Oracle Database Administration for Microsoft SQL Server DBAs part 15 pps

If Oracle server is not configured for this, errors will ## occur in connecting.But setting NONE first will only disable the local ## support using Windows credentials SQLNET.AUTHENTICAT

locations that can be centrally managed All that is required on the client side is the information for the Oracle Internet Directory For the connection

to the Oracle Internet Directory to look up the location of the database, an ldap.ora file is needed in the ORACLE_HOME/network/admin directory Here is an example of an ldap.ora file:

DEFAULT_ADMIN_CONTEXT = "ou=databases,dc=company1,dc=com"

DIRECTORY_SERVICES = (ldap_server.company1.com:389:636)

DIRECTORY_SERVER_TYPE = OID

The sqlnet.ora file has parameters for using the Oracle Internet Directory, tnsnames.ora, EZCONNECT (easy connection naming method without tnsnames.ora), and the default domain There is also expiration time of the client connection, and this can be used to trace client sessions Here is a list

of some of these parameters in a sample sqlnet.ora:

NAMES.DEFAULT_DOMAIN = (US.COM)

###It will try these connections in this order path first

### LDAP, etc.

NAMES.DIRECTORY_PATH = (LDAP, TNSNAMES, EZCONNECT)

## NTS allows oracle to use current Windows domain credentials to

## authenticate If Oracle server is not configured for this, errors will

## occur in connecting.But setting NONE first will only disable the local

## support using Windows credentials

SQLNET.AUTHENTICATION_SERVICES = (NONE,NTS)

##These parameters can be uncommented to start the tracing

##TRACE_LEVEL_CLIENT=4

##TRACE_FILE_CLIENT=client_sqlnet.trc

##TRACE_DIRECTORY_CLEINT=D:\oracle\trace

## Time is specified in minutes for the expire time but this

## would be set on the database server

SQLNET.EXPIRE_TIME=30

As seen with the NTS setting in this file, the Windows domain credentials would be useful for defining externally authenticated users in the database, and then setting AUTHENTICATION_SERVICES = ( NTS) will allow for passing the Windows credentials through to the database Since the sqlnet.ora file is on both the client and server side, there might be some parameters that are set for the server, but these may still have an effect on the client For example, EXPIRE_TIME will time out sessions

The most common issues when setting up a connection to the database

stem from incorrect information in the connection string, tnsnames.ora file,

or sqlnet.ora file I have even tried to track down a connection issue, only to discover that there were two different tnsnames.ora files, and the one with

the incorrect information was being looked at first because it came up first

in the path environment variable

As you’ve seen, the sqlnet.ora file also has information on authentication and the domain If this doesn’t match up with your environment, it might

be looking for a database in a different domain, or even looking for a

tnsnames.ora file when it is set up to use LDAP

These files can be edited manually, but typing issues may cause trouble

if the files were generated by an Oracle configuration tool

It is also possible that TNS errors will come up if you are logging in

to SQL*Plus and the ORACLE_SID variable is not set or you are using

usernameORACLE_SIDto define which database the client is attempting

to connect to

JDBC Connections

The applications and clients normally set up the connections, and the

details of the host, database name, and port should be all that they need to

get started However, they may sometimes need assistance with connections and using different drivers

For JDBC drivers, there are thin and thick clients There is not much

difference between the two, except that the thick client has the ability to use the tnsnames.ora file, and the thin client might not have these structures set

up because just the drivers were installed

url="jdbc:oracle:thin:host:port:sid"

url="jdbc:oracle:thin:(DESCRIPTION=

(LOAD_BALANCE=on)

(ADDRESS=(PROTOCOL=TCP)(HOST=orasrvrac1-vip)(PORT=1521))

(ADDRESS=(PROTOCOL=TCP)(HOST=orasrvrac2-vip)(PORT=1521))

(COONECT_DATA=(SERVICE_NAME=RACDB)))"

