How to Build a Real‑Time Data Guard System for Dameng Database

Introduction

In certain work scenarios the Dameng database data‑guard feature may be required; this article explains how to build the Dameng data‑guard service.

Environment

The setup uses three machines: one primary, one standby, and one monitor. Primary and standby databases must be initialized beforehand.

1. Data Preparation

Ensure primary and standby data stay consistent using the dmrman offline backup/restore method. Stop the primary and perform a full RMAN backup.

./dmrman CTLSTMT="BACKUP DATABASE '/dm8/data/DMDW/dm.ini' FULL TO BACKUP_FILE1 BACKUPSET '/dm8/backup/BACKUP_FILE_01'"

2. Primary Configuration Files

dm.ini

INSTANCE_NAME = GRP1_RT_01
PORT_NUM = 32141 # Database instance listening port
DW_INACTIVE_INTERVAL = 60 # Guard message timeout
ALTER_MODE_STATUS = 0 # Disallow manual mode/status/OGUID changes
ENABLE_OFFLINE_TS = 2 # Disallow standby OFFLINE tablespace
MAL_INI = 1 # Enable MAL system
ARCH_INI = 1 # Enable archive configuration
RLOG_SEND_APPLY_MON = 64 # Log send statistics

dmmal.ini

MAL_CHECK_INTERVAL = 5 # MAL link check interval
MAL_CONN_FAIL_INTERVAL = 5 # MAL link failure interval
[MAL_INST1]
MAL_INST_NAME = GRP1_RT_01 # Same as INSTANCE_NAME in dm.ini
MAL_HOST = 192.168.0.141 # MAL system IP
MAL_PORT = 61141 # MAL system port
MAL_INST_HOST = 192.168.1.131 # External service IP
MAL_INST_PORT = 32141 # External service port (same as PORT_NUM)
MAL_DW_PORT = 52141 # Guard process listening port
MAL_INST_DW_PORT = 33141 # Guard process TCP port
[MAL_INST2]
MAL_INST_NAME = GRP1_RT_02
MAL_HOST = 192.168.0.142
MAL_PORT = 61142
MAL_INST_HOST = 192.168.1.132
MAL_INST_PORT = 32142
MAL_DW_PORT = 52142
MAL_INST_DW_PORT = 33142

dmarch.ini

[ARCHIVE_REALTIME]
ARCH_TYPE = REALTIME # Real‑time archive type
ARCH_DEST = GRP1_RT_02 # Destination instance for real‑time archive
[ARCHIVE_LOCAL1]
ARCH_TYPE = LOCAL # Local archive type
ARCH_DEST = /dm/data/DAMENG/arch # Local archive path
ARCH_FILE_SIZE = 128 # Max file size (MB)
ARCH_SPACE_LIMIT = 0 # No space limit

dmwatcher.ini

[GRP1]
DW_TYPE = GLOBAL # Global guard type
DW_MODE = AUTO # Automatic switch mode
DW_ERROR_TIME = 10 # Remote guard fault detection time
INST_RECOVER_TIME = 60 # Primary guard restart interval
INST_ERROR_TIME = 10 # Local instance fault detection time
INST_OGUID = 453331 # Unique OGUID for the guard system
INST_INI = /dm/data/DAMENG/dm.ini # Path to dm.ini
INST_AUTO_RESTART = 1 # Enable auto‑restart
INST_STARTUP_CMD = /dm/bin/dmserver # Startup command
RLOG_SEND_THRESHOLD = 0 # Primary log send threshold (disabled)
RLOG_APPLY_THRESHOLD = 0 # Standby log apply threshold (disabled)

3. Start Primary

./dmserver /dm/data/DAMENG/dm.ini mount

4. Set OGUID on Primary

SP_SET_PARA_VALUE(1, 'ALTER_MODE_STATUS', 1);
sp_set_oguid(453331);
SP_SET_PARA_VALUE(1, 'ALTER_MODE_STATUS', 0);

5. Change Primary Mode

alter database primary;

6. Standby Configuration Files

dm.ini (standby)

INSTANCE_NAME = GRP1_RT_02
PORT_NUM = 32142 # Database instance listening port
DW_INACTIVE_INTERVAL = 60
ALTER_MODE_STATUS = 0
ENABLE_OFFLINE_TS = 2
MAL_INI = 1
ARCH_INI = 1
RLOG_SEND_APPLY_MON = 64

dmmal.ini (standby)

MAL_CHECK_INTERVAL = 5
MAL_CONN_FAIL_INTERVAL = 5
[MAL_INST1]
MAL_INST_NAME = GRP1_RT_01
MAL_HOST = 192.168.0.141
MAL_PORT = 61141
MAL_INST_HOST = 192.168.1.131
MAL_INST_PORT = 32141
MAL_DW_PORT = 52141
MAL_INST_DW_PORT = 33141
[MAL_INST2]
MAL_INST_NAME = GRP1_RT_02
MAL_HOST = 192.168.0.142
MAL_PORT = 61142
MAL_INST_HOST = 192.168.1.132
MAL_INST_PORT = 32142
MAL_DW_PORT = 52142
MAL_INST_DW_PORT = 33142

dmarch.ini (standby)

[ARCHIVE_REALTIME]
ARCH_TYPE = REALTIME
ARCH_DEST = GRP1_RT_01 # Real‑time archive target (primary)
[ARCHIVE_LOCAL1]
ARCH_TYPE = LOCAL
ARCH_DEST = /dm/data/DAMENG/arch
ARCH_FILE_SIZE = 128
ARCH_SPACE_LIMIT = 0

dmwatcher.ini (standby)

[GRP1]
DW_TYPE = GLOBAL
DW_MODE = AUTO
DW_ERROR_TIME = 10
INST_RECOVER_TIME = 60
INST_ERROR_TIME = 10
INST_OGUID = 453331
INST_INI = /dm/data/DAMENG/dm.ini
INST_AUTO_RESTART = 1
INST_STARTUP_CMD = /dm/bin/dmserver
RLOG_APPLY_THRESHOLD = 0

7. Start Standby

./dmserver /dm/data/DAMENG/dm.ini mount

8. Set OGUID on Standby

SP_SET_PARA_VALUE(1, 'ALTER_MODE_STATUS', 1);
sp_set_oguid(453331);
SP_SET_PARA_VALUE(1, 'ALTER_MODE_STATUS', 0);

9. Change Standby Mode

SP_SET_PARA_VALUE(1, 'ALTER_MODE_STATUS', 1);
alter database standby;
SP_SET_PARA_VALUE(1, 'ALTER_MODE_STATUS', 0);

10. Monitor Configuration

MON_DW_CONFIRM = 1 # Confirmation monitor mode
MON_LOG_PATH = /dm/data/log
MON_LOG_INTERVAL = 60
MON_LOG_FILE_SIZE = 32
MON_LOG_SPACE_LIMIT = 0
[GRP1]
MON_INST_OGUID = 453331
MON_DW_IP = 192.168.0.141:52141
MON_DW_IP = 192.168.0.142:52142

11. Start Guard Processes

./dmwatcher /dm/data/DAMENG/dmwatcher.ini
./dmmonitor /dm/data/dmmonitor.ini

Result

When all steps and configurations are correct, the primary‑standby real‑time data‑guard system is operational; the show command on the monitor displays all instances and guard processes in the Open state, indicating normal operation.