Redis3.0 Cluster Redis集群搭建

一、介绍

Redis 集群是一个提供在多个Redis间节点间共享数据的程序集.redis3.0以前，只支持主从同步的，如果主的挂了，写入就成问题了。而官方的Redis Cluster出来后就可以很好帮我们解决这个问题；可以做到节点的自动发现、集群容错slave->master、人为操纵分片(slots)等等

Redis Cluster 架构

• 架构细节：

  (1)、所有的redis节点彼此互联(PING-PONG机制),内部使用二进制协议优化传输速度和带宽.

  (2)、节点的fail是通过集群中超过半数的节点检测失效时才生效.

  (3)、客户端与redis节点直连,不需要中间proxy层.客户端不需要连接集群所有节点,连接集群中任何一个可用节点即可

  (4)、redis-cluster把所有的物理节点映射到[0-16383]slot上,cluster负责维护node<->slot<->value

Redis Cluster选举容错架构

• 
  

  架构细节:

  (1)、容错选举过程是集群中所有master参与,如果半数以上master节点与master节点通信超过(cluster-node-timeout),认为当前master节点挂掉.

  (2)、什么时候整个集群不可用(cluster_state:fail),当集群不可用时,所有对集群的操作做都不可用，收到((error) CLUSTERDOWN The cluster is down)错误

      a:如果集群任意master挂掉,且当前master没有slave.集群进入fail状态,也可以理解成进群的slot映射[0-16383]不完成时进入fail状态.

      b:如果进群超过半数以上master挂掉，无论是否有slave集群进入fail状态.

二、准备

1. 三台虚拟机地址：192.168.240.139、192.168.240.140、192.168.240.141
2. 在Linux（CentOS 7）上安装Redis：Windows安装Linux虚拟机（CentOS7）
3. Redis版本：redis-3.2.1.tar.gz或者http://download.redis.io/releases/redis-3.2.1.tar.gz

三、思路

三台虚拟机，每台启动一主一从，总共6个redis-cluster集群；每台机器的master端口为6379，slave端口为6380.

四、搭建

1. 在redis安装目录下进入utils目录：/usr/local/redis-3.2.1/utils
   
   
2. 启动install_server.sh：

   ./install_server.sh

   
   
   
3. 此时会出现对Redis一些参数的初始化操作，下图[]中的参数代表默认值，使用默认值直接点击回车，自己设定直接输入后回车：端口号、配置文件、日志文件、实例安装目录、执行路径（注意：需要指定为自己redis的安装目录的执行路径，如：/usr/local/redis-3.2.1/src/redis-server）；此时会有配置信息列表，没有问题点击ENTER确认。
   
   
4. 执行1-3步，就已经将master6379的配置信息创建好了，重复1-3，但是在一开始端口输入时输入6380，如下图完成slave6380的配置信息创建。
   
   
5. 切换到目录：/etc/redis/下，我们会看到刚才配置的6379.conf和6380.conf。因为我们是集群，需要对配置文件做修改来满足集群的要求。这边我只说我修改了什么，具体我这边的完整配置在问题解决中贴出。

   #注释掉本地IP绑定或者改为bind 0.0.0.0，强烈建议改为0.0.0.0
   bind 0.0.0.0
   #保护模式改为no，否则除非你设置密码，不然的话远程客户端是无法连接使用的
   protected-mode no
   #master为6379时不用修改，否则需要改成对应端口，如6380
   port 6379
   # 默认情况下 redis 不是作为守护进程运行的，如果你想让它在后台运行，你就把它改成 yes。  
   # 当redis作为守护进程运行的时候，它会写一个 pid 到 /var/run/redis.pid 文件里面。
   daemonize yes
   #非6379时需要修改
   logfile /var/log/redis_6379.log
   #非6379时需要修改
   dir /var/lib/redis/6379
   #开启集群支持
   cluster-enabled yes
   #非6379时需要修改
   cluster-config-file nodes-6379.conf
   #设置超时时间
   cluster-node-timeout 5000

   
   

