Consequences of syncing libraries beyond the limits?

Regular Contributor

According to https://docs.microsoft.com/en-us/office365/servicedescriptions/sharepoint-online-service-description... there is a limit of 5,000 items when syncing a SharePoint library using the OneDrive sync client. What isn't mentioned there is what happens when someone tries. We have a group whose Document library in their team site has over 42,000 items. Recently, one of the members of that group reported that files were being deleted by OneDrive. Sure enough, the Recycle bin in the site had thousands of entries, many duplicates of the same file apparently being deleted multiple times over the course of hours or days. I'm trying to piece together what happened (waiting for the admins to provide an audit log report). I didn't realize until after requesting that report that the library had so many files in it. 

 

So, does anyone know what actually happens when someone tries to sync a library with more than 5,000 items? I kind of assumed it would just stop and only sync the first 5,000, but don't know for sure. I'm using Power Automate to generate a really big library to test for myself, but if someone has already done that, I'd appreciate the feedback.

4 Replies
With the modern sync client (OneDrive.exe), you can sync up to 300K files in total across all libraries/sites. The general recommendation isn't to exceed 100K files in total for performance reasons, but you can absolutely synchronize >5K items in a single library.

You may want to investigate the unified audit log in the Compliance admin center to determine what happened with those files.
Yeah, I'm waiting for one of our admins to pull the audit log report for me. I only have SPO admin access to our tenant. I know why they centralized everything, but really wish it were still possible to access the data from the site collection admin interface.

@Chad_V_Kealey Did you ever figure this out? We experience similar behaviour with OneDrive Sync, either using Sharepoint Sync or Add Shortcut to Onedrive. Files seem to be deleted randomly, with hundreds of files in a short time. The number of files is more or less the same. I was wondering if you ever found the cause and maybe solution to this? T.i.a.

 

It was a lot of user error (user getting impatient waiting for sync to happen and dragging files/folders into or out of their OneDrive folder) and some file types that shouldn't be synced ("package" files on Mac OS, like Techsmith Camtasia project files, Endnote libraries, etc).