In s3 object storage, a file is broken up into as many as 10,000 parts. In SQL Server, the each part’s size is based on the parameter
MAXTRANSFERSIZEsince this is the size of the write operation performed into the backup file. The default used for backups to s3 compatible storage is 10MB. So 10,000 * 10MB means the largest file size for a single file is about 100GB. And for many databases, that’s just not big enough. So what can you do…first you can use compression. That will get more of your data into a single file.
This right here is the pain. Anthony shows a few ways to extend this number but there’s still a hard cap on maximum backup size, one we don’t have on-premises.