- Release Notes and Announcements
- Release Notes
- Announcements
- Announcement on Changing External Network Links
- Interface Authentication Upgrade Announcement
- Maintenance Time Change from Local Time to Beijing Time
- Account Type and Permission Changes
- Product Architecture Name Change
- Disk Storage Space Composition Change
- Ending Support for Classic Network [2022.12.31]
- Backup Billing Start [2022.07.10]
- Ending Sale for Basic Edition 1-Core Specification [2022.03.07]
- User Guide
- Product Introduction
- Purchase Guide
- Getting Started
- Operation Guide
- Constraints and Limits
- Usage Specifications and Suggestions
- Maintaining Instance
- Renaming Instance
- Setting Instance Remarks
- Setting Instance Tag
- Setting Instance Project
- Modify Instance-level Character Set Collation
- Modify System Time Zone
- Setting Instance Maintenance Information
- Multi-AZ Disaster Recovery
- Restarting Instance
- Terminating Instance
- Migrating Across AZs
- Manual Primary-Secondary Switching
- Recycle Bin
- Adjusting Instance Configuration
- Read-Only Instance
- Network and Security
- Account Management
- Database Management
- Data Security
- Parameter Configuration
- Monitoring and Alarms
- Backup and Restoration
- Log Management
- Publish-Subscribe
- SSIS
- Data Migration (New)
- Data Migration (Legacy)
- Best Practice
- API Documentation
- History
- Introduction
- API Category
- Making API Requests
- Instance Management APIs
- CreateCloudDBInstances
- CreateCloudReadOnlyDBInstances
- ModifyInstanceEncryptAttributes
- UpgradeDBInstance
- RollbackInstance
- RestoreInstance
- RestartDBInstance
- ResetAccountPassword
- ModifyDBRemark
- ModifyDBName
- ModifyDBInstanceProject
- ModifyDBInstanceName
- ModifyAccountPrivilege
- InquiryPriceUpgradeDBInstance
- InquiryPriceCreateDBInstances
- DescribeZones
- DescribeRollbackTime
- DescribeRegions
- DescribeProductConfig
- DescribeFlowStatus
- DescribeDBs
- DescribeDBInstances
- DescribeAccounts
- DeleteDB
- DeleteAccount
- CreateDBInstances
- CreateDB
- CreateAccount
- TerminateDBInstance
- RecycleDBInstance
- CloneDB
- DescribeDBCharsets
- ModifyDatabaseMdf
- ModifyDatabaseCT
- ModifyDatabaseCDC
- DescribeDBsNormal
- ModifyInstanceParam
- DescribeInstanceParams
- DescribeInstanceParamRecords
- OpenInterCommunication
- DescribeDBInstanceInter
- DescribeBusinessIntelligenceFile
- DeleteBusinessIntelligenceFile
- CreateBusinessIntelligenceFile
- CreateBusinessDBInstances
- CloseInterCommunication
- Network Management APIs
- Backup APIs
- RunMigration
- ModifyMigration
- DescribeMigrations
- DescribeMigrationDetail
- DescribeBackups
- DeleteMigration
- CreateMigration
- CreateBackup
- ModifyBackupStrategy
- StartIncrementalMigration
- StartBackupMigration
- ModifyIncrementalMigration
- ModifyBackupMigration
- DescribeUploadBackupInfo
- DescribeIncrementalMigration
- DescribeBackupUploadSize
- DescribeBackupMigration
- DescribeBackupCommand
- DeleteIncrementalMigration
- DeleteBackupMigration
- CreateIncrementalMigration
- CreateBackupMigration
- DescribeBackupFiles
- Extended Event APIs
- Database APIs
- Other APIs
- Data Types
- Error Codes
- FAQs
- Overview
- Model Selection
- Pricing and Selection
- Connection and Network
- Account and Permission
- Backup and Rollback
- Data Migration
- Publish/Subscribe
- Read-Only Instance
- Version and Architecture Upgrade
- Disk Space and Specification Adjustment
- Monitoring and Alarms
- Log
- Parameter Modification
- Features
- Performance/Space/Memory
- Service Agreement
- Performance Evaluation
- Glossary
- Contact Us
- Release Notes and Announcements
- Release Notes
- Announcements
- Announcement on Changing External Network Links
- Interface Authentication Upgrade Announcement
- Maintenance Time Change from Local Time to Beijing Time
