Redis配置文件

INCLUDES

################################## INCLUDES ###################################

# Include one or more other config files here.  This is useful if you
# have a standard template that goes to all Redis servers but also need
# to customize a few per-server settings.  Include files can include
# other files, so use this wisely.
#
# Note that option "include" won't be rewritten by command "CONFIG REWRITE"
# from admin or Redis Sentinel. Since Redis always uses the last processed
# line as value of a configuration directive, you'd better put includes
# at the beginning of this file to avoid overwriting config change at runtime.
#
# If instead you are interested in using includes to override configuration
# options, it is better to use include as the last line.
#
# include /path/to/local.conf
# include /path/to/other.conf

我们知道Redis只有一个配置文件,如果多个人进行开发维护,那么就需要多个这样的配置文件,这时候多个配置文件就可以在此通过 include /path/to/local.conf 配置进来,而原本的 redis.conf 配置文件就作为一个总闸,如果将此配置写在redis.conf 文件的开头,那么后面的配置会覆盖引入文件的配置,如果想以引入文件的配置为主,那么需要将 include 配置写在 redis.conf 文件的末尾。

MODULES

################################## MODULES #####################################

# Load modules at startup. If the server is not able to load modules
# it will abort. It is possible to use multiple loadmodule directives.
#
# loadmodule /path/to/my_module.so
# loadmodule /path/to/other_module.so

通过这里的 loadmodule 配置将引入自定义模块来新增一些功能。

NETWORK

################################## NETWORK #####################################

# By default, if no "bind" configuration directive is specified, Redis listens
# for connections from all available network interfaces on the host machine.
# It is possible to listen to just one or multiple selected interfaces using
# the "bind" configuration directive, followed by one or more IP addresses.
# Each address can be prefixed by "-", which means that redis will not fail to
# start if the address is not available. Being not available only refers to
# addresses that does not correspond to any network interfece. Addresses that
# are already in use will always fail, and unsupported protocols will always BE
# silently skipped.
bind 127.0.0.1 
protected-mode yes
port 6379
timeout 0
tcp-keepalive 300

1、bind:绑定redis服务器网卡IP,默认为127.0.0.1,即本地回环地址。如果未设置由于protected-mode=yes 依旧会使用本地回环地址

2、port:指定redis运行的端口,默认是6379。

3、timeout:设置客户端连接时的超时时间,单位为秒。当客户端在这段时间内没有发出任何指令,那么关闭该连接。默认值为0,表示不关闭。

4、tcp-keepalive :单位是秒,表示将周期性的使用SO_KEEPALIVE检测客户端是否还处于健康状态,避免服务器一直阻塞,官方给出的建议值是300s,如果设置为0,则不会周期性的检测。

GENERAL

################################# GENERAL #####################################

# By default Redis does not run as a daemon. Use 'yes' if you need it.
# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
# When Redis is supervised by upstart or systemd, this parameter has no impact.
daemonize no

# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
#   supervised no      - no supervision interaction
#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode
#                        requires "expect stop" in your upstart job config
#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
#                        on startup, and updating Redis status on a regular
#                        basis.

**1、daemonize:设置为yes表示指定Redis以守护进程的方式启动(后台启动)。默认值为 no

2、pidfile:配置PID文件路径,当redis作为守护进程运行的时候,它会把 pid 默认写到 /var/redis/run/redis_6379.pid 文件里面

3、loglevel :定义日志级别。默认值为notice,有如下4种取值:

debug(记录大量日志信息,适用于开发、测试阶段)

verbose(较多日志信息)

notice(适量日志信息,使用于生产环境)

warning(仅有部分重要、关键信息才会被记录)

4、logfile :配置log文件地址,默认打印在命令行终端的窗口上

5、databases:设置数据库的数目。默认的数据库是DB 0 ,可以在每个连接上使用select 命令选择一个不同的数据库,dbid是一个介于0到databases - 1 之间的数值。默认值是 16,也就是说默认Redis有16个数据库。**

