With a value of 2, only an operating system crash or a power outage can erase the last second of transactions. The log buffer is written out to the file at each commit, but the flush to disk operation is not performed on it. Before MySQL 5.6.6, the flushing on the log file takes place once per second. Note that the once-per-second flushing is not 100% guaranteed to happen every second, due to process scheduling issues. As of MySQL 5.6.6, flushing frequency is controlled by innodb_flush_log_at_timeout instead.( 操作 系统 crash或电源故障导致丢失最后一秒的事务)
InnoDB's crash recovery works regardless of the value. Transactions are either applied entirely or erased entirely.(Innodb存储引擎存与该参数无关，可以通过crash recovery来解决，要么提交，要么回滚)
For the greatest possible durability and consistency in a replication setup using InnoDB with transactions, use innodb_flush_log_at_trx_commit =1 and sync_binlog=1 in your master server my.cnf file.
3、参数sync_binlog
sync_binlog为全局动态参数，取值范围为0 .. 18446744073709547520，缺省值为0。
If the value of this variable is greater than 0, the MySQL server synchronizes its binary log to disk (using fdatasync()) after every sync_binlog writes to the binary log. There is one write to the binary log per statement if autocommit is enabled, and one write per transaction otherwise.
The default value of sync_binlog is 0, which does no synchronizing to disk. A value of 1 is the safest choice, because in the event of a crash you lose at most one statement or transaction from the binary log. However, it is also the slowest choice (unless the disk has a battery-backed cache, which makes synchronization very fast).
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