   #注释掉本地IP绑定或者改为bind 0.0.0.0，强烈建议改为0.0.0.0
   bind 0.0.0.0
   #保护模式改为no，否则除非你设置密码，不然的话远程客户端是无法连接使用的
   protected-mode no
   #master为6379时不用修改，否则需要改成对应端口，如6380（自动）
   port 6380
   # 默认情况下 redis 不是作为守护进程运行的，如果你想让它在后台运行，你就把它改成 yes。  
   # 当redis作为守护进程运行的时候，它会写一个 pid 到 /var/run/redis.pid 文件里面。
   daemonize yes
   #非6379时需要修改（自动）
   logfile /var/log/redis_6379.log
   #非6379时需要修改（自动）
   dir /var/lib/redis/6379
   #开启集群支持
   cluster-enabled yes
   #非6379时需要修改（手动）
   cluster-config-file nodes-6380.conf
   #设置超时时间
   cluster-node-timeout 5000

   
   
6. 在另外两台机器上同样执行第5步进行配置。
   
   
7. 分别启动着六台redis：

   /etc/init.d/redis_6379 restart
   /etc/init.d/redis_6380 restart

   
   
   
8. 启动redis集群，只需要在某个一台上启动即可：src目录下：/usr/local/redis-3.2.1/src

   ./redis-trib.rb create --replicas 1 192.168.240.139:6379 192.168.240.139:6380 192.168.240.140:6379 192.168.240.140:6380 192.168.240.141:6379 192.168.240.141:6380

   
   
   
9. 如果没有任何问题，会正常启动,记得需要确认下集群配置。有问题请看第五点：解决问题！
   
   

五、测试

在192.168.240.139（以下简称139）和192.168.240.140（以下简称140）上分别开启客户端，在139存入gbj=孤天浪雨，在140取得gbj的值；注意：以集群模式启动，所以要加上-c:

./redis-cli -c

查看集群节点信息：redis-trib.rb check 127.0.0.1:6379

六、解决问题

1. 执行集群启动命令时：我这边报错是：/usr/bin/env: ruby: 没有那个文件或目录；其实只要是报有关ruby问题，都有可能是没有安装ruby：
   
   解决：安装ruby
   

   yum install ruby

   
   
   
   

2. 没有使用gem安装redis ruby接口：

   解决：  安装redis ruby接口，有时比较慢，耐心等待！！！
   

   gem install redis

   
   
   
   
3. [ERR] Sorry, can't connect to node 192.168.240.139:6379：网上说是因为ruby版本太低。解决1：更新ruby、重新安装redis ruby接口
   

   gem update --system
   gem install redis

   1. 解决2：检查上面的.conf配置，bind 127.0.0.1建议改为bind 0.0.0.0；你可能是注释掉了！
   
   
   
4. redis单个启动时：Could not connect to Redis at 127.0.0.1:6379: Connection refused解决：将/var/run/redis_6379.pid文件删除
   
   
5. 6380.conf文件中的详细配置可以参考这边：redis配置详解

   ## Generated by install_server.sh ##
   # Redis configuration file example.
   #
   # Note that in order to read the configuration file, Redis must be
   # started with the file path as first argument:
   #
   # ./redis-server /path/to/redis.conf
   
   # Note on units: when memory size is needed, it is possible to specify
   # it in the usual form of 1k 5GB 4M and so forth:
   #
   # 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.
   
   ################################## 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.
   #
   # Notice 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
   
   ################################## NETWORK #####################################
   
   # By default, if no "bind" configuration directive is specified, Redis listens
   # for connections from all the network interfaces available on the server.
   # It is possible to listen to just one or multiple selected 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 ::1
   #
   # ~~~ WARNING ~~~ If the computer running Redis is directly exposed to the
   # internet, binding to all the interfaces is dangerous and will expose the
   # instance to everybody on the internet. So by default we uncomment the
   # following bind directive, that will force Redis to listen only into
   # the IPv4 lookback interface address (this means Redis will be able to
   # accept connections only from clients running into the same computer it
   # is running).
   #
   # IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
   # JUST COMMENT THE FOLLOWING LINE.
   # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   bind 0.0.0.0
   
   # Protected mode is a layer of security protection, in order to avoid that
   # Redis instances left open on the internet are accessed and exploited.
   #
   # When protected mode is on and if:
   #
   # 1) The server is not binding explicitly to a set of addresses using the
   #    "bind" directive.
   # 2) No password is configured.
   #
   # The server only accepts connections from clients connecting from the
   # IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain
   # sockets.
   #
   # By default protected mode is enabled. You should disable it only if
   # you are sure you want clients from other hosts to connect to Redis
   # even if no authentication is configured, nor a specific set of interfaces
   # are explicitly listed using the "bind" directive.
   protected-mode no
   