SNAPSHOTTING

################################ SNAPSHOTTING  ################################

# Save the DB to disk.
#
# save  
#
# Redis will save the DB if both the given number of seconds and the given
# number of write operations against the DB occurred.
#
# Snapshotting can be completely disabled with a single empty string argument
# as in following example:
#
# save ""
#
# Unless specified otherwise, by default Redis will save the DB:
#   * After 3600 seconds (an hour) if at least 1 key changed
#   * After 300 seconds (5 minutes) if at least 100 keys changed
#   * After 60 seconds if at least 10000 keys changed
#
# You can set these explicitly by uncommenting the three following lines.
#
# save 3600 1
# save 300 100
# save 60 10000

1、save:这里是用来配置触发 Redis的持久化条件,也就是什么时候将内存中的数据保存到硬盘。

save 900 1:表示900 秒内如果至少有 1 个 key 的值变化,则保存
save 300 10:表示300 秒内如果至少有 10 个 key 的值变化,则保存
save 60 10000:表示60 秒内如果至少有 10000 个 key 的值变化,则保存

当然如果你只是用Redis的缓存功能,不需要持久化,那么你可以注释掉所有的 save 行来停用保存功能。可以直接一个空字符串来实现停用:save ""

2、stop-writes-on-bgsave-error :默认值为yes。当启用了RDB且最后一次后台保存数据失败,Redis是否停止接收数据。这会让用户意识到数据没有正确持久化到磁盘上,否则没有人会注意到灾难(disaster)发生了。如果Redis重启了,那么又可以重新开始接收数据了

3、rdbcompression ;默认值是yes。对于存储到磁盘中的快照,可以设置是否进行压缩存储。如果是的话,redis会采用LZF算法进行压缩。如果你不想消耗CPU来进行压缩的话,可以设置为关闭此功能,但是存储在磁盘上的快照会比较大。

4、rdbchecksum :默认值是yes。在存储快照后,我们还可以让redis使用CRC64算法来进行数据校验,如果希望获取到最大的性能提升,可以关闭此功能。

5、dbfilename :设置快照的文件名,默认是 dump.rdb

6、dir:设置快照文件的存放路径,这个配置项一定是个目录,而不能是文件名。使用上面的 dbfilename 作为保存的文件名。

REPLICATION

################################# REPLICATION #################################

# Master-Replica replication. Use replicaof to make a Redis instance a copy of
# another Redis server. A few things to understand ASAP about Redis replication.
#
#   +------------------+      +---------------+
#   |      Master      | ---> |    Replica    |
#   | (receive writes) |      |  (exact copy) |
#   +------------------+      +---------------+
#
# 1) Redis replication is asynchronous, but you can configure a master to
#    stop accepting writes if it appears to be not connected with at least
#    a given number of replicas.
# 2) Redis replicas are able to perform a partial resynchronization with the
#    master if the replication link is lost for a relatively small amount of
#    time. You may want to configure the replication backlog size (see the next
#    sections of this file) with a sensible value depending on your needs.
# 3) Replication is automatic and does not need user intervention. After a
#    network partition replicas automatically try to reconnect to masters
#    and resynchronize with them.
#
# replicaof  

# If the master is password protected (using the "requirepass" configuration
# directive below) it is possible to tell the replica to authenticate before
# starting the replication synchronization process, otherwise the master will
# refuse the replica request.
#
# masterauth 

①、slave-serve-stale-data:默认值为yes。当一个 slave 与 master 失去联系,或者复制正在进行的时候,slave 可能会有两种表现:

1) 如果为 yes ,slave 仍然会应答客户端请求,但返回的数据可能是过时,或者数据可能是空的在第一次同步的时候

2) 如果为 no ,在你执行除了 info he salveof 之外的其他命令时,slave 都将返回一个 "SYNC with master in progress" 的错误

②、slave-read-only:配置Redis的Slave实例是否接受写操作,即Slave是否为只读Redis。默认值为yes。

③、repl-diskless-sync:主从数据复制是否使用无硬盘复制功能。默认值为no。

④、repl-diskless-sync-delay:当启用无硬盘备份,服务器等待一段时间后才会通过套接字向从站传送RDB文件,这个等待时间是可配置的。 这一点很重要,因为一旦传送开始,就不可能再为一个新到达的从站服务。从站则要排队等待下一次RDB传送。因此服务器等待一段 时间以期更多的从站到达。延迟时间以秒为单位,默认为5秒。要关掉这一功能,只需将它设置为0秒,传送会立即启动。默认值为5。

