A large number of applications, and the operating system itself, depend on MDAC-contained components for proper operation.MDAC is not a single product; rather, it is a collection of DLLs and associated component resources to support a number of different APIs, including Open Database Connectivity (ODBC), OLE DB, Microsoft Active X Data Objects (ADO), and Microsoft Remote Data Service (RDS).There are a number of differences between SQL Server Native Client and Microsoft Data Access Components (MDAC; starting with Windows Vista, the data access components are now called Windows Data Access Components, or Windows DAC).Although both provide native data access to SQL Server databases, SQL Server Native Client has been specifically designed to expose the new features of SQL Server 2005, while at the same time maintaining backward compatibility with earlier versions.
A First, you may be interested to know that most post-installation reboots are not hardcoded into the installer. This means the installer is trying to update files that are currently in use (locked) by some other application or by the operating system.
There have been several deprecated components as well, such as the Microsoft Jet Database Engine, MSDASQL (the OLE DB provider for ODBC), and Remote Data Services (RDS).
Some components have also become obsolete, such as the former Data Access Objects API and Remote Data Objects.
Microsoft Data Access Components (MDAC; also known as Windows DAC) is a framework of interrelated Microsoft technologies that allows programmers a uniform and comprehensive way of developing applications that can access almost any data store.
Its components include: Active X Data Objects (ADO), OLE DB, and Open Database Connectivity (ODBC).