The best way to remove it from Mysql database relay logs, the safest way

Scenario
MySQL database master copy is automatically deleted from the default library in the relay logs after the SQL thread is finished. But: In relay_log_purge = 0 and MHA cluster it will not be automatically deleted need to be deleted manually. How safe to delete relay logs on the more critical!

There are two main ways:

One way:
to delete by MHA comes with the tool purge_relay_logs tool.

step:

1. Create a working directory

Objective To improve performance, the working directory must be on the same disk partition with mysql

mkdir -p /data/mha_tmp

2. purge relay logs

/usr/bin/purge_relay_logs --user=USERNAME --password=PASSWORD --host=Mysql_IP --disable_relay_log_purge --workdir=/data/mha_tmp 2>&1  

3. Added to the crontab

0 4 * * * /usr/bin/purge_relay_logs --user=USERNAME --password=PASSWORD --host=Mysql_IP --disable_relay_log_purge --workdir=/data/mha_tmp 2>&1

Description:
-disable_relay_log_purge: Auto Set "relay_log_purge = 1"

Second way:
Manually delete the relay log

1. Provided relay_log_purge = 1

SET GLOBAL relay_log_purge = 1

2. flush logs
   log in through the Administrator user from the database, and then execute the following command:

flush logs;

You can perform multiple!
Note :
if the observed accumulation of relay logs logs have been deleted, if deleted, the direct implementation of the following Step 6 "recovery relay_log_purge = 0"; if not removed, continue to "stop slave" from below step 3 down operation! ! !

3. Stop slave
   landed from the database by an administrator user, and then execute the following command:

stop slave;

4. Delete relay logs
   can be deleted directly by rm relay logs
   through the use of secure delete the following way:

The total number (1) All documents on the relay's statistics (including relay_log_name.index)

ls -A1 |grep relay | sort -rn | wc -l

(2) 列出要删除所有有关relay的文件：

ls -A1 |grep relay | sort -rn | tail -n 100

说明： 100 为要删除的relay logs 数量

(3) 确定没有问题，删除relay logs：

ls -A1 |grep relay | sort -rn | tail -n 100 | xargs rm -rf {}

注意：
要保留最新的两个relay log
要保留relay log的index文件
relay log的index一般命名为： relay_log_name.index
例如： relay-bin.index
5. 启动slave
通过管理员用户登陆从数据库，然后执行下面命令：

start slave;

6 . 恢复relay_log_purge = 0
通过管理员用户登陆从数据库，然后执行下面命令：

SET GLOBAL relay_log_purge=0;

扩展
如果你对从数据库要求不高，可以将relay_log_purge = 1