I need to store 1TB of data in a single SharePoint Document Library in SharePOint Online. IS it possible? Does SharePoint online libraries have any limit in size? What could be repercussion of it. Please highlight?
According to this article, 1 TB is the maximum storage size of a site collection in SharePoint Online. So, accordingly you won't be able to upload 1 TB of data in one document library.
IMHO, uploading that much data into single library will also be a design issue depending upon your use-case.
The default maximum file size is 250 MB. This is a configurable limit that can be increased up to 2 GB (2,047 MB). However, a large volume of very large files can affect farm performance.