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Displaying posts with tag: Failover Process (reset)

Dec

2019

Re-Slaving a Crashed MySQL Master Server in Semisynchronous Replication Setup

Posted by ScaleGrid.io on Mon 09 Dec 2019 20:53 UTC
Tags:

Backup, database, cloud, High Availability, Developer, howto, binary logs, mysql replication, data integrity, restore, master-slave, backup snapshot, mysql Database, MySQL, replica set, MySQL GTID, semisynchronous replication, MySQL Hosting, ScaleGrid, Failover Process, Automated Tools, Crashed Master, Crashed MySQL, Data Inconsistency, Detect Extra Transactions, Extra Transactions, Failed Transaction, Fix Transactions, GTID_SUBSET, MySQL Master Server, New MySQL Master, Recovered Master, Recovered MySQL, Replication Error, Restore the Data

In a MySQL 5.7 master-slave setup that uses the default semisynchronous replication setting for rpl_semi_sync_master_wait_point, a crash of the master and failover to the slave is considered to be lossless. However, when the crashed master comes back, you may find that it has transactions that are not present in the current master (which was previously a slave). This behavior may be puzzling, given that semisynchronous replication is supposed to be lossless, but this is actually an expected behavior in MySQL. Why exactly this happens is explained in full detail in the …

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Jan

2019

MySQL High Availability Framework Explained – Part II: Semisynchronous Replication

Posted by ScaleGrid.io on Tue 08 Jan 2019 17:43 UTC
Tags:

sql, Learning, database, cloud, High Availability, data, Developer, howto, mysql replication, CAP Theorem, data consistency, MySQL, Performance, node, mysql high availability, synchronous replication, mysql deployments, asynchronous replication, MySQL settings, replica set, replication lag, semisynchronous replication, multi-threaded slaves, SQL thread, MySQL Hosting, HA Framework, High Availability Framework, Binary Log Entries, Execution Speed, Failover Process, Master-Slave Configuration, MySQL Master, MySQL Slaves, Network Partition, Parallel Threads, Single-Threaded Slaves

In Part I, we introduced a High Availability (HA) framework for MySQL hosting and discussed various components and their functionality. Now in Part II, we will discuss the details of MySQL semisynchronous replication and the related configuration settings that help us ensure redundancy and consistency of the data in our HA setup. Make sure to check back in for Part III where we will review various failure scenarios that could arise and the way the framework responds and recovers from these conditions.

What is MySQL Semisynchronous Replication?

Simply put, in a …

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