   # Accept connections on the specified port, default is 6379 (IANA #815344).
   # If port 0 is specified Redis will not listen on a TCP socket.
   port 6380
   
   # 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
   
   # Unix socket.
   #
   # Specify the path for the Unix socket that will be used to listen for
   # incoming connections. There is no default, so Redis will not listen
   # on a unix socket when not specified.
   #
   # unixsocket /tmp/redis.sock
   # unixsocketperm 700
   
   # Close the connection after a client is idle for N seconds (0 to disable)
   timeout 0
   
   # 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.
   # Note that to close the connection the double of the time is needed.
   # On other kernels the period depends on the kernel configuration.
   #
   # A reasonable value for this option is 300 seconds, which is the new
   # Redis default starting with Redis 3.2.1.
   tcp-keepalive 300
   
   ################################# 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.
   daemonize yes
   
   # 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
   #   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
   #   supervised auto    - detect upstart or systemd method based on
   #                        UPSTART_JOB or NOTIFY_SOCKET environment variables
   # Note: these supervision methods only signal "process is ready."
   #       They do not enable continuous liveness pings back to your supervisor.
   supervised no
   
   # If a pid file is specified, Redis writes it where specified at startup
   # and removes it at exit.
   #
   # When the server runs non daemonized, no pid file is created if none is
   # specified in the configuration. When the server is daemonized, the pid file
   # is used even if not specified, defaulting to "/var/run/redis.pid".
   #
   # Creating a pid file is best effort: if Redis is not able to create it
   # nothing bad happens, the server will start and run normally.
   pidfile /var/run/redis_6380.pid
   
   # 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 /var/log/redis_6380.log
   
   # 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
   
   # Specify the syslog identity.
   # syslog-ident redis
   
   # Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
   # syslog-facility local0
   
   # Set the number of databases. The default database is DB 0, you can select
   # a different one on a per-connection basis using SELECT  where
   # dbid is a number between 0 and 'databases'-1
   databases 16
   
   ################################ SNAPSHOTTING  ################################
   #
   # Save the DB on disk:
   #
   #   save  
   #
   #   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
   
   # 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
   
   # 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
   
   # 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
   
   # The filename where to dump the DB
   dbfilename dump.rdb
   
   # 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 /var/lib/redis/6380
   
   ################################# REPLICATION #################################
   
   # Master-Slave replication. Use slaveof to make a Redis instance a copy of
   # another Redis server. A few things to understand ASAP about Redis replication.
   #
   # 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 slaves.
   # 2) Redis slaves 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 slaves automatically try to reconnect to masters
   #    and resynchronize with them.
   #
   # slaveof  
   
   # If the master is password protected (using the "requirepass" configuration
   # directive below) it is possible to tell the slave to authenticate before
   # starting the replication synchronization process, otherwise the master will
   # refuse the slave request.
   #
   # masterauth 
   
   # When a slave loses its connection with the master, or when the replication
   # is still in progress, the slave can act in two different ways:
   #
   # 1) if slave-serve-stale-data is set to 'yes' (the default) the slave will
   #    still reply to client requests, possibly with out of date data, or the
   #    data set may just be empty if this is the first synchronization.
   #
   # 2) if slave-serve-stale-data is set to 'no' the slave will reply with
   #    an error "SYNC with master in progress" to all the kind of commands
   #    but to INFO and SLAVEOF.
   #
   slave-serve-stale-data yes
   
   # You can configure a slave instance to accept writes or not. Writing against
   # a slave instance may be useful to store some ephemeral data (because data
   # written on a slave will be easily deleted after resync with the master) but
   # may also cause problems if clients are writing to it because of a
   # misconfiguration.
   #
   # Since Redis 2.6 by default slaves are read-only.
   #
   # Note: read only slaves are not designed to be exposed to untrusted clients
   # on the internet. It's just a protection layer against misuse of the instance.
   # Still a read only slave exports by default all the administrative commands
   # such as CONFIG, DEBUG, and so forth. To a limited extent you can improve
   # security of read only slaves using 'rename-command' to shadow all the
   # administrative / dangerous commands.
   slave-read-only yes
   
