Considerations before restoring large SharePoint Online sites:
1. Restoring large SharePoint Online sites might take significant time (up to several hours). This behavior is expected and is caused by the number of files to restore and throttling on Microsoft side.
1a. The number of files is a crucial factor to consider and is much more important than data size, because the archive is a file archive so each file has to be extracted from the archive and then created on Microsoft 365 side. Restoring single 6GB file would take much less time than restoring 10000 files that sum up into 6GB.
When recovering sites with 10k+ files, consider splitting files into several recovery tasks and select up to 5000-6000 files for each task.
1b. Running multiple cloud-to-cloud recovery jobs simultaneously is not recommended as in fact they would be performed by the same cloud Agent and use same IP address for outgoing connection so it would be throttled by Microsoft same way and total Agent performance for files extraction and upload would be about the same (or slightly higher). Our development team is working on redesigning product behavior to avoid MS throttling.
2. SharePoint versioning is turned off during restore.
Restore with overwriting creates additional versions of files with original size. As a result, each file occupies 2 times more space due to Microsoft 365 versioning design. Upon customer feedback, added changes in our product to disable versioning during restore (feature was implemented with Acronis Data Cloud 7.9 release). Also restoring files with both Acronis and native versioning could cause conflicts if a user would try to restore same data at the same time simultaneously.
3. Percents of recovery task progress do not represent to the actual amount of data already restored.
They indicate recovery task stage. 1-3% is preparation for restore, requirements check, etc., At 4%, data recovery begins. Although recovery might be running well, the percentage might not get updated for a long time and then quickly jump to a large number.
If a recovery task fails by timeout, it would restart and files that were restored during the 'failed' activity are already available in Microsoft 365.