提示：redis集群配置

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前言

项目需要，使用到redis集群，搭建之前借助博客记录下自己的采坑之旅，也作为后续查阅的资料，有不妥或者记录不够详尽之处，还请见谅。
Redis作为一种高性能的内存数据库，普遍用于目前主流的分布式架构系统中。为了提高系统的容错率，使用多实例的Redis也是必不可免的，但同样复杂度也相比单实例高出很多。

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提示：以下是本篇文章正文内容，下面案例可供参考

一、redis集群模式

redis有三种集群方式：主从复制，哨兵模式和集群

1.主从复制

有多个redis节点，其中，有且仅有一个 为主节点Master。从节点Slave可以有多个。
只要网络连接正常，Master会一直将自己的数据更新同步给Slaves，保持主从同步。
特点： master 读写，从节点只读
缺陷： master宕机，会影响数据写入，如部分数据未推至slave重启或切换IP后会导致部分数据丢失，容错性较差
主从模型可以提高读的能力，在一定程度上缓解了写的能力。因为能写仍然只有Master节点一个，可以将读的操作全部移交到从节点上，变相提高了写能力。

2.哨兵模式

在主从复制实现之后，如果想对master进行监控，Redis提供了一种哨兵机制，哨兵的含义就是监控Redis系统的运行状态，并做相应的响应。
特点： 哨兵模式是基于主从模式的，所有主从的优点，哨兵模式都具有。主从可以自动切换，系统更健壮，可用性更高。
缺陷： Redis较难支持在线扩容，在集群容量达到上限时在线扩容会变得很复杂。

3.Cluster集群

redis的哨兵模式基本已经可以实现高可用，读写分离 ，但是在这种模式下每台redis服务器都存储相同的数据，很浪费内存，所以在redis3.0上加入了cluster模式，实现的redis的分布式存储，也就是说每台redis节点上存储不同的内容
特点：
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。
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。
客户端与redis节点直连,不需要中间代理层.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。

二、集群服务搭建

已经对redis相关模式有了初步了解，根据项目现状，着手搭建集群模式，后续有时间再更新主从，哨兵等模式，综上三台以上才能构建集群，为了实现集群的高可用，每台需要部署一个从节点，所以需要6台，开发环境资源有限，所以构建伪集群（单台服务部署两个以上实例）

1.环境准备

本地安装版本为 redis-6.2.6，请参照 redis离线安装

2.安装多实例

复制节点1

mkdir /root/app/redis-cluster/redis-6.2.6-214.1 # 创建节点目录
cd /root/app/redis-6.2.6
cp -r bin /root/app/redis-cluster/redis-6.2.6-214.1/bin  
cp redis.conf /root/app/redis-cluster/redis-6.2.6-214.1/ #cp配置文件

复制节点2

mkdir /root/app/redis-cluster/redis-6.2.6-214.2 # 创建节点目录
cd /root/app/redis-6.2.6
cp -r bin /root/app/redis-cluster/redis-6.2.6-214.2/bin  
cp redis.conf /root/app/redis-cluster/redis-6.2.6-214.2/ #cp配置文件