   # Replication SYNC strategy: disk or socket.
   #
   # -------------------------------------------------------
   # WARNING: DISKLESS REPLICATION IS EXPERIMENTAL CURRENTLY
   # -------------------------------------------------------
   #
   # New slaves and reconnecting slaves that are not able to continue the replication
   # process just receiving differences, need to do what is called a "full
   # synchronization". An RDB file is transmitted from the master to the slaves.
   # The transmission can happen in two different ways:
   #
   # 1) Disk-backed: The Redis master creates a new process that writes the RDB
   #                 file on disk. Later the file is transferred by the parent
   #                 process to the slaves incrementally.
   # 2) Diskless: The Redis master creates a new process that directly writes the
   #              RDB file to slave sockets, without touching the disk at all.
   #
   # With disk-backed replication, while the RDB file is generated, more slaves
   # can be queued and served with the RDB file as soon as the current child producing
   # the RDB file finishes its work. With diskless replication instead once
   # the transfer starts, new slaves arriving will be queued and a new transfer
   # will start when the current one terminates.
   #
   # When diskless replication is used, the master waits a configurable amount of
   # time (in seconds) before starting the transfer in the hope that multiple slaves
   # will arrive and the transfer can be parallelized.
   #
   # With slow disks and fast (large bandwidth) networks, diskless replication
   # works better.
   repl-diskless-sync no
   
   # When diskless replication is enabled, it is possible to configure the delay
   # the server waits in order to spawn the child that transfers the RDB via socket
   # to the slaves.
   #
   # This is important since once the transfer starts, it is not possible to serve
   # new slaves arriving, that will be queued for the next RDB transfer, so the server
   # waits a delay in order to let more slaves arrive.
   #
   # The delay is specified in seconds, and by default is 5 seconds. To disable
   # it entirely just set it to 0 seconds and the transfer will start ASAP.
   repl-diskless-sync-delay 5
   
   # Slaves send PINGs to server in a predefined interval. It's possible to change
   # this interval with the repl_ping_slave_period option. The default value is 10
   # seconds.
   #
   # repl-ping-slave-period 10
   
   # The following option sets the replication timeout for:
   #
   # 1) Bulk transfer I/O during SYNC, from the point of view of slave.
   # 2) Master timeout from the point of view of slaves (data, pings).
   # 3) Slave timeout from the point of view of masters (REPLCONF ACK pings).
   #
   # It is important to make sure that this value is greater than the value
   # specified for repl-ping-slave-period otherwise a timeout will be detected
   # every time there is low traffic between the master and the slave.
   #
   # repl-timeout 60
   
   # Disable TCP_NODELAY on the slave socket after SYNC?
   #
   # If you select "yes" Redis will use a smaller number of TCP packets and
   # less bandwidth to send data to slaves. But this can add a delay for
   # the data to appear on the slave side, up to 40 milliseconds with
   # Linux kernels using a default configuration.
   #
   # If you select "no" the delay for data to appear on the slave side will
   # be reduced but more bandwidth will be used for replication.
   #
   # By default we optimize for low latency, but in very high traffic conditions
   # or when the master and slaves are many hops away, turning this to "yes" may
   # be a good idea.
   repl-disable-tcp-nodelay no
   
   # Set the replication backlog size. The backlog is a buffer that accumulates
   # slave data when slaves are disconnected for some time, so that when a slave
   # wants to reconnect again, often a full resync is not needed, but a partial
   # resync is enough, just passing the portion of data the slave missed while
   # disconnected.
   #
   # The bigger the replication backlog, the longer the time the slave can be
   # disconnected and later be able to perform a partial resynchronization.
   #
   # The backlog is only allocated once there is at least a slave connected.
   #
   # repl-backlog-size 1mb
   
   # After a master has no longer connected slaves for some time, the backlog
   # will be freed. The following option configures the amount of seconds that
   # need to elapse, starting from the time the last slave disconnected, for
   # the backlog buffer to be freed.
   #
   # A value of 0 means to never release the backlog.
   #
   # repl-backlog-ttl 3600
   
   # The slave priority is an integer number published by Redis in the INFO output.
   # It is used by Redis Sentinel in order to select a slave to promote into a
   # master if the master is no longer working correctly.
   #
   # A slave with a low priority number is considered better for promotion, so
   # for instance if there are three slaves with priority 10, 100, 25 Sentinel will
   # pick the one with priority 10, that is the lowest.
   #
   # However a special priority of 0 marks the slave as not able to perform the
   # role of master, so a slave with priority of 0 will never be selected by
   # Redis Sentinel for promotion.
   #
   # By default the priority is 100.
   slave-priority 100
   