- Account Type and Permission Changes
- Product Architecture Name Change
- Disk Storage Space Composition Change
- Ending Support for Classic Network [2022.12.31]
- Backup Billing Start [2022.07.10]
- Ending Sale for Basic Edition 1-Core Specification [2022.03.07]
- User Guide
- Product Introduction
- Purchase Guide
- Getting Started
- Operation Guide
- Constraints and Limits
- Usage Specifications and Suggestions
- Maintaining Instance
- Renaming Instance
- Setting Instance Remarks
- Setting Instance Tag
- Setting Instance Project
- Modify Instance-level Character Set Collation
- Modify System Time Zone
- Setting Instance Maintenance Information
- Multi-AZ Disaster Recovery
- Restarting Instance
- Terminating Instance
- Migrating Across AZs
- Manual Primary-Secondary Switching
- Recycle Bin
- Adjusting Instance Configuration
- Read-Only Instance
- Network and Security
- Account Management
- Database Management
- Data Security
- Parameter Configuration
- Monitoring and Alarms
- Backup and Restoration
- Log Management
- Publish-Subscribe
- SSIS
- Data Migration (New)
- Data Migration (Legacy)
- Best Practice
- API Documentation
- History
- Introduction
- API Category
- Making API Requests
- Instance Management APIs
- CreateCloudDBInstances
- CreateCloudReadOnlyDBInstances
- ModifyInstanceEncryptAttributes
- UpgradeDBInstance
- RollbackInstance
- RestoreInstance
- RestartDBInstance
- ResetAccountPassword
- ModifyDBRemark
- ModifyDBName
- ModifyDBInstanceProject
- ModifyDBInstanceName
- ModifyAccountPrivilege
- InquiryPriceUpgradeDBInstance
- InquiryPriceCreateDBInstances
- DescribeZones
- DescribeRollbackTime
- DescribeRegions
- DescribeProductConfig
- DescribeFlowStatus
- DescribeDBs
- DescribeDBInstances
- DescribeAccounts
- DeleteDB
- DeleteAccount
- CreateDBInstances
- CreateDB
- CreateAccount
- TerminateDBInstance
- RecycleDBInstance
- CloneDB
- DescribeDBCharsets
- ModifyDatabaseMdf
- ModifyDatabaseCT
- ModifyDatabaseCDC
- DescribeDBsNormal
- ModifyInstanceParam
- DescribeInstanceParams
- DescribeInstanceParamRecords
- OpenInterCommunication
- DescribeDBInstanceInter
- DescribeBusinessIntelligenceFile
- DeleteBusinessIntelligenceFile
- CreateBusinessIntelligenceFile
- CreateBusinessDBInstances
- CloseInterCommunication
- Network Management APIs
- Backup APIs
- RunMigration
- ModifyMigration
- DescribeMigrations
- DescribeMigrationDetail
- DescribeBackups
- DeleteMigration
- CreateMigration
- CreateBackup
- ModifyBackupStrategy
- StartIncrementalMigration
- StartBackupMigration
- ModifyIncrementalMigration
- ModifyBackupMigration
- DescribeUploadBackupInfo
- DescribeIncrementalMigration
- DescribeBackupUploadSize
- DescribeBackupMigration
- DescribeBackupCommand
- DeleteIncrementalMigration
- DeleteBackupMigration
- CreateIncrementalMigration
- CreateBackupMigration
- DescribeBackupFiles
- Extended Event APIs
- Database APIs
- Other APIs
- Data Types
- Error Codes
- FAQs
- Overview
- Model Selection
- Pricing and Selection
- Connection and Network
- Account and Permission
- Backup and Rollback
- Data Migration
- Publish/Subscribe
- Read-Only Instance
- Version and Architecture Upgrade
- Disk Space and Specification Adjustment
- Monitoring and Alarms
- Log
- Parameter Modification
- Features
- Performance/Space/Memory
- Service Agreement
- Performance Evaluation
- Glossary
- Contact Us
SQL Server supports the switch between primary database and secondary database of instances. When a malfunction occurs, the system switches the secondary database to the primary to ensure system availability and data integrity. This represents the automatic switch the system performs under special circumstances such as failures. Additionally, you can manually perform the switch through the console.