更改节点配置文件如下: 主要更改端口号

port 5906

3.集群配置更改

protected-mode no
port 5906
tcp-backlog 511
timeout 0
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.
# When Redis is supervised by upstart or systemd, this parameter has no impact.
daemonize yes
pidfile /var/run/redis_6379.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 ""
databases 16# By default Redis shows an ASCII art logo only when started to log to the
# standard output and if the standard output is a TTY and syslog logging is
# disabled. Basically this means that normally a logo is displayed only in
# interactive sessions.
#
# However it is possible to force the pre-4.0 behavior and always show a
# ASCII art logo in startup logs by setting the following option to yes.
always-show-logo no# By default, Redis modifies the process title (as seen in 'top' and 'ps') to
# provide some runtime information. It is possible to disable this and leave
# the process name as executed by setting the following to no.
set-proc-title yes
proc-title-template "{title} {listen-addr} {server-mode}"
stop-writes-on-bgsave-error yes# Compress string objects using LZF when dump .rdb databases?
# By default compression is enabled 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
# An alternative (and sometimes better) way to obtain the same effect is
# to use diskless replication on both master and replicas instances. However
# in the case of replicas, diskless is not always an option.
rdb-del-sync-files no# 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 ./
#masterauth <master-password>
replica-serve-stale-data yes
replica-read-only yes
repl-diskless-sync no
# 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
repl-diskless-load disabled
repl-disable-tcp-nodelay no
# By default the priority is 100.
replica-priority 100# ACL LOG
#
# The ACL Log tracks failed commands and authentication events associated
# with ACLs. The ACL Log is useful to troubleshoot failed commands blocked 
# by ACLs. The ACL Log is stored in memory. You can reclaim memory with 
# ACL LOG RESET. Define the maximum entry length of the ACL Log below.
acllog-max-len 128
# The requirepass is not compatable with aclfile option and the ACL LOAD
# command, these will cause requirepass to be ignored.
#
requirepass ew5T4K3#203lwh# In all the above cases the default is to delete objects in a blocking way,
# like if DEL was called. However you can configure each case specifically
# in order to instead release memory in a non-blocking way like if UNLINK
# was called, using the following configuration directives.lazyfree-lazy-eviction no
lazyfree-lazy-expire no
lazyfree-lazy-server-del no
replica-lazy-flush no# It is also possible, for the case when to replace the user code DEL calls
# with UNLINK calls is not easy, to modify the default behavior of the DEL
# command to act exactly like UNLINK, using the following configuration
# directive:lazyfree-lazy-user-del no# FLUSHDB, FLUSHALL, and SCRIPT FLUSH support both asynchronous and synchronous
# deletion, which can be controlled by passing the [SYNC|ASYNC] flags into the
# commands. When neither flag is passed, this directive will be used to determine
# if the data should be deleted asynchronously.lazyfree-lazy-user-flush no################################ THREADED I/O #################################
# no:       Don't make changes to oom-score-adj (default).
# yes:      Alias to "relative" see below.
# absolute: Values in oom-score-adj-values are written as is to the kernel.
# relative: Values are used relative to the initial value of oom_score_adj when
#           the server starts and are then clamped to a range of -1000 to 1000.
#           Because typically the initial value is 0, they will often match the
#           absolute values.
oom-score-adj no# When oom-score-adj is used, this directive controls the specific values used
# for master, replica and background child processes. Values range -2000 to
# 2000 (higher means more likely to be killed).
#
# Unprivileged processes (not root, and without CAP_SYS_RESOURCE capabilities)
# can freely increase their value, but not decrease it below its initial
# settings. This means that setting oom-score-adj to "relative" and setting the
# oom-score-adj-values to positive values will always succeed.
oom-score-adj-values 0 200 800#################### KERNEL transparent hugepage CONTROL ####################### Usually the kernel Transparent Huge Pages control is set to "madvise" or
# or "never" by default (/sys/kernel/mm/transparent_hugepage/enabled), in which
# case this config has no effect. On systems in which it is set to "always",
# redis will attempt to disable it specifically for the redis process in order
# to avoid latency problems specifically with fork(2) and CoW.
# If for some reason you prefer to keep it enabled, you can set this config to
# "no" and the kernel global to "always".disable-thp yes
# Please check https://redis.io/topics/persistence for more information.
appendonly no
# The name of the append only file (default: "appendonly.aof")
appendfilename "appendonly.aof"
# appendfsync always
appendfsync everysec
# appendfsync no
# 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
# 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
# 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# When loading, Redis recognizes that the AOF file starts with the "REDIS"
# string and loads the prefixed RDB file, then continues loading the AOF
# tail.
aof-use-rdb-preamble yes
# Set it to 0 or a negative value for unlimited execution without warnings.
lua-time-limit 5000################################ 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# 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 a multiple of the node timeout.