## thick client can use the database name in the tnsnames.ora file

url="jdbc:oracle:orci:MMDEV1"

Aliases

A SQL Server instance can have an alias to use a client network utility Even

a local instance with no name can get a different name to use as an alias

Chapter 5: DBA Tools 123

The same is true for Oracle databases A database alias can be set up in the tnsnames.ora file

DB_ALIAS =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = TCP)(HOST = oraserver1)(PORT = 1521)) (CONNECT_DATA =

(SERVER = DEDICATED)

(SERVICE_NAME = MMDEV1)

)

)

In this example, DB_ALIAS will actually connect to the MMDEV1 database

It is that simple to create an alias, and it obviously doesn’t change the actual name of the database

CAUTION

In the tnsnames.ora file, having the same name

listed twice can cause connection issues Even

if the details are the same for both of the

listings, duplicates can cause problems

connecting

My Oracle Support

Most of these tools discussed in this chapter are used on a daily basis to manage the database and log in to databases I consider My Oracle Support

a tool, because not only does it have a knowledge base for commands, issues, and possible errors, but it also has the Configuration Manager for assistance in applying patches and upgrades It also offers a health check monitor that provides some suggestions based on the configurations in the databases

There is community out there, and through My Oracle Support, you can have discussions with other DBAs In addition to those you can find through the message areas in My Oracle Support, other Oracle user communities are great resources for information and networking User groups such as the Independent Oracle User Group (IOUG) have real DBAs performing real tasks, and they are willing to share their experiences and help you to work through issues

In this chapter, we have discussed several different tools available to Oracle DBAs Some of the tools are geared more toward the management of the

database servers; others might be more focused on development Both types are useful for DBAs There are several areas to explore in OEM and SQL

Developer to make you more productive as a DBA And don’t forget that

even though it is good to have an easy interface to use, it’s also handy to be able to run simple scripts and queries in a regular SQL*Plus session

However, it’s not too useful to have these tools if you cannot connect

them to the database So, we discussed how to get connected and took a

look at the pieces that are needed to connect, including the tnsnames.ora

and sqlnet.ora files

Chapter 5: DBA Tools 125

6

Database Backup,

Restore, and

Recovery

A s a DBA, you already know the importance of databasebackups You have probably developed your own backup

strategies and disaster recovery plans for the SQL Server databases you support

You also know that being able to back up a database is just part of the job You need to manage the backups and know which backup pieces to use to be able to recover quickly and easily Testing restore procedures validates that you have solid, usable backups, and also lets you develop restore scripts to save for a rainy day

In this chapter, you will learn about the set of backup and recovery tools available for the Oracle platform This will help you to develop your backup and recovery strategies for your Oracle databases

Backing Up Databases

Sometimes your job as a DBA may seem like all you are doing is verifying that backups are running successfully and restoring testing environments with those backups This is definitely an important task for the system DBA, and backups are key to providing a secure and reliable database environment

Backup Strategies

As a DBA, no matter which database platform you are administering, you need to plan a backup strategy that makes recovery a simple process and fits the needs of the business There are several strategies for backing up databases, depending on resources, the importance of the data, and if it is needed for recovery and running the business

For SQL Server databases, creating maintenance plans sets up some backup strategies The SQL Server database recovery model setting of either SIMPLE or FULL also determines if log backups are needed As the database changes or grows, plans to compress, write to tape, and allocate threads to use for the backup are all taken into consideration