   # It is possible for a master to stop accepting writes if there are less than
   # N slaves connected, having a lag less or equal than M seconds.
   #
   # The N slaves need to be in "online" state.
   #
   # The lag in seconds, that must be <= the specified value, is calculated from
   # the last ping received from the slave, that is usually sent every second.
   #
   # This option does not GUARANTEE that N replicas will accept the write, but
   # will limit the window of exposure for lost writes in case not enough slaves
   # are available, to the specified number of seconds.
   #
   # For example to require at least 3 slaves with a lag <= 10 seconds use:
   #
   # min-slaves-to-write 3
   # min-slaves-max-lag 10
   #
   # Setting one or the other to 0 disables the feature.
   #
   # By default min-slaves-to-write is set to 0 (feature disabled) and
   # min-slaves-max-lag is set to 10.
   
   ################################## SECURITY ###################################
   
   # Require clients to issue AUTH  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
   
   # 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 ""
   #
   # Please note that changing the name of commands that are logged into the
   # AOF file or transmitted to slaves may cause problems.
   
   ################################### LIMITS ####################################
   
   # 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
   
   # 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 
   
   # 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
   
   # 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
   
   ############################## 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
   
   # The name of the append only file (default: "appendonly.aof")
   
   appendfilename "appendonly.aof"
   
   # 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
   
   # 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
   
   # 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
   
   # An AOF file may be found to be truncated at the end during the Redis
   # startup process, when the AOF data gets loaded back into memory.
   # This may happen when the system where Redis is running
   # crashes, especially when an ext4 filesystem is mounted without the
   # data=ordered option (however this can't happen when Redis itself
   # crashes or aborts but the operating system still works correctly).
   #
   # Redis can either exit with an error when this happens, or load as much
   # data as possible (the default now) and start if the AOF file is found
   # to be truncated at the end. The following option controls this behavior.
   #
   # If aof-load-truncated is set to yes, a truncated AOF file is loaded and
   # the Redis server starts emitting a log to inform the user of the event.
   # Otherwise if the option is set to no, the server aborts with an error
   # and refuses to start. When the option is set to no, the user requires
   # to fix the AOF file using the "redis-check-aof" utility before to restart
   # the server.
   #
   # Note that if the AOF file will be found to be corrupted in the middle
   # the server will still exit with an error. This option only applies when
   # Redis will try to read more data from the AOF file but not enough bytes
   # will be found.
   aof-load-truncated yes
   
   ################################ LUA SCRIPTING  ###############################
   
   # Max execution time of a Lua script in milliseconds.
   #
   # If the maximum execution time is reached Redis will log that a script is
   # still in execution after the maximum allowed time and will start to
   # reply to queries with an error.
   #
   # When a long running script exceeds the maximum execution time only the
   # SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be
   # used to stop a script that did not yet called write commands. The second
   # is the only way to shut down the server in the case a write command was
   # already issued by the script but the user doesn't want to wait for the natural
   # termination of the script.
   #
   # Set it to 0 or a negative value for unlimited execution without warnings.
   lua-time-limit 5000
   
   ################################ REDIS CLUSTER  ###############################
   #
   # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   # WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however
   # in order to mark it as "mature" we need to wait for a non trivial percentage
   # of users to deploy it in production.
   # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   #
   # 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-6380.conf
   
   # Cluster node timeout is the amount of milliseconds a node must be unreachable
   # for it to be considered in failure state.
   # Most other internal time limits are multiple of the node timeout.
   #
   cluster-node-timeout 5000
   
