This section discusses a procedure for performing backups that enables you to recover data after several types of crashes:本节讨论了执行备份的过程，该过程使您能够在几种类型的崩溃后恢复数据：

The example commands do not include options such as --user and --password for the mysqldump and mysql client programs. 示例命令不包括mysqldump和mysql客户端程序的--user和--password等选项。You should include such options as necessary to enable client programs to connect to the MySQL server.您应该包含必要的选项，以使客户端程序能够连接到MySQL服务器。

Assume that data is stored in the InnoDB storage engine, which has support for transactions and automatic crash recovery. Assume also that the MySQL server is under load at the time of the crash. If it were not, no recovery would ever be needed.假设数据存储在InnoDB存储引擎中，该引擎支持事务和自动崩溃恢复。还假设MySQL服务器在崩溃时负载不足。如果没有，就永远不需要复苏。

For cases of operating system crashes or power failures, we can assume that MySQL's disk data is available after a restart. 对于操作系统崩溃或电源故障的情况，我们可以假设MySQL的磁盘数据在重启后可用。The InnoDB data files might not contain consistent data due to the crash, but InnoDB reads its logs and finds in them the list of pending committed and noncommitted transactions that have not been flushed to the data files. 由于崩溃，InnoDB数据文件可能不包含一致的数据，但InnoDB读取其日志，并在其中找到尚未刷新到数据文件的未决已提交和未提交事务的列表。InnoDB automatically rolls back those transactions that were not committed, and flushes to its data files those that were committed. InnoDB会自动回滚未提交的事务，并将已提交的事务刷新到其数据文件中。Information about this recovery process is conveyed to the user through the MySQL error log. The following is an example log excerpt:有关此恢复过程的信息通过MySQL错误日志传达给用户。以下是日志摘录示例：

InnoDB: Database was not shut down normally.
InnoDB: Starting recovery from log files...
InnoDB: Starting log scan based on checkpoint at
InnoDB: log sequence number 0 13674004
InnoDB: Doing recovery: scanned up to log sequence number 0 13739520
InnoDB: Doing recovery: scanned up to log sequence number 0 13805056
InnoDB: Doing recovery: scanned up to log sequence number 0 13870592
InnoDB: Doing recovery: scanned up to log sequence number 0 13936128
...
InnoDB: Doing recovery: scanned up to log sequence number 0 20555264
InnoDB: Doing recovery: scanned up to log sequence number 0 20620800
InnoDB: Doing recovery: scanned up to log sequence number 0 20664692
InnoDB: 1 uncommitted transaction(s) which must be rolled back
InnoDB: Starting rollback of uncommitted transactions
InnoDB: Rolling back trx no 16745
InnoDB: Rolling back of trx no 16745 completed
InnoDB: Rollback of uncommitted transactions completed
InnoDB: Starting an apply batch of log records to the database...
InnoDB: Apply batch completed
InnoDB: Started
mysqld: ready for connections

For the cases of file system crashes or hardware problems, we can assume that the MySQL disk data is not available after a restart. 对于文件系统崩溃或硬件问题的情况，我们可以假设MySQL磁盘数据在重启后不可用。This means that MySQL fails to start successfully because some blocks of disk data are no longer readable. In this case, it is necessary to reformat the disk, install a new one, or otherwise correct the underlying problem. 这意味着MySQL无法成功启动，因为某些磁盘数据块不再可读。在这种情况下，有必要重新格式化磁盘、安装新磁盘或以其他方式纠正潜在问题。Then it is necessary to recover our MySQL data from backups, which means that backups must already have been made. To make sure that is the case, design and implement a backup policy.然后，有必要从备份中恢复MySQL数据，这意味着必须已经进行了备份。为了确保这一点，设计并实施一个备份策略。