The Oracle DBCA also has a step to set up maintenance plans, which include backup settings You also have the option to create the database in NOARCHIVELOG mode, which is similar to the SQL Server SIMPLE option,

or ARCHIVELOG mode, which is like the FULL option

It is important to be able to communicate the options for backup and

restore strategies to the business owners Understanding the options, the

resources needed (disks, tapes, and so on), and what data loss would mean

to the business are key to being able to convey how the restore options

would benefit the business This will help you and the business owners to

develop the best plan to balance the resources and protect the data assets

What are you protecting against? You probably have been setting up

backup strategies to protect against hardware failures, data loss, changes

that have gone wrong, and disasters Running backup database and

transaction logs, and saving copies to disk and tape with certain retention

policies are all part of this plan

So what options are available in Oracle to protect the data against those

“oops” or “oh no” moments? Besides the backups, there are exports, a

recycle bin, and a way to flashback queries and even the database We’ll

start with some of the commands for backing up the database, and then

progress through the other options

Backup and Restore Commands

The basic commands for backing up and restoring Oracle databases should

look familiar to SQL Server DBAs Let’s start with the SQL Server command

to back up a database:

backup database customer_db to

disk ='E:\mssql\bkups\customer_db_02022010.bak'

backup log customer_db to

disk='E:\mssql\bkups\customer_db_log_02022010.trn'

This will take care of the SQL Server database and log backups, and

write the backup file to disk

In Oracle, you use a Recovery Manager (RMAN) command, like this:

RMAN> run {

allocate channel disk1 device type disk;

backup database plus archivelog;

}

This command will back up the database with the archive logs and write the backup file to disk

Chapter 6: Database Backup, Restore, and Recovery 129

Here is the SQL Server command to restore a database:

restore database customer_db from

disk ='E:\mssql\bkups\customer_db_02022010.bak'

The Oracle RMAN command is basically the same:

RMAN> run {

allocate channel disk1 device type disk;

restore database;

}

Both database platforms can perform “hot backups” while the database

is up and available, when it’s possible that changes are happening as the backup is running The transaction and archive logs keep these changes, so these logs must be part of the backup set

NOTE

RMAN puts the database (datafiles and

tablespaces) in backup mode when it runs the

backups If you’re not using RMAN, you’ll need

to issue ALTER DATABASE BEGIN BACKUP

before being able to do a hot backup of the

database

Typically, 24/7 access to the database is required, so hot backups are made However, there might be opportunities to take a cold backup when the downtime is available, such as before an upgrade or hardware move This will get a full backup, so the transaction and archive logs do not need

to be handled In SQL Server, if the instance services are shut down for a cold backup, the files can be copied over The same is true for Oracle databases This script runs a cold backup:

RMAN> run {

shutdown immediate

startup mount

allocate channel disk1 device type disk;

backup database;

}

Looking at the script, you may wonder why there is a startup The

startup mountcommand will allow RMAN to read the control files to

know which datafiles need to be backed up The database server is still not

available, so the files can be copied and backed up by RMAN in this “cold”

state

Since the database is down for a cold backup, the datafiles can be

copied without using RMAN Scripts can be written using operating system

commands to just copy the datafiles to another location, tape, or another

mount point while the database is down A shell script or batch file can shut down the database, and then cp/copy commands can be issued to copy the datafiles, or a file system backup can be done This type of cold backup

would not need the database in mount state, because it wouldn’t be using

the control file, as RMAN does

As you can see from the examples, RMAN is a big part of the backup

and restore strategies for Oracle databases RMAN can be used through the

command line as well as OEM We’ve skipped over a few pieces in these

examples As you’ll learn next, RMAN requires some configuration to be

able to run backups

RMAN Configuration for Backups

RMAN is installed with the Oracle software and placed in the ORACLE_

HOME/bin/ directory RMAN can use a catalog to track and manage the

backups, or it can use the control file of the database for this purpose

A database must be available to be able to create the schema needed

for the RMAN catalog One catalog can manage the backups of several

databases, but the catalog should be at the same database version as the

databases being backed up

To configure RMAN, create a user to be catalog owner, and grant that

user a quota on the tablespace where the schema is going to live, as well as

the RECOVERY_CATALOG_OWNER role Next, create the catalog using the

RMAN command line:

>rman

RMAN> connect target

connected to target database: DBDEV1 (DBID=280973718)

DBDEV1 will be the database that will have the catalog schema.

Chapter 6: Database Backup, Restore, and Recovery 131