#
# cluster-node-timeout 15000# A replica of a failing master will avoid to start a failover if its data
# looks too old.
#
# There is no simple way for a replica to actually have an exact measure of
# its "data age", so the following two checks are performed:
#
# 1) If there are multiple replicas able to failover, they exchange messages
#    in order to try to give an advantage to the replica with the best
#    replication offset (more data from the master processed).
#    Replicas 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 replica 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 replica will not try to failover
#    at all.
#
# The point "2" can be tuned by user. Specifically a replica will not perform
# the failover if, since the last interaction with the master, the time
# elapsed is greater than:
#
#   (node-timeout * cluster-replica-validity-factor) + repl-ping-replica-period
#
# So for example if node-timeout is 30 seconds, and the cluster-replica-validity-factor
# is 10, and assuming a default repl-ping-replica-period of 10 seconds, the
# replica will not try to failover if it was not able to talk with the master
# for longer than 310 seconds.
#
# A large cluster-replica-validity-factor may allow replicas with too old data to failover
# a master, while a too small value may prevent the cluster from being able to
# elect a replica at all.
#
# For maximum availability, it is possible to set the cluster-replica-validity-factor
# to a value of 0, which means, that replicas 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-replica-validity-factor 10# Cluster replicas are able to migrate to orphaned masters, that are masters
# that are left without working replicas. 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 replicas.
#
# Replicas migrate to orphaned masters only if there are still at least a
# given number of other working replicas for their old master. This number
# is the "migration barrier". A migration barrier of 1 means that a replica
# will migrate only if there is at least 1 other working replica for its master
# and so forth. It usually reflects the number of replicas you want for every
# master in your cluster.
#
# Default is 1 (replicas migrate only if their masters remain with at least
# one replica). To disable migration just set it to a very large value or
# set cluster-allow-replica-migration to 'no'.
# A value of 0 can be set but is useful only for debugging and dangerous
# in production.
#
# cluster-migration-barrier 1# Turning off this option allows to use less automatic cluster configuration.
# It both disables migration to orphaned masters and migration from masters
# that became empty.
#
# Default is 'yes' (allow automatic migrations).
#
# cluster-allow-replica-migration yes# By default Redis Cluster nodes stop accepting queries if they detect there
# is at least a 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# This option, when set to yes, prevents replicas from trying to failover its
# master during master failures. However the replica can still perform a
# manual failover, if forced to do so.
#
# This is useful in different scenarios, especially in the case of multiple
# data center operations, where we want one side to never be promoted if not
# in the case of a total DC failure.
#
# cluster-replica-no-failover no# This option, when set to yes, allows nodes to serve read traffic while the
# the cluster is in a down state, as long as it believes it owns the slots. 
#
# This is useful for two cases.  The first case is for when an application 
# doesn't require consistency of data during node failures or network partitions.
# One example of this is a cache, where as long as the node has the data it
# should be able to serve it. 
#
# The second use case is for configurations that don't meet the recommended  
# three shards but want to enable cluster mode and scale later. A 
# master outage in a 1 or 2 shard configuration causes a read/write outage to the
# entire cluster without this option set, with it set there is only a write outage.
# Without a quorum of masters, slot ownership will not change automatically. 
#
# cluster-allow-reads-when-down no# In order to setup your cluster make sure to read the documentation
# available at https://redis.io web site.########################## CLUSTER DOCKER/NAT support  ########################
# 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-threshold 0
#  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 ""############################### GOPHER SERVER #################################
# 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
# 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
list-compress-depth 0
# 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
# composed of many HyperLogLogs with cardinality in the 0 - 15000 range.
hll-sparse-max-bytes 3000
# max entries limit by setting max-bytes to 0 and max-entries to the desired
# value.
stream-node-max-bytes 4096
stream-node-max-entries 100
# use "activerehashing yes" if you don't have such hard requirements but
# want to free memory asap when possible.
activerehashing yes
client-output-buffer-limit normal 0 0 0
client-output-buffer-limit replica 256mb 64mb 60
client-output-buffer-limit pubsub 32mb 8mb 60
hz 10
# instance will use very little CPU time while a busy instance will be
# more responsive.
dynamic-hz yes
# big latency spikes.
aof-rewrite-incremental-fsync yes
# big latency spikes.
rdb-save-incremental-fsync yes
# Maximum number of set/hash/zset/list fields that will be processed from
# the main dictionary scan
# active-defrag-max-scan-fields 1000
# Jemalloc background thread for purging will be enabled by default
jemalloc-bg-thread yes

4.创建集群

使用任意一个节点创建集群，这里使用redis7000结点创建（注意，一次创建，永久使用）

redis7000/src/redis-cli --cluster create  
192.168.124.23:7000 192.168.124.23:7001  
192.168.124.24:7002 192.168.124.24:7003  
192.168.124.25:7004 192.168.124.25:7005 --cluster-replicas 1

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总结

提示：这里对文章进行总结：
例如：以上就是今天要讲的内容，本文仅仅简单介绍了pandas的使用，而pandas提供了大量能使我们快速便捷地处理数据的函数和方法。