It also expands the basic $2/month storage limit from 50GB to 100GB.

It is a new secured storage area in OneDrive, letting users store important or sensitive files.

Users can scan the documents in the Personal Vault directly in the OneDrive app.

And this is also very secure for your personal files.

Personal Vault puts no restriction on the number of files you save to it.

you’re able to store as many files you want, up to the total OneDrive storage limit.

Microsoft seems to be first one to add this feature.