一、UNIT-单位

 # 1k => 1000 bytes
 # 1kb => 1024 bytes
 # 1m => 1000000 bytes
 # 1mb => 1024*1024 bytes
 # 1g => 1000000000 bytes
 # 1gb => 1024*1024*1024 bytes
 #
 # units are case insensitive so 1GB 1Gb 1gB are all the same.

注：

1. 配置文件开头定义了一些基本的度量单位，只支持bytes，不支持bit
2. 单位对大小写不敏感

二、INCLUDES-包含

包含拆分后的配置文件，方便维护

三、GENERAL-通用

1. 后台进程开关，默认为false

    # 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.
     daemonize yes
   

2. 后台运行时，将Redis进程id写入文件，其路径

    # When running daemonized, Redis writes a pid file in /var/run/redis.pid by
    # default. You can specify a custom pid file location here.
     pidfile /var/run/redis.pid
   

3. 端口占用

    # Accept connections on the specified port, default is 6379.
    # If port 0 is specified Redis will not listen on a TCP socket.
    port 6379
   

4. Tcp-backlog
   backlog是一个连接队列，backlog队列总和=未完成三次握手队列 + 已经完成三次握手队列

    # TCP listen() backlog.
    #
    # In high requests-per-second environments you need an high backlog in order
    # to avoid slow clients connections issues. Note that the Linux kernel
    # will silently truncate it to the value of /proc/sys/net/core/somaxconn so
    # make sure to raise both the value of somaxconn and tcp_max_syn_backlog
    # in order to get the desired effect.
    tcp-backlog 511
   

5. 监听来自哪些网卡的连接

    # By default Redis listens for connections from all the network interfaces
    # available on the server. It is possible to listen to just one or multiple
    # interfaces using the "bind" configuration directive, followed by one or
    # more IP addresses.
    #
    # Examples:
    #
    # bind 192.168.1.100 10.0.0.1
    # bind 127.0.0.1
   

6. 最大空闲时间

   # Close the connection after a client is idle for N seconds (0 to disable)
   timeout 0
   

7. 存活检测间隔，常用于集群

   # TCP keepalive.
   #
   # If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
   # of communication. This is useful for two reasons:
   #
   # 1) Detect dead peers.
   # 2) Take the connection alive from the point of view of network equipment in the middle.
   #
   # On Linux, the specified value (in seconds) is the period used to send ACKs  
   #
   # A reasonable value for this option is 60 seconds.
   tcp-keepalive 0
   

   注：
   (1) 单位为秒，建议设置为60
   (2) 若设置为0，则不会进行检测

8. 日志级别及日志文件名

    # Specify the server verbosity level.
    # This can be one of:
    # debug (a lot of information, useful for development/testing)
    # verbose (many rarely useful info, but not a mess like the debug level)
    # notice (moderately verbose, what you want in production probably)
    # warning (only very important / critical messages are logged)
    loglevel notice
   
    # Specify the log file name. Also the empty string can be used to force
    # Redis to log on the standard output. Note that if you use standard
    # output for logging but daemonize, logs will be sent to /dev/null
    logfile ""
   

9. Redis日志与系统日志syslog

   #是否把日志输出到syslog
    # To enable logging to the system logger, just set 'syslog-enabled' to yes,
    # and optionally update the other syslog parameters to suit your needs.
    # syslog-enabled no
   
    #指定syslog中的日志标识
    # Specify the syslog identity.
    # syslog-ident redis
   
   #指定syslog设备
    # Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
    # syslog-facility local0
   

10. 数据库数量

     # Set the number of databases. The default database is DB 0, you can select
     # a different one on a per-connection basis using SELECT <dbid> where
     # dbid is a number between 0 and 'databases'-1
     databases 16
    

四、SNAPSHOTTING-快照

1. 一次自动持久化的触发条件及禁用

   ################################ 	SNAPSHOTTING  	################################
   #
   # Save the DB on disk:
   #
   #   save <seconds> <changes>
   #
   #   Will save the DB if both the given number of seconds and the given
   #   number of write operations against the DB occurred.
   #
   #   In the example below the behaviour will be to save:
   #   after 900 sec (15 min) if at least 1 key changed
   #   after 300 sec (5 min) if at least 10 keys changed
   #   after 60 sec if at least 10000 keys changed
   #
   #   Note: you can disable saving completely by commenting out all "save" lines.
   #
   #   It is also possible to remove all the previously configured save
   #   points by adding a save directive with a single empty string argument
   #   like in the following example:
   #
   #   save ""
   
   save 900 1
   save 300 10
   save 60 10000
   

   注：默认三个条件
   (1) 15分钟内 900次更改
   (2) 5分钟内 10次更改
   (3) 1分钟内 10000次更改

2. 生成/读取持久化文件.rdb的文件名，默认为dump

   # The filename where to dump the DB
   dbfilename dump.rdb
   

3. 过程文件保存路径(.rdb .aof)

