One of the most important documents that you'll need when managing your SAP Business One deployment is the Administrator's Guide.
It covers a lot of the key things you need to know when deploying the solution as well as system requirements and explanations of "under the hood" components of the solution.
The 9.3 Administrators Guide is no different and its packed full of good information - but remember, as 9.3 is in Early Adopter Program right now all the details are still subject to potential change
SQL Server:Administrator's Guide for SAP Business One 9.3 on MS SQL.pdf
HANA:Administrator's Guide for SAP Business One 9.3, version for SAP HANA.pdf