enabled, and read out the total size of all the archive mailboxes. Then, this information can be entered manually in the web-based tool.

Export of data

The Microsoft Office 365 Backup Sizing tool provides graphical representations of Office 365 usage, but all this goodness cannot be exported. The overall sizing recommendations for Veeam Backup for Office 365 can also not be exported.

I would welcome this functionality, to be able to include this data as an annex to Veeam Backup for Microsoft Office 365 design documents.

No clean exit

The way the Microsoft Office 365 Backup Sizing tool should be configured in a delegated environment is clearly documented. However, there are no instructions available for actions when you’re done with the tool.

My recommendation is to delete the VboWebApp Enterprise Application from Azure Active Directory when you have no further need for the Microsoft Office 365 Backup Sizing tool, using the following line of Windows PowerShell on a system with the AzureAD PowerShell Module installed:

Remove-AzureADServicePrincipal -ObjectId (Get-AzureADServicePrincipal -SearchString VboWebApp).ObjectId 



The Microsoft Office 365 Backup Sizing tool is a very helpful tool in the design process for Veeam Backup for Microsoft Office 365. I highly recommend it.

Further reading

Your Exchange Online Contingency Plan is here with Veeam Backup for Office 365  What’s New in Veeam Backup for Microsoft Office 365 version 4
Office 365 Backup Analysis
How to Delete App Registrations and Enterprise Applications from Azure AD

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