Nginx反向代理负载均衡配置实战

1. mysqldump locks all myisam tables
2.If backup innodb, we can use "mysqldump --single-transaction"(if big table, add --quick) and will no locks

--single-transaction

This option sets the transaction isolation mode to

REPEATABLE READ

and sends a

START TRANSACTION

SQL statement to the server before dumping data. It is useful only with transactional tables such as

InnoDB

, because then it dumps the consistent state of the database at the time when

START TRANSACTION

was issued without blocking any applications.When using this option, you should keep in mind that only

InnoDB

tables are dumped in a consistent state. For example, any

MyISAM

or

MEMORY

tables dumped while using this option may still change state.While a

--single-transaction

dump is in process, to ensure a valid dump file (correct table contents and binary log coordinates), no other connection should use the following statements:

ALTER TABLE

,

CREATE TABLE

,

DROP TABLE

,

RENAME TABLE

,

TRUNCATE TABLE

. A consistent read is not isolated from those statements, so use of them on a table to be dumped can cause the

SELECT

that is performed by mysqldump to retrieve the table contents to obtain incorrect contents or fail.The

--single-transaction

option and the

--lock-tables

option are mutually exclusive because

LOCK TABLES

causes any pending transactions to be committed implicitly.This option is not supported for MySQL Cluster tables; the results cannot be guaranteed to be consistent due to the fact that the

NDBCLUSTER

storage engine supports only the

READ_COMMITTED

transaction isolation level. You should always use

NDB

backup and restore instead.To dump large tables, you should combine the

--single-transaction

option with

--quick

.3.Also if we switch to xtrabackup, http://www.percona.com/doc/percona-xtrabackup/2.1/, we can backup the binaries which doesn't lock innodb and backs up the binary. The benefit is you can create incremental backups after the main backup and it takes less then a few minutes to restore a backup