The usual strategies 100% cloud or 100% local data backup solutions do not allow for good risk control.
The “all” cloud is vulnerable to new cyber threats and/or major incidents (including among the major players).
The “all” local is subject to hardware risks and/or “traditional” attacks such as ransomware.
A mixed “hybrid” storage is by far the most secure strategy: local data storage and backup in the cloud.
If the cloud goes down, you temporarily lose collaboration but the local storage keeps all the data.
If the local one goes down, the cloud ensures the global continuity while waiting to recover the local one.
Cloud synchronization system between local and cloud has a security barrier:
When local computer is subject to an attack, synchronization is stopped.
After delate infected data or encrypted data user can restore on his computer within few minutes all cloud data.
The central platform and its contents are better protected because no direct sharing links are made.
Shared documents and transfers are isolated in independent containers separate from the central platform, avoiding risk of intrusion through sharing links.