   # A slave of a failing master will avoid to start a failover if its data
   # looks too old.
   #
   # There is no simple way for a slave to actually have a exact measure of
   # its "data age", so the following two checks are performed:
   #
   # 1) If there are multiple slaves able to failover, they exchange messages
   #    in order to try to give an advantage to the slave with the best
   #    replication offset (more data from the master processed).
   #    Slaves will try to get their rank by offset, and apply to the start
   #    of the failover a delay proportional to their rank.
   #
   # 2) Every single slave computes the time of the last interaction with
   #    its master. This can be the last ping or command received (if the master
   #    is still in the "connected" state), or the time that elapsed since the
   #    disconnection with the master (if the replication link is currently down).
   #    If the last interaction is too old, the slave will not try to failover
   #    at all.
   #
   # The point "2" can be tuned by user. Specifically a slave will not perform
   # the failover if, since the last interaction with the master, the time
   # elapsed is greater than:
   #
   #   (node-timeout * slave-validity-factor) + repl-ping-slave-period
   #
   # So for example if node-timeout is 30 seconds, and the slave-validity-factor
   # is 10, and assuming a default repl-ping-slave-period of 10 seconds, the
   # slave will not try to failover if it was not able to talk with the master
   # for longer than 310 seconds.
   #
   # A large slave-validity-factor may allow slaves with too old data to failover
   # a master, while a too small value may prevent the cluster from being able to
   # elect a slave at all.
   #
   # For maximum availability, it is possible to set the slave-validity-factor
   # to a value of 0, which means, that slaves will always try to failover the
   # master regardless of the last time they interacted with the master.
   # (However they'll always try to apply a delay proportional to their
   # offset rank).
   #
   # Zero is the only value able to guarantee that when all the partitions heal
   # the cluster will always be able to continue.
   #
   # cluster-slave-validity-factor 10
   
   # Cluster slaves are able to migrate to orphaned masters, that are masters
   # that are left without working slaves. This improves the cluster ability
   # to resist to failures as otherwise an orphaned master can't be failed over
   # in case of failure if it has no working slaves.
   #
   # Slaves migrate to orphaned masters only if there are still at least a
   # given number of other working slaves for their old master. This number
   # is the "migration barrier". A migration barrier of 1 means that a slave
   # will migrate only if there is at least 1 other working slave for its master
   # and so forth. It usually reflects the number of slaves you want for every
   # master in your cluster.
   #
   # Default is 1 (slaves migrate only if their masters remain with at least
   # one slave). To disable migration just set it to a very large value.
   # A value of 0 can be set but is useful only for debugging and dangerous
   # in production.
   #
   # cluster-migration-barrier 1
   
   # By default Redis Cluster nodes stop accepting queries if they detect there
   # is at least an hash slot uncovered (no available node is serving it).
   # This way if the cluster is partially down (for example a range of hash slots
   # are no longer covered) all the cluster becomes, eventually, unavailable.
   # It automatically returns available as soon as all the slots are covered again.
   #
   # However sometimes you want the subset of the cluster which is working,
   # to continue to accept queries for the part of the key space that is still
   # covered. In order to do so, just set the cluster-require-full-coverage
   # option to no.
   #
   # cluster-require-full-coverage yes
   
   # In order to setup your cluster make sure to read the documentation
   # available at http://redis.io web site.
   
   ################################## SLOW LOG ###################################
   
   # The Redis Slow Log is a system to log queries that exceeded a specified
   # execution time. The execution time does not include the I/O operations
   # like talking with the client, sending the reply and so forth,
   # but just the time needed to actually execute the command (this is the only
   # stage of command execution where the thread is blocked and can not serve
   # other requests in the meantime).
   #
   # You can configure the slow log with two parameters: one tells Redis
   # what is the execution time, in microseconds, to exceed in order for the
   # command to get logged, and the other parameter is the length of the
   # slow log. When a new command is logged the oldest one is removed from the
   # queue of logged commands.
   
   # The following time is expressed in microseconds, so 1000000 is equivalent
   # to one second. Note that a negative number disables the slow log, while
   # a value of zero forces the logging of every command.
   slowlog-log-slower-than 10000
   
   # There is no limit to this length. Just be aware that it will consume memory.
   # You can reclaim memory used by the slow log with SLOWLOG RESET.
   slowlog-max-len 128
   
   ################################ LATENCY MONITOR ##############################
   
   # The Redis latency monitoring subsystem samples different operations
   # at runtime in order to collect data related to possible sources of
   # latency of a Redis instance.
   #
   # Via the LATENCY command this information is available to the user that can
   # print graphs and obtain reports.
   #
   # The system only logs operations that were performed in a time equal or
   # greater than the amount of milliseconds specified via the
   # latency-monitor-threshold configuration directive. When its value is set
   # to zero, the latency monitor is turned off.
   #
   # By default latency monitoring is disabled since it is mostly not needed
   # if you don't have latency issues, and collecting data has a performance
   # impact, that while very small, can be measured under big load. Latency
   # monitoring can easily be enabled at runtime using the command
   # "CONFIG SET latency-monitor-threshold " if needed.
   latency-monitor-threshold 0
   
