checkpoints run, the database writers would join into the process to write
the changed database blocks back to the datafiles.
Understanding how Oracle handles transactions will help you in sizing
the memory, undo tablespaces, and redo logs. Being able to have consistent
reads in the database and provide a way to access the data without being
blocked or needing to wait for transactions to complete is also key in the
performance of queries against the database.
Summary
SQL Server has system databases, such as master, msdb, model, and
tempdb. Even though Oracle does not have individual system databases
that match the ones in SQL Server, the platforms share some similar
concepts. There is a need for system information, there are parameters and
options that can be configured and viewed, and transaction logging keeps
track of changes.
Oracle has memory structures for supplying memory to server processes
and user processes. There are individual parameters to manually configure
memory, or dynamic settings that are available in Oracle Database 11
g
by
setting one parameter. Data dictionary views show the system information,
including the values of the parameters. Oracle offers quite a few parameters
for tuning and adjusting to provide the best performance options. We went
over only a small portion of them in this chapter, but you have a starting
point for common requirements.
Temporary and undo tablespaces are distinctive features of Oracle. It is
able to have more than one temporary area that can be assigned to different
users to isolate their sorting and temporary table processing. The undo
tablespace keeps track of the before and after copies to provide consistent
reads for concurrent users and be able to roll back changes if needed.
Changes are written to redo logs and kept in the undo segments to
handle transactions. There is also a memory cache for the logs to buffer the

version of the operating system to use.
Just as with SQL Server, you’ll need to decide where to install the
software, where to create the databases, and whether to use the default
installation (probably for a test environment) or a custom installation (for
a production environment).
This chapter covers Oracle installation, beginning with the operating
system preparations. Along the way, we will look at some scripts that you
can use to make the rollout to other environments a repeatable process.
Operating Systems
The installation of the Oracle software is very similar on the different
operating systems. Some of the types of checks are also the same, such as
making sure the version of the operating system is compatible with the
version of the database. A 64-bit Linux version of Oracle will not install
on a 32-bit Linux or Windows 64-bit system, for example.
The Oracle release notes provide information about where to find the
compatibility matrix and the system requirements for the server. As shown
in Table 3-1, the requirements listed are minimum values; they might not be
adequate for some systems to perform as needed. The additional Oracle
components may have some requirements outside the database lists. So, the
44
Oracle Database Administration for Microsoft SQL Server DBAs
components you plan to install will also determine what is needed for the
server. The disk space requirements depend on the components installed,
but the base product alone does require more disk space for 64-bit operating
systems. Also note that newer processors that are not listed could meet or
exceed the minimum requirements.
You can use the following command-line option to run the installer with
parameters to perform just the system prerequisites checks, without continuing
to install Oracle:
E:\Oracle11gR2\database> setup.exe -executeSysPrereqs

*For Linux, the swap space should be the same as the RAM up to 16GB.
TABLE 3-1.
Hardware Requirements (Minimum Values)
Since SQL Server DBAs are familiar with the Windows platform, we will
first discuss the Windows setup for Oracle. Then we will cover Linux, which
is a popular platform on which to run Oracle databases. For those who are
considering the move from a Windows-based to a Linux-based database
system, I will review some useful Linux commands and point out where to
find the information to validate the configuration and prerequisites.
Windows Setup
There are advantages to installing Oracle on the Windows platform. One is
that as a SQL Server administrator, you are already working with a Windows
system. Another is that some tasks that must be done manually on the Linux
platform are taken care of automatically on Windows. For example, the
environment variables are set up for you, and Windows handles the startup
and shutdown of services.
Oracle Homes
SQL Server tends to have a default location for the binaries, and Oracle will
set up a default as well: the Oracle home directory. This directory location
can be set during the installation process, or it can be specified by setting
the ORACLE_HOME environment variable before running the installer.
Although the environment variables are set by the Oracle installer for
Windows, there might be more than one Oracle home on a server. If this is
the case, when using a command line, you will need to set the variable
ORACLE_HOME first, or fully qualify the path to the correct Oracle home.
C:\> set ORACLE_HOME=d:\oracle\product\11.2.0\db_1
C:\> set ORACLE_SID=orcl
C:\> sqlplus
The release might be different for the Oracle homes, so looking at the
set environment variables will be one way of noticing what homes are

If you are using a dynamic configuration (DHCP), a test conducted during
the Oracle installer’s prerequisite check will fail if Microsoft Loopback Adapter
is not the primary network adapter on the system. Here is a quick check for this
adapter:
C:\> ipconfig /all
Ethernet adapter Local Area Connection 2:
Connection-specific DBS Suffix :
Description :Microsoft Loopback Adapter
Physical Address :7A-80-4C-9F-57-5D
DHCP Enabled :Yes
Autoconfiguration Enabled :Yes
If Microsoft Loopback Adapter is not configured, you can set it up
through Add/Remove Hardware in the Control Panel. Select Network
Adapters, and add it as a new network adapter.
Chapter 3: Oracle Installation
47
Useful Linux/Unix Commands
Linux might be a new operating system for you. If so, you will be happy to
learn that there are graphical user interface (GUI) tools as well as simple
commands that will help you navigate through the Linux environment.
Here, I’ll introduce some commonly used Linux commands. If you’re
already familiar with Linux, you can skip to the next section, which covers
Linux setup for Oracle installation.
Table 3-2 compares some of the command-line commands for Windows
and Linux. As you can see, several are the same or similar.
CAUTION
When you are dealing with files from the
command line, you should be aware that files
removed with
rm

■
chgrp Changes the group for permissions of a file or directory.
■
chown Changes the owner of a file or directory.
The manual pages (man pages) provide parameter options and examples
of how to use the commands. To access the man page for a command, just
type man and the command at the prompt, as in this example:
> man grep
When you download files for a Linux system, such as patches or
software, they might come in a couple of formats, with file names ending in
.Z, .gz, .zip, .cpio, or .tar. These are compressed files. You’ll need to
Chapter 3: Oracle Installation
49
Task Windows Linux
List files and directories Dir ls
Change directory Cd cd
Copy file Copy cp
Move the file to another name or location Move mv
Delete a file Del rm
View contents of a file Type cat or more
Make a directory Mkdir mkdir
Remove a directory Del rm –r
View the current environment variables Set env
TABLE 3-2.
Command-Line Commands in Windows and Linux
uncompress these files so that they are usable. The following are sample
commands to uncompress the various formats:
> uncompress *.Z
> unzip *.zip
> gunzip *.gz

Figure 3-1 shows these users listed in User Manager, which is a Linux
tool for managing user permissions and group associations.
As you can see in User Manager, for each user, there is also an
associated /home directory. You can browse through the directories and
look at the file systems using the GUI, by clicking the Computer or Oracle’s
Home icon on the desktop (also shown in Figure 3-1).
The oracle user is not normally created in Linux with full
administration permissions, but certain rights are needed for resources for
the software to run properly. The /etc/security/limits.conf file has the
resources for nproc and nofile, which allow a certain number of
processes and number of files to be open by the user, and possibly memory
limits. Session permissions are in the /etc/pam.d/login file. View these files
Chapter 3: Oracle Installation
51
FIGURE 3-1.
Linux User Manager