Background
In enterprise-level applications, the database often forms a critical component of the business system. Any failure or downtime can have serious implications on business operations. To safeguard system availability and data integrity, high-availability solutions such as primary-secondary replication are implemented. Primary-secondary switch is a crucial technical method within the replication scheme, which enables a quick transition to the backup database when the main database encounters a problem, averting business interruptions and data losses.
Prerequisites
The instance is configured with a two-node cloud disk architecture.
Note:
If a two-node local disk architectural instance requires a manual primary-secondary switch, please submit a ticket for assistance.
The instance is in running status, with no ongoing tasks.
Points of Attention
During the primary-secondary database switch, a momentary disconnection occurs. We recommend that you run the switch during off-peak business hours and ensure your application possesses a reconnection mechanism.
After the primary-secondary database switch, the instance connection address remains the same. The original primary instance converts into a secondary instance, and the application connects automatically to the new primary instance (namely, the original secondary instance).
By default, the data replication mode between the primary and secondary databases is set to asynchronous replication.
Use Limits
If there are read-only instances under the primary instance or if the primary instance employs the publish-subscribe feature, then the primary-secondary switch is not supported.
The steps are as follows:
1. Log in to the TencentDB for SQL Server console. In the instance list, click an instance ID or Manage in the operation column to access the instance details page.
2. On the instance details page, click Primary-Replica Switch after Availability Info.
3. In the Primary/Secondary switch pop-up window, select the switch time. A momentary disconnection will occur when AZs are switched. Ensure your business possesses a reconnection mechanism checkbox, and then click Confirm.
Switch Immediately: The switch will occur immediately upon the completion of data synchronization between the primary and secondary AZs.
During Maintenance Time: The switch will occur during the next maintenance window once the data synchronization between the primary and secondary AZs is complete. If the switch is scheduled for within the maintenance window, but urgent switch is needed due to unforeseen circumstances, click Switch Now in the Operation column for the corresponding instance in the TencentDB for SQL Server console. For operations related to setting the instance maintenance time, see Setting Instance Maintenance Information.
Primary/Secondary Switch Log
SQL Server supports viewing primary/secondary switch logs, assisting you in understanding the detailed time and switch method, determining whether the switch is successful, and optimizing the switch strategy. For detailed operational guidance, please refer to Querying Primary/Secondary Switch Logs.
Hotspot Issues
Will an instance address change after the successful switch of the primary and secondary databases of the instance?
The instance address remains the same after the switch. The original primary instance acts as a secondary one, with applications automatically connecting to the new primary instance (namely, the original secondary instance).
After a manual switch, if an upgrade or the upgrade of configurations is performed on an instance, will this affect or reset the information of the primary and secondary availability zones?
The switch will not affect or reset the information of the primary and secondary availability zones.
How can the primary and secondary databases of the primary instance be switched when read-only instances are mounted under the primary instance?
The primary instance with read-only instances does not support primary-secondary switch. If you still need to switch the primary and secondary databases, you need to release the read-only instances first, then switch the primary and secondary databases. After that, you can repurchase read-only instances.
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