   ############################# EVENT NOTIFICATION ##############################
   
   # Redis can notify Pub/Sub clients about events happening in the key space.
   # This feature is documented at http://redis.io/topics/notifications
   #
   # For instance if keyspace events notification is enabled, and a client
   # performs a DEL operation on key "foo" stored in the Database 0, two
   # messages will be published via Pub/Sub:
   #
   # PUBLISH __keyspace@0__:foo del
   # PUBLISH __keyevent@0__:del foo
   #
   # It is possible to select the events that Redis will notify among a set
   # of classes. Every class is identified by a single character:
   #
   #  K     Keyspace events, published with __keyspace@__ prefix.
   #  E     Keyevent events, published with __keyevent@__ prefix.
   #  g     Generic commands (non-type specific) like DEL, EXPIRE, RENAME, ...
   #  $     String commands
   #  l     List commands
   #  s     Set commands
   #  h     Hash commands
   #  z     Sorted set commands
   #  x     Expired events (events generated every time a key expires)
   #  e     Evicted events (events generated when a key is evicted for maxmemory)
   #  A     Alias for g$lshzxe, so that the "AKE" string means all the events.
   #
   #  The "notify-keyspace-events" takes as argument a string that is composed
   #  of zero or multiple characters. The empty string means that notifications
   #  are disabled.
   #
   #  Example: to enable list and generic events, from the point of view of the
   #           event name, use:
   #
   #  notify-keyspace-events Elg
   #
   #  Example 2: to get the stream of the expired keys subscribing to channel
   #             name __keyevent@0__:expired use:
   #
   #  notify-keyspace-events Ex
   #
   #  By default all notifications are disabled because most users don't need
   #  this feature and the feature has some overhead. Note that if you don't
   #  specify at least one of K or E, no events will be delivered.
   notify-keyspace-events ""
   
   ############################### ADVANCED CONFIG ###############################
   
   # Hashes are encoded using a memory efficient data structure when they have a
   # small number of entries, and the biggest entry does not exceed a given
   # threshold. These thresholds can be configured using the following directives.
   hash-max-ziplist-entries 512
   hash-max-ziplist-value 64
   
   # Lists are also encoded in a special way to save a lot of space.
   # The number of entries allowed per internal list node can be specified
   # as a fixed maximum size or a maximum number of elements.
   # For a fixed maximum size, use -5 through -1, meaning:
   # -5: max size: 64 Kb  <-- not recommended for normal workloads
   # -4: max size: 32 Kb  <-- not recommended
   # -3: max size: 16 Kb  <-- probably not recommended
   # -2: max size: 8 Kb   <-- good
   # -1: max size: 4 Kb   <-- good
   # Positive numbers mean store up to _exactly_ that number of elements
   # per list node.
   # The highest performing option is usually -2 (8 Kb size) or -1 (4 Kb size),
   # but if your use case is unique, adjust the settings as necessary.
   list-max-ziplist-size -2
   
   # Lists may also be compressed.
   # Compress depth is the number of quicklist ziplist nodes from *each* side of
   # the list to *exclude* from compression.  The head and tail of the list
   # are always uncompressed for fast push/pop operations.  Settings are:
   # 0: disable all list compression
   # 1: depth 1 means "don't start compressing until after 1 node into the list,
   #    going from either the head or tail"
   #    So: [head]->node->node->...->node->[tail]
   #    [head], [tail] will always be uncompressed; inner nodes will compress.
   # 2: [head]->[next]->node->node->...->node->[prev]->[tail]
   #    2 here means: don't compress head or head->next or tail->prev or tail,
   #    but compress all nodes between them.
   # 3: [head]->[next]->[next]->node->node->...->node->[prev]->[prev]->[tail]
   # etc.
   list-compress-depth 0
   
   # Sets have a special encoding in just one case: when a set is composed
   # of just strings that happen to be integers in radix 10 in the range
   # of 64 bit signed integers.
   # The following configuration setting sets the limit in the size of the
   # set in order to use this special memory saving encoding.
   set-max-intset-entries 512
   