   # The working directory.
   #
   # The DB will be written inside this directory, with the filename specified
   # above using the 'dbfilename' configuration directive.
   #
   # The Append Only File will also be created inside this directory.
   #
   # Note that you must specify a directory here, not a file name.
   dir ./
   

   注：在redis-cli中执行CONFIG GET dir 会获取该值

4. 持久化文件.rdb生成错误时是否停止写操作

   # By default Redis will stop accepting writes if RDB snapshots are enabled
   # (at least one save point) and the latest background save failed.
   # This will make the user aware (in a hard way) that data is not persisting
   # on disk properly, otherwise chances are that no one will notice and some
   # disaster will happen.
   #
    # If the background saving process will start working again Redis will
   # automatically allow writes again.
   #
   # However if you have setup your proper monitoring of the Redis server
   # and persistence, you may want to disable this feature so that Redis will
   # continue to work as usual even if there are problems with disk,
   # permissions, and so forth.
   stop-writes-on-bgsave-error yes
   

   注：如果配置为no，表示不在乎数据一致性或有其他手段发现控制

5. 持久化文件.rdb压缩(LZF压缩算法)

   # Compress string objects using LZF when dump .rdb databases?
   # For default that's set to 'yes' as it's almost always a win.
   # If you want to save some CPU in the saving child set it to 'no' but
   # the dataset will likely be bigger if you have compressible values or keys.
   rdbcompression yes
   

6. 持久化文件.rdb校验(CRC64算法)

    # Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
   # This makes the format more resistant to corruption but there is a performance
   # hit to pay (around 10%) when saving and loading RDB files, so you can disable it
   # for maximum performances.
   #
   # RDB files created with checksum disabled have a checksum of zero that will
   # tell the loading code to skip the check.
   rdbchecksum yes
   

五、REPLICATION-复制

六、SECURITY-安全

1. 基于Linux安全加固环境，默认免密
2. 在redis-cli中执行：
   CONFIG GET requirepass，查看口令
   CONFIG SET requirepass，设置口令
   设置口令后，在操作之前必须AUTH {已设置的口令} 才可以进行操作

    # Require clients to issue AUTH <PASSWORD> before processing any other
    #commands.  This might be useful in environments in which you do not trust
    # others with access to the host running redis-server.
    #
    # This should stay commented out for backward compatibility and because most
    # people do not need auth (e.g. they run their own servers).
    #
    # Warning: since Redis is pretty fast an outside user can try up to
    # 150k passwords per second against a good box. This means that you should
    # use a very strong password otherwise it will be very easy to break.
    #
    # requirepass foobared
   

3. 重命名命令

   # Command renaming.
   #
   # It is possible to change the name of dangerous commands in a shared
   # environment. For instance the CONFIG command may be renamed into something
   # hard to guess so that it will still be available for internal-use tools
   # but not available for general clients.
   #
   # Example:
   #
   # rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
   #
   # It is also possible to completely kill a command by renaming it into
   #	an empty string:
   #
   # rename-command CONFIG ""
   

七、LIMIT-限制

1. 同时最大连接数，默认为10000

   # Set the max number of connected clients at the same time. By default
   # this limit is set to 10000 clients, however if the Redis server is not
   # able to configure the process file limit to allow for the specified limit
   # the max number of allowed clients is set to the current file limit
   # minus 32 (as Redis reserves a few file descriptors for internal uses).
   #
   # Once the limit is reached Redis will close all the new connections sending
   # an error 'max number of clients reached'.
   #
   # maxclients 10000
   

2. 最大可使用内存

   # Don't use more memory than 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 cache, or to set
   # a hard memory limit for an instance (using the 'noeviction' policy).
   #
   # WARNING: If you have slaves attached to an instance with maxmemory on,
   # the size of the output buffers needed to feed the slaves 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 slaves 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 slaves attached it is suggested that you set a lower
   # limit for maxmemory so that there is some free RAM on the system for slave
   # output buffers (but this is not needed if the policy is 'noeviction').
   # maxmemory <bytes>
   

