IBM Data Server DB2 - Manual (Page 54)

40 DB2 Deployment Guide
A partitioned database is a database created across multiple database partitions.
Each database partition has its own processes, memory, and data storage.
These resources are not shared between partitions. Queries submitted to the
DB2 database are distributed to each database partition and processed in
parallel. If there are multiple processors in each database partition node, internal
parallelism can be used to achieve better performance. There could be more
than one database partition created on a machine. And this is transparent to the
user, who does not have to know what happens behind the scenes.
In this section, we discuss the considerations pertinent for a partitioned database
system.
Licensing for a partitioned database
The DB2 Data Partitioning Feature (DPF) requires a separate additional license
from that of the Enterprise Server Edition (ESE) license. In DB2 9.5, it is only
available through InfoSphere package (see
1.2.4, “Other DB2 products” on
page 8). The DPF license has to be applied to all the participating database
machines. The DB2 Data Partitioning feature can be activated using the
db2licm
command.
For licensing in detail, see 1.3.4, “License considerations” on page 20.
For a partitioned database system on Linux and UNIX, where more than one
machine participates, a shared directory has to be created on a file system and
used as the instance home
path . The DB2 instance is created in this shared
home directory, and the instance configuration files will be accessible by all
database partitions.
NFS
The Network File System (NFS) is a widely used protocol for remote file access,
and it is built based on a Remote Procedure Call (RPC). The NFS allows users
and applications to access files over the network as if the remote files are on the
local disks.
In a partitioned database environment, one computer is set up as the NFS
server. The instance home directory is created on this server and exported to
other participating machines, which are configured as the NFS clients. The file
systems exported on the NFS server are mounted by the NFS clients. The DB2
instance configuration files located on this directory could be accessed by every
partition.