Redis4.0从库复制报错"master_link_status:down"处理一例

环境描述:

Redis版本:4.0.2

主库：192.168.0.190

从库：192.168.0.191

今天Zabbix告警一直出现redis sync error的信息，于是登陆redis发现从库复制状态一直是master_link_status:down的状态。

从库日志报错信息如下：

17365:S 28 Dec 14:45:15.294 * Connecting to MASTER 192.168.0.190:6379

17365:S 28 Dec 14:45:15.294 * MASTER <-> SLAVE sync started

17365:S 28 Dec 14:45:15.294 * Non blocking connect for SYNC fired the event.

17365:S 28 Dec 14:45:15.295 * Master replied to PING, replication can continue...

17365:S 28 Dec 14:45:15.295 * Partial resynchronization not possible (no cached master)

17365:S 28 Dec 14:45:15.341 * Full resync from master: 3987160bba8279fe30b828fb339d1c0c6536a3ab:182474982617073

17365:S 28 Dec 14:45:17.293 # I/O error reading bulk count from MASTER: Resource temporarily unavailable

主库报错日志信息如下：

25573:M 28 Dec 15:38:53.255 * Background saving started by pid 12067

25573:M 28 Dec 15:38:53.258 # Client id=87019085 addr=192.168.0.191:1440 fd=110 name= age=0 idle=0 flags=S db=0 sub=0 psub=0 multi=-1 qbuf=0 qbuf-free=0 obl=6641 oll=1 omem=19125 events=r cmd=psync scheduled to be closed ASAP for overcoming of output buffer limits.

25573:M 28 Dec 15:38:53.356 # Connection with slave 192.168.0.191:6379 lost.

从主库日志中我们可以看出在redis主库在接到从库要求重新同步数据的时候先生成一个rdb文件，再通过psync来做部分同步，可以看到问题就出在这一块，

持续报错”psync scheduled to be closed ASAP“，这个原因是由于client-output-buffer-limit值设置的太小从而导致数据发送失败。

解决方法:

登陆主库和从库修改缓冲区占用内容大小限制：

127.0.0.1:6379> config set client-output-buffer-limit "slave 8589934592 2147483648 0"

OK

同步到配置文件:

127.0.0.1:6379> config rewrite

OK

查看配置文件内容

# cat redis.conf |grep client-output-buffer-limit  

client-output-buffer-limit normal 0 0 0

client-output-buffer-limit slave 8gb 2gb 0

登陆从库192.168.0.191,再次观察主从复制状态，发现从库的的复制状态很快就变成了up：

# redis-cli info replication

# Replication

role:slave

master_host:192.168.0.190

master_port:6379

master_link_status:up

至此，问题处理完毕。

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转载于:http://blog.itpub.net/15498/viewspace-2286846/