datablogs: Troubleshooting
Showing posts with label Troubleshooting. Show all posts
Showing posts with label Troubleshooting. Show all posts

Monday, January 31, 2022

Migrate Azure MySQL Database to Amazon RDS for MySQL Using MySQL Replication

Its Nightmare Story struggled a lot to reduce the cut over time with Azure MySQL to AWS Migration MySQL Migration.

Tested Methods, 

  1. Backup and Restore - Its took 6 hours to complete
  2. AWS DMS - Text Data truncated and timestamp column data was 6 hours behind from the source

But Nothing helped due to Bugs, features unavailable etc.., But by default replication helped us to work. 

Two types replication available in Azure MySQL ,

1.GTID based Replication

    This is we already discussed with multiple topics in our blog for GCP cloud, also we will explain how to configure GTID based replication from Azure MySQL to AWS RDS in next blog

MySQL GTID Replication and lower_case_table_names

Multi Source Replication from GCP Cloud MySQL to Percona XtraDB Cluster

2.Binlog position-based replication

    We are performing binlog position-based replication to cut over the application in this blog

Environment Setup 

Below POC environment setup done for testing 
  • Azure MySQL 5.6.4 General Purpose instance launched with minimal configuration
  • AWS RDS for MySQL 5.7 launched with customized parameter group 
  • Network connectivity between Azure PaaS and AWS PaaS Service

Once environment is up and running, modify the below server parameters in both side 

Below values needs to update in Both environments, 

Azure MySQL: 

  • replicate_wild_ignore_table=mysql.%,information_schema.%,performance_schema.%,sys.%
  • binlog_row_image = FULL
  • binlog_expire_logs_seconds = 1440


  • time_zone = Same as Azure MySQL
  • binlog_format = ROW
  • collation and character_set parameters = Same as Azure MySQL

Now both server is ready to configure the replication

Pre-Steps to configure the replication

1.Let’s verify and take a note of binlog position in Azure MySQL   

 mysql> show master status.


| File                        | Position    | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |


| mysql-bin.00865 | 52884741       |              |                  |                   |


1 row in set (0.00 sec)

2.Create a replication user with necessary privileges

CREATE ‘repluser’@’%’ IDENTIFIED BY ‘datablogs123’.



GRANT SELECT, CONNECT ON *.* TO ‘repluser’@’%’;


3.Using mysqldump start the schema backup and followed by data backup 

mysqldump -h -u repluser@datablogs -p datablogsprod --no-data --routines --triggers --events > datablogsprodmeta.sql

mysqldump -h -u repluser@datablogs -p datablogsprod --routines --triggers --events --skip-add-drop-table  --max_allowed_packet=1024M --single-transaction  > datablogsproddata.sql

4.Once backup is completed restore the data into MySQL RDS , 

mysql -h -u repluser -p datablogsprod  < datablogsprodmeta.sql

mysql -h -u repluser -p datablogsprod  --max_allowed_packet=1024M  < datablogsproddata.sql

Configuring the replication 

In Amazon MySQL set the external master with the help of Step 1 binlog file name and binlog position 

CALL mysql.rds_stop_replication;

CALL mysql.rds_reset_external_master;

CALL mysql.rds_set_external_master ('', 3306, 'repluser@datablogs', 'repluser', 'mysql-bin.00865', 52884741, 0);

CALL mysql.rds_start_replication;

Once executed start the replication and check the slave status in RDS ,

    mysql> show slave status \G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: Master_User: repluser@datablogs Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-bin.00865 Read_Master_Log_Pos: 52884741 Relay_Log_File: relaylog.000004 Relay_Log_Pos: 273 Relay_Master_Log_File: mysql-bin.00865 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: datablogsprod Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: mysql.plugin,mysql.rds_monitor,mysql.rds_sysinfo,innodb_memcache.cache_policies,mysql.rds_history,innodb_memcache.config_options,mysql.rds_configuration,mysql.rds_replication_status Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 52884741 Relay_Log_Space: 19742 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1053643462 Master_UUID: 787858b4-a021-11ea-b894-97f71069e028 Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec)

Post Validation and troubleshooting steps of Azure MySQL Replication

Validate the data and tables counts between Azure MySQL and MySQL RDS 

If we get any errors related with system schema in the Azure use the following method to fix it , we got same error like below ,

Can't find 'mysql.__firewallrules__' doesnt exist 

We can skip the error with below commands in MySQL RDS , 

CALL mysql.rds_stop_replication;
CALL mysql.rds_skip_repl_error;
CALL mysql.rds_start_replication;

But in MySQL RDS Row by row only errors will be skip and it will take long time to do it , follow the below method and check the binlog position until for the DML , DDL queries are captured in binlog 

SHOW BINLOG EVENTS IN 'mysql-bin.00865' FROM 52884567 LIMIT 10 \G

Note : Based on the error modify the binlog file and position in above command

Once found the binlog position repeat the configuring replication step

Now All set for Azure to AWS data sync , now its ready for application cutover with zero downtime !!!


Sunday, July 12, 2020

[SQLState XX000] ERROR: User arn:aws:redshift:ap-south-1:316720341464:dbuser:redshift-cluster-1/analytics is not authorized to assume IAM Role arn:aws:iam::323232323:role/aws-access-for-redshift

While Configure Data Migration Service between Redshift and any kind of heterogeneous source , we come across these issues often .

Error looks like an IAM policy is missing for attached , so we straightly move into IAM console granted AmazonS3FullAccess AmazonRedshiftFullAccess , then restart failed DMS tasks .

But no luck , still we are getting same issue

When we looking into Redshift IAM role , customer have been added custom roles with permissions . so it is missing trusted entities for both and

Move into Trust relationships tab in custom role and edit trust relationship as below ,

  "Version": "2012-10-17",
  "Statement": [
      "Sid": "",
      "Effect": "Allow",
      "Principal": {
        "Service": [
      "Action": "sts:AssumeRole"
after adding trusted entities
Attached policies for DMS tasks

Once we update trust policy , able to load data between MySQL to Redshift

Remember to troubleshoot DMS tasks in depth , always enable detailed debug in cloudwatch logs