   # Similarly to hashes and lists, sorted sets are also specially encoded in
   # order to save a lot of space. This encoding is only used when the length and
   # elements of a sorted set are below the following limits:
   zset-max-ziplist-entries 128
   zset-max-ziplist-value 64
   
   # HyperLogLog sparse representation bytes limit. The limit includes the
   # 16 bytes header. When an HyperLogLog using the sparse representation crosses
   # this limit, it is converted into the dense representation.
   #
   # A value greater than 16000 is totally useless, since at that point the
   # dense representation is more memory efficient.
   #
   # The suggested value is ~ 3000 in order to have the benefits of
   # the space efficient encoding without slowing down too much PFADD,
   # which is O(N) with the sparse encoding. The value can be raised to
   # ~ 10000 when CPU is not a concern, but space is, and the data set is
   # composed of many HyperLogLogs with cardinality in the 0 - 15000 range.
   hll-sparse-max-bytes 3000
   
   # Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in
   # order to help rehashing the main Redis hash table (the one mapping top-level
   # keys to values). The hash table implementation Redis uses (see dict.c)
   # performs a lazy rehashing: the more operation you run into a hash table
   # that is rehashing, the more rehashing "steps" are performed, so if the
   # server is idle the rehashing is never complete and some more memory is used
   # by the hash table.
   #
   # The default is to use this millisecond 10 times every second in order to
   # actively rehash the main dictionaries, freeing memory when possible.
   #
   # If unsure:
   # use "activerehashing no" if you have hard latency requirements and it is
   # not a good thing in your environment that Redis can reply from time to time
   # to queries with 2 milliseconds delay.
   #
   # use "activerehashing yes" if you don't have such hard requirements but
   # want to free memory asap when possible.
   activerehashing yes
   
   # The client output buffer limits can be used to force disconnection of clients
   # that are not reading data from the server fast enough for some reason (a
   # common reason is that a Pub/Sub client can't consume messages as fast as the
   # publisher can produce them).
   #
   # The limit can be set differently for the three different classes of clients:
   #
   # normal -> normal clients including MONITOR clients
   # slave  -> slave clients
   # pubsub -> clients subscribed to at least one pubsub channel or pattern
   #
   # The syntax of every client-output-buffer-limit directive is the following:
   #
   # client-output-buffer-limit    
   #
   # A client is immediately disconnected once the hard limit is reached, or if
   # the soft limit is reached and remains reached for the specified number of
   # seconds (continuously).
   # So for instance if the hard limit is 32 megabytes and the soft limit is
   # 16 megabytes / 10 seconds, the client will get disconnected immediately
   # if the size of the output buffers reach 32 megabytes, but will also get
   # disconnected if the client reaches 16 megabytes and continuously overcomes
   # the limit for 10 seconds.
   #
   # By default normal clients are not limited because they don't receive data
   # without asking (in a push way), but just after a request, so only
   # asynchronous clients may create a scenario where data is requested faster
   # than it can read.
   #
   # Instead there is a default limit for pubsub and slave clients, since
   # subscribers and slaves receive data in a push fashion.
   #
   # Both the hard or the soft limit can be disabled by setting them to zero.
   client-output-buffer-limit normal 0 0 0
   client-output-buffer-limit slave 256mb 64mb 60
   client-output-buffer-limit pubsub 32mb 8mb 60
   
   # Redis calls an internal function to perform many background tasks, like
   # closing connections of clients in timeout, purging expired keys that are
   # never requested, and so forth.
   #
   # Not all tasks are performed with the same frequency, but Redis checks for
   # tasks to perform according to the specified "hz" value.
   #
   # By default "hz" is set to 10. Raising the value will use more CPU when
   # Redis is idle, but at the same time will make Redis more responsive when
   # there are many keys expiring at the same time, and timeouts may be
   # handled with more precision.
   #
   # The range is between 1 and 500, however a value over 100 is usually not
   # a good idea. Most users should use the default of 10 and raise this up to
   # 100 only in environments where very low latency is required.
   hz 10
   
   # When a child rewrites the AOF file, if the following option is enabled
   # the file will be fsync-ed every 32 MB of data generated. This is useful
   # in order to commit the file to the disk more incrementally and avoid
   # big latency spikes.
   aof-rewrite-incremental-fsync yes