Sybase 15.0.2 - Manual (Page 18)

Product components
4 Adaptive Server Enterprise
All server processes share two distinct areas of shared memory: a kernel area
and a DBMS area. The kernel area contains data structures that relate to task
management and operating system services, while the DBMS component
contains caches of database buffers, object descriptors, and other resources
used by the DBMS component of the server process.
The kernel layer of the server abstracts the operating system-specific functions
so that the rest of the server has a consistent view of those functions regardless
of the underlying operating system. Essentially, the kernel provides low-level
functions, such as task and engine management, network and disk I/O, and
low-level memory management to the rest of the server. The part of the server
that processes a TDS request (the TDS engine) is part of the kernel layer.
The heart of Adaptive Server is the SQL/DBMS engine. The SQL/DBMS
engine processes data manipulation statements (DML), utility commands,
which are generally data definition statements (DDL) and administrative
functions, and performs stored procedure executions. The DBMS engine uses
the services provided by the resource manager routines and the access methods
routines.
A resource manager is a set of subroutines that manage a particular system
resource, such as pages, buffers, or a particular data structure. The DBMS
engine uses these subroutines to manipulate various system resources. There
are also a number of tasks within the server that perform specialized tasks. The
resource managers, as well as these specialized tasks, rely on the kernel layer
for low-level functions.
Access methods have two primary functions: the management of data on disk
and manipulation of database constructs, such as tables and rows. Actual disk
I/O routines are provided to the access methods routines by the kernel disk I/O
routines.
Backup Server
Like Adaptive Server, Backup Server is also an operating system process.
Backup Server is dedicated to backing up and restoring Adaptive Server files.
Clients do not communicate directly with Backup Server. Only Adaptive
Server communicates with Backup Server.