3. 内存使用达到最大值后，启用清理策略

   # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
   # is reached. You can select among five behaviors:
   #
   # volatile-lru -> remove the key with an expire set using an LRU algorithm
   # allkeys-lru -> remove any key according to the LRU algorithm
   # volatile-random -> remove a random key with an expire set
   # allkeys-random -> remove a random key, any key
   # volatile-ttl -> remove the key with the nearest expire time (minor TTL)
   # noeviction -> don't expire at all, just return an error on write operations
   #
   # Note: with any of the above policies, Redis will return an error on write
   #       operations, when there are no suitable keys for eviction.
   #
   #       At the date of writing these commands are: set setnx setex append
   #       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd
   #       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby
   #       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby
   #       getset mset msetnx exec sort
   #
   # The default is:
   #
   # maxmemory-policy noeviction
   

4. 策略估算样本规模

    # LRU and minimal TTL algorithms are not precise algorithms but approximated
    # algorithms (in order to save memory), so you can tune it for speed or
    # accuracy. For default Redis will check five keys and pick the one that was
    # used less recently, you can change the sample size using the following
    # configuration directive.
    #
    # The default of 5 produces good enough results. 10 Approximates very closely
    # true LRU but costs a bit more CPU. 3 is very fast but not very accurate.
    #
    # maxmemory-samples 5
   

八、APPEND ONLY MODE-追加模型

1. append only开关，默认关闭

   ############################## 	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
   

2. 生成/读取AOF持久化文件.aof的文件名，默认为appendonly

   # The name of the append only file (default: "appendonly.aof")
   appendfilename "appendonly.aof"
   

3. 记录追加的触发条件及关闭

   # The fsync() call tells the Operating System to actually write data on disk
   # instead of waiting for more data in the output buffer. Some OS will really flush
   # data on disk, some other OS will just try to do it ASAP.
   #
   # Redis supports three different modes:
   #
   # no: don't fsync, just let the OS flush the data when it wants. Faster.
   # always: fsync after every write to the append only log. Slow, Safest.
   # everysec: fsync only one time every second. Compromise.
   #
   # The default is "everysec", as that's usually the right compromise between
   # speed and data safety. It's up to you to understand if you can relax this to
   # "no" that will let the operating system flush the output buffer when
   # it wants, for better performances (but if you can live with the idea of
   # some data loss consider the default persistence mode that's snapshotting),
   # or on the contrary, use "always" that's very slow but a bit safer than
   # everysec.
   #
   # More details please check the following article:
   # http://antirez.com/post/redis-persistence-demystified.html
   #
   # If unsure, use "everysec".
   
   # appendfsync always
   appendfsync everysec
   # appendfsync no
   

   注：
   -always，每次发生数据变更会被立即追加到磁盘上，性能较差但数据完整性比较好
   -everysec，出厂默认推荐，异步操作，每秒记录，若一秒内宕机，则这一秒数据丢失
   -no，不同步

4. 重写时是否追加记录，采用默认值no即可，保证数据安全。

    # When the AOF fsync policy is set to always or everysec, and a background
   # saving process (a background save or AOF log background rewriting) is
   # performing a lot of I/O against the disk, in some Linux configurations
   # Redis may block too long on the fsync() call. Note that there is no fix for
   # this currently, as even performing fsync in a different thread will block
   # our synchronous write(2) call.
   #
   # In order to mitigate this problem it's possible to use the following option
   # that will prevent fsync() from being called in the main process while a
   # BGSAVE or BGREWRITEAOF is in progress.
   #
   # This means that while another child is saving, the durability of Redis is
   # the same as "appendfsync none". In practical terms, this means that it is
   # possible to lose up to 30 seconds of log in the worst scenario (with the
   # default Linux settings).
   #
   # If you have latency problems turn this to "yes". Otherwise leave it as
   # "no" that is the safest pick from the point of view of durability.
   
   no-appendfsync-on-rewrite no
   

5. 自动重写触发条件

    # Automatic rewrite of the append only file.
   # Redis is able to automatically rewrite the log file implicitly calling
   # BGREWRITEAOF when the AOF log size grows by the specified percentage.
   #
   # This is how it works: Redis remembers the size of the AOF file after the
   # latest rewrite (if no rewrite has happened since the restart, the size of
   # the AOF at startup is used).
   #
   # This base size is compared to the current size. If the current size is
   # bigger than the specified percentage, the rewrite is triggered. Also
   # you need to specify a minimal size for the AOF file to be rewritten, this
   # is useful to avoid rewriting the AOF file even if the percentage increase
   # is reached but it is still pretty small.
   #
   # Specify a percentage of zero in order to disable the automatic AOF
   # rewrite feature.
   
   auto-aof-rewrite-percentage 100
   auto-aof-rewrite-min-size 64mb