⑤、repl-disable-tcp-nodelay:同步之后是否禁用从站上的TCP_NODELAY 如果你选择yes,redis会使用较少量的TCP包和带宽向从站发送数据。但这会导致在从站增加一点数据的延时。 Linux内核默认配置情况下最多40毫秒的延时。如果选择no,从站的数据延时不会那么多,但备份需要的带宽相对较多。默认情况下我们将潜在因素优化,但在高负载情况下或者在主从站都跳的情况下,把它切换为yes是个好主意。默认值为no。

MEMORY MANAGEMENT

############################## MEMORY MANAGEMENT ################################

# Set a memory usage limit to the specified amount of bytes.
# When the memory limit is reached Redis will try to remove keys
# according to the eviction policy selected (see maxmemory-policy).
#
# If Redis can't remove keys according to the policy, or if the policy is
# set to 'noeviction', Redis will start to reply with errors to commands
# that would use more memory, like SET, LPUSH, and so on, and will continue
# to reply to read-only commands like GET.
#
# This option is usually useful when using Redis as an LRU or LFU cache, or to
# set a hard memory limit for an instance (using the 'noeviction' policy).
#
# WARNING: If you have replicas attached to an instance with maxmemory on,
# the size of the output buffers needed to feed the replicas are subtracted
# from the used memory count, so that network problems / resyncs will
# not trigger a loop where keys are evicted, and in turn the output
# buffer of replicas is full with DELs of keys evicted triggering the deletion
# of more keys, and so forth until the database is completely emptied.
#
# In short... if you have replicas attached it is suggested that you set a lower
# limit for maxmemory so that there is some free RAM on the system for replica
# output buffers (but this is not needed if the policy is 'noeviction').

1、maxmemory:设置Redis的最大内存,如果设置为0 。表示不作限制。通常是配合下面介绍的maxmemory-policy参数一起使用。

2、maxmemory-policy :当内存使用达到maxmemory设置的最大值时,redis使用的内存清除策略。有以下几种可以选择:

1)volatile-lru 利用LRU算法移除设置过过期时间的key (LRU:最近使用 Least Recently Used )

2)allkeys-lru 利用LRU算法移除任何key

3)volatile-random 移除设置过过期时间的随机key

4)allkeys-random 移除随机key

5)volatile-ttl 移除即将过期的key(minor TTL)

6)noeviction noeviction 不移除任何key,只是返回一个写错误 ,默认选项

3、maxmemory-samples :LRU 和 minimal TTL 算法都不是精准的算法,但是相对精确的算法(为了节省内存)。随意你可以选择样本大小进行检,redis默认选择3个样本进行检测,你可以通过maxmemory-samples进行设置样本数。

APPEND ONLY MODE

############################## APPEND ONLY MODE ###############################

# By default Redis asynchronously dumps the dataset on disk. This mode is
# good enough in many applications, but an issue with the Redis process or
# a power outage may result into a few minutes of writes lost (depending on
# the configured save points).
#
# The Append Only File is an alternative persistence mode that provides
# much better durability. For instance using the default data fsync policy
# (see later in the config file) Redis can lose just one second of writes in a
# dramatic event like a server power outage, or a single write if something
# wrong with the Redis process itself happens, but the operating system is
# still running correctly.
#
# AOF and RDB persistence can be enabled at the same time without problems.
# If the AOF is enabled on startup Redis will load the AOF, that is the file
# with the better durability guarantees.
#
# Please check http://redis.io/topics/persistence for more information.

appendonly no

1、appendonly:默认redis使用的是rdb方式持久化,这种方式在许多应用中已经足够用了。但是redis如果中途宕机,会导致可能有几分钟的数据丢失,根据save来策略进行持久化,Append Only File是另一种持久化方式, 可以提供更好的持久化特性。Redis会把每次写入的数据在接收后都写入appendonly.aof文件,每次启动时Redis都会先把这个文件的数据读入内存里,先忽略RDB文件。默认值为no。

2、appendfilename :aof文件名,默认是"appendonly.aof"

