6 configuring data protection modes and redo transport services

Configuring Data Protection Modes and Redo Transport Services... After completing this lesson, you should be able to do the following: • Describe the data protection modes • Change the d

Configuring Data Protection Modes

and Redo Transport Services

After completing this lesson, you should be able to do the following:

• Describe the data protection modes

• Change the data protection mode of your configuration

• Modify redo transport services to serve your needs

Data Protection Modes and Redo Transport Modes

• A data protection mode requires a specific redo

transport mode.

• A redo transport mode alone does not define a data protection mode.

Defining the Redo Transport Mode

Use the attributes of LOG_ARCHIVE_DEST_n:

• ARCH and LGWR

– Specify that either the archiver process or the log writer

process is responsible for transmitting redo to the standby destination

– ARCH is the default.

• SYNC and ASYNC (LGWR only)

– Specify that network I/O operations are to be performed synchronously or asynchronously when using LGWR

– SYNC is the default.

• AFFIRM and NOAFFIRM

– Ensure that redo has been successfully written to disk on

Setting the Redo Transport Mode

Click Edit to access the Edit Standby Database Properties

Setting the Redo Transport Mode

Select the mode from

the Log Transport Mode

list.

Data Protection Modes

• Three data protection modes:

Maximum Protection

• Enables zero data loss

• Redo data must be written to both the local online redo

log and the standby redo log on at least one standby database.

• Primary database shuts down if a fault prevents it from

writing its redo stream to at least one remote standby redo log.

Maximum Availability

• Enables zero data loss

• Provides the highest possible level of data protection

without compromising the availability of the primary

database

• Redo data must be written to both the local online redo

log and the standby redo log on at least one standby

database.

• Primary database does not shut down if a fault prevents

it from writing its redo stream.

Maximum Performance

• Default level of data protection

• Provides the highest possible level of data protection

without affecting the performance of the primary

database

• Transactions can commit as soon as the redo data is

written to the local online redo log.

• Redo stream is written asynchronously with respect to

the commitment of the transactions that create the redo data.

Setting the Data Protection Mode

Click the Protection Mode

link.

Setting the Data Protection Mode

Setting the Data Protection Mode

by Using the CLI

1 Configure standby redo logs.

2 Set the LogXptMode property (if necessary).

3 Set the data protection mode.

DGMGRL> EDIT DATABASE 'site1_edrsr8p1' SET PROPERTY 'LogXptMode'='SYNC';

DGMGRL> EDIT CONFIGURATION SET PROTECTION MODE AS MAXAVAILABILITY;

Setting the Protection Mode

Delaying the Application of Redo

Delaying the application of redo helps safeguard against:

Using Enterprise Manager to Delay

the Application of Redo

Specify the delay in

minutes.

Setting LOG_ARCHIVE_DEST_n

to Delay the Application of Redo

Use the attributes of LOG_ARCHIVE_DEST_n to control the

application of redo:

• DELAY: number of minutes to delay application of redo (default: 30 minutes)

Using Flashback Database Instead of Apply Delay

Additional Attributes That Affect

Redo Transport Services

Using the ALTERNATE Attribute

• Can specify one alternate destination for the

LOG_ARCHIVE_DEST_n parameter

• Allow a failed destination to change destinations

– Disk full: switch to new disk

– Oracle Net link fails: switch to new network link

• Require REOPEN=0 or MAX_FAILURE

• Enabled with LOG_ARCHIVE_DEST_STATE_n

log_archive_dest_3='SERVICE=stby1_path1 REOPEN=0 ALTERNATE=LOG_ARCHIVE_DEST_4'

log_archive_dest_4='SERVICE=stby1_path2 REOPEN=0 OPTIONAL'

log_archive_dest_state_3=ENABLE

Using the MAX_FAILURE Attribute

Using the NET_TIMEOUT Attribute

• Enables the LGWR process to avoid a network timeout

issue

• Valid with SYNC or ASYNC destinations

• Value supplied is the number of seconds to wait.

• Range of values for NET_TIMEOUT: 15 to 1200

• Default: 180

• Use caution in maximum protection mode.

log_archive_dest_2='SERVICE=o10g2 LGWR SYNC

NET_TIMEOUT=30'

Using the REOPEN Attribute

• REOPEN[=seconds]

– Minimum number of seconds to wait before retrying a

failed destination at log switch

– Failures can be network failures, quota exceptions, disk full, and so on.

– Default: 300 seconds (5 minutes)

Optimized Asynchronous Redo Transmission

FAL

RFS

MRP or LSP (MRP only)

ARC1 ARC2

Enabling Multiple Connections for Remote Archival of Redo

LOG_ARCHIVE_DEST_3=

'SERVICE=detroit MAX_CONNECTIONS=5'

The following conditions must be met to enable this feature:

• Remote archiving is performed to disk.

• LOG_ARCHIVE_LOCAL_FIRST must be set to TRUE (default).

In this lesson, you should have learned how to:

• Describe the data protection modes

• Change the data protection mode of your configuration

• Modify redo transport services to suit your needs

• Delay the application of redo

• Use additional transport services attributes

Practice 6: Overview

This practice covers the following topics: