Redis配置文件（1）units/includes/GENERAL/SECURITY/LIMITS

redis.conf文件

在Linux进行文件的查看！

units单位：

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

 1  配置大小单位,开头定义了一些基本的度量单位，只支持bytes，不支持bit

 2  对大小写不敏感

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.
   #
   # 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 runti     me.
   #
   # 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

和我们的Struts2配置文件类似，可以通过includes包含，redis.conf可以作为总闸，包含其他

GENERAL

 # 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 fi     le
 # 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_6379.pid

 # 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 daemoniz     ed.
 daemonize yes

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

# 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

tcp-backlog
设置tcp的backlog，backlog其实是一个连接队列，backlog队列总和=未完成三次握手队列 + 已经完成三次握手队列。
在高并发环境下你需要一个高backlog值来避免慢客户端连接问题。注意Linux内核会将这个值减小到
/proc/sys/net/core/somaxconn的值，所以需要确认增大somaxconn和tcp_max_syn_backlog两个值
来达到想要的效果

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

# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bind 127.0.0.1

# 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  seconds, which is the new
# Redis default starting with Redis 3.2..
tcp-keepalive 300
单位为秒，如果设置为0，则不会进行Keepalive检测，建议设置成60

# 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
日志级别

# 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 ""
日志的名字

# Set the number of databases. The default database is DB , you can select
# a different one on a per-connection basis using SELECT <dbid> where
# dbid is a number between  and 'databases'-
databases 16
系统默认的库16个
默认使用0库

# 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   是否把日志输出到syslog中
系统日志默认时关着
# Specify the syslog identity.
# syslog-ident redis  指定syslog里的日志标志
设备以redis开头
# Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
# syslog-facility local0
指定syslog设备，值可以是USER或LOCAL0-LOCAL7
默认使用local0

SECURITY安全

访问密码的查看、设置和取消

设置密码：

config set requirepass " "

;

改为空的时候默认没有密码！

 ################################## SECURITY ###################################

 # 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.

要求必须auth + password 在任何命令之前

Redis一般做的是缓存，不是安全，而且系统会认为Linux是在安全的环境下....

LIMITS限制

maxclients:

设置redis同时可以与多少个客户端进行连接。默认情况下为10000个客户端。当你
无法设置进程文件句柄限制时，redis会设置为当前的文件句柄限制值减去32，因为redis会为自
身内部处理逻辑留一些句柄出来。如果达到了此限制，redis则会拒绝新的连接请求，并且向这
些连接请求方发出“max number of clients reached”以作回应。

509 # Once the limit is reached Redis will close all the new connections sending

510 # an error 'max number of clients reached'.

511 #

512 # maxclients 10000

默认情况下为10000个客户端

maxmemory

设置redis可以使用的内存量。一旦到达内存使用上限，redis将会试图移除内部数据，移除规则可以通过maxmemory-policy来指定。
如果redis无法根据移除规则来移除内存中的数据，或者设置了“不允许移除”，
那么redis则会针对那些需要申请内存的指令返回错误信息，比如SET、LPUSH等。
但是对于无内存申请的指令，仍然会正常响应，比如GET等。如果你的redis是主redis（说明你的redis有从redis），
那么在设置内存使用上限时，需要在系统中留出一些内存空间给同步队列缓存，只有在你设置的是“不移除”的情况下，才不用考虑这个因素

533 # In short... if you have slaves attached it is suggested that you set a lower

534 # limit for maxmemory so that there is some free RAM on the system for slave

535 # output buffers (but this is not needed if the policy is 'noeviction').

537 # maxmemory <bytes>

maxmemory-policy:

最大缓存清楚策略

（）volatile-lru：使用LRU算法移除key，只对设置了过期时间的键
（）allkeys-lru：使用LRU算法移除key
（）volatile-random：在过期集合中移除随机的key，只对设置了过期时间的键
（）allkeys-random：移除随机的key
（）volatile-ttl：移除那些TTL值最小的key，即那些最近要过期的key
（）noeviction：不进行移除。针对写操作，只是返回错误信息
LRU 算法或者 TTL 算法都是不是很精确算法，而是 个近似算法。

539 # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory

540 # is reached. You can select among five behaviors:

541 #

542 # volatile-lru -> remove the key with an expire set using an LRU algorithm

543 # allkeys-lru -> remove any key according to the LRU algorithm

544 # volatile-random -> remove a random key with an expire set

545 # allkeys-random -> remove a random key, any key

546 # volatile-ttl -> remove the key with the nearest expire time (minor TTL)

547 # noeviction -> don't expire at all, just return an error on write operations

maxmemory-samples

设置样本数量，LRU算法和最小TTL算法都并非是精确的算法，而是估算值，所以你可以设置样本的大小，
redis默认会检查这么多个key并选择其中LRU的那个

562 # LRU and minimal TTL algorithms are not precise algorithms but approximated

563 # algorithms (in order to save memory), so you can tune it for speed or

564 # accuracy. For default Redis will check five keys and pick the one that was

565 # used less recently, you can change the sample size using the following

566 # configuration directive.

568 # The default of 5 produces good enough results. 10 Approximates very closely

569 # true LRU but costs a bit more CPU. 3 is very fast but not very accurate.

571 # maxmemory-samples 5