3、appendfsync:aof持久化策略的配置;no表示不执行fsync,由操作系统保证数据同步到磁盘,速度最快;always表示每次写入都执行fsync,以保证数据同步到磁盘;everysec表示每秒执行一次fsync,可能会导致丢失这1s数据

4、no-appendfsync-on-rewrite:在aof重写或者写入rdb文件的时候,会执行大量IO,此时对于everysec和always的aof模式来说,执行fsync会造成阻塞过长时间,no-appendfsync-on-rewrite字段设置为默认设置为no。如果对延迟要求很高的应用,这个字段可以设置为yes,否则还是设置为no,这样对持久化特性来说这是更安全的选择。 设置为yes表示rewrite期间对新写操作不fsync,暂时存在内存中,等rewrite完成后再写入,默认为no,建议yes。Linux的默认fsync策略是30秒。可能丢失30秒数据。默认值为no。

5、auto-aof-rewrite-percentage:默认值为100。aof自动重写配置,当目前aof文件大小超过上一次重写的aof文件大小的百分之多少进行重写,即当aof文件增长到一定大小的时候,Redis能够调用bgrewriteaof对日志文件进行重写。当前AOF文件大小是上次日志重写得到AOF文件大小的二倍(设置为100)时,自动启动新的日志重写过程。

6、auto-aof-rewrite-min-size:64mb。设置允许重写的最小aof文件大小,避免了达到约定百分比但尺寸仍然很小的情况还要重写。

7、aof-load-truncated:aof文件可能在尾部是不完整的,当redis启动的时候,aof文件的数据被载入内存。重启可能发生在redis所在的主机操作系统宕机后,尤其在ext4文件系统没有加上data=ordered选项,出现这种现象 redis宕机或者异常终止不会造成尾部不完整现象,可以选择让redis退出,或者导入尽可能多的数据。如果选择的是yes,当截断的aof文件被导入的时候,会自动发布一个log给客户端然后load。如果是no,用户必须手动redis-check-aof修复AOF文件才可以。默认值为 yes。

REDIS CLUSTER

################################ REDIS CLUSTER  ###############################

# Normal Redis instances can't be part of a Redis Cluster; only nodes that are
# started as cluster nodes can. In order to start a Redis instance as a
# cluster node enable the cluster support uncommenting the following:
#
# cluster-enabled yes

# Every cluster node has a cluster configuration file. This file is not
# intended to be edited by hand. It is created and updated by Redis nodes.
# Every Redis Cluster node requires a different cluster configuration file.
# Make sure that instances running in the same system do not have
# overlapping cluster configuration file names.
#
# cluster-config-file nodes-6379.conf

1、cluster-enabled:集群开关,默认是不开启集群模式。

2、cluster-config-file:集群配置文件的名称,每个节点都有一个集群相关的配置文件,持久化保存集群的信息。 这个文件并不需要手动配置,这个配置文件有Redis生成并更新,每个Redis集群节点需要一个单独的配置文件。请确保与实例运行的系统中配置文件名称不冲突。默认配置为nodes-6379.conf。

3、cluster-node-timeout :可以配置值为15000。节点互连超时的阀值,集群节点超时毫秒数

4、cluster-slave-validity-factor :可以配置值为10。在进行故障转移的时候,全部slave都会请求申请为master,但是有些slave可能与master断开连接一段时间了, 导致数据过于陈旧,这样的slave不应该被提升为master。该参数就是用来判断slave节点与master断线的时间是否过长。判断方法是:比较slave断开连接的时间和(node-timeout * slave-validity-factor) + repl-ping-slave-period 如果节点超时时间为三十秒, 并且slave-validity-factor为10,假设默认的repl-ping-slave-period是10秒,即如果超过310秒slave将不会尝试进行故障转移

5、cluster-migration-barrier :可以配置值为1。master的slave数量大于该值,slave才能迁移到其他孤立master上,如这个参数若被设为2,那么只有当一个主节点拥有2 个可工作的从节点时,它的一个从节点会尝试迁移。

6、cluster-require-full-coverage:默认情况下,集群全部的slot有节点负责,集群状态才为ok,才能提供服务。 设置为no,可以在slot没有全部分配的时候提供服务。不建议打开该配置,这样会造成分区的时候,小分区的master一直在接受写请求,而造成很长时间数据不一致。

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