Office 365 - Performance Considerations

The backup job uses Microsoft Office 365 API to read data from the cloud and store it in the Storage Vault. A large amount of data will be downloaded to the local device.

The backup job takes advantage of Office 365 server-side delta change APIs to efficiently perform incremental backup jobs.

• This applies to Mailbox (Email), Calendars, Contacts, OneDrive files, and Teams files, allowing for high-performance incremental backup.
  • Deleting any file from within a backup job snapshot will disassociate the backup job snapshot from the server-side delta change. If you delete a file from the most recent backup job snapshot, the next incremental backup job will require a longer duration.
• This does not apply to SharePoint lists, which may re-download data during each backup job, reducing performance.

The Office 365 API imposes some rate-limiting on the backup operation. This may limit the total performance of the backup job.

• One of the multiple imposed rate-limit rules is based on the target mailbox account. Each mailbox has its own rate limits. Magnus Box backs up multiple mailboxes in parallel; if the Office 365 tenant has a large number of mailboxes, the overall backup job performance would be balanced evenly across all the mailboxes. If the Office 365 tenant contains mailboxes with very different sizes, the single largest mailbox may reduce performance owing to the tail effect.