Redis配置文件解读

Redis配置文件参数说明: 1. Redis默认不是以守护进程的方式运行，可以通过该配置项修改，使用yes启用守护进程daemonize no2. 当Redis以守护进程方式运行时，Redis默认会把pid写入/var/run/redis.pid文件，可以通过pidfile指定pidfile /var/run/redis.pid3. 指定Redis监听端口，默认端口为6379，作者在自己的一篇博文中解释了为什么选用6379作为默认端口，因为6379在手机按键上MERZ对应的号码，而MERZ取自意大利歌女Alessia Merz的名字port 63794. 绑定的主机地址bind 127.0.0.15.当客户端闲置多长时间后关闭连接，如果指定为0，表示关闭该功能timeout 3006. 指定日志记录级别，Redis总共支持四个级别：debug、verbose、notice、warning，默认为verboseloglevel verbose7. 日志记录方式，默认为标准输出，如果配置Redis为守护进程方式运行，而这里又配置为日志记录方式为标准输出，则日志将会发送给/dev/nulllogfile stdout8. 设置数据库的数量，默认数据库为0，可以使用SELECT <dbid>命令在连接上指定数据库iddatabases 169. 指定在多长时间内，有多少次更新操作，就将数据同步到数据文件，可以多个条件配合save <seconds> <changes>Redis默认配置文件中提供了三个条件：save 900 1save 300 10save 60 10000分别表示900秒（15分钟）内有1个更改，300秒（5分钟）内有10个更改以及60秒内有10000个更改。 10. 指定存储至本地数据库时是否压缩数据，默认为yes，Redis采用LZF压缩，如果为了节省CPU时间，可以关闭该选项，但会导致数据库文件变的巨大rdbcompression yes11. 指定本地数据库文件名，默认值为dump.rdbdbfilename dump.rdb12. 指定本地数据库存放目录dir ./13. 设置当本机为slav服务时，设置master服务的IP地址及端口，在Redis启动时，它会自动从master进行数据同步slaveof <masterip> <masterport>14. 当master服务设置了密码保护时，slav服务连接master的密码masterauth <master-password>15. 设置Redis连接密码，如果配置了连接密码，客户端在连接Redis时需要通过AUTH <password>命令提供密码，默认关闭requirepass foobared16. 设置同一时间最大客户端连接数，默认无限制，Redis可以同时打开的客户端连接数为Redis进程可以打开的最大文件描述符数，如果设置 maxclients 0，表示不作限制。当客户端连接数到达限制时，Redis会关闭新的连接并向客户端返回max number of clients reached错误信息maxclients 12817. 指定Redis最大内存限制，Redis在启动时会把数据加载到内存中，达到最大内存后，Redis会先尝试清除已到期或即将到期的Key，当此方法处理后，仍然到达最大内存设置，将无法再进行写入操作，但仍然可以进行读取操作。Redis新的vm机制，会把Key存放内存，Value会存放在swap区maxmemory <bytes>18. 指定是否在每次更新操作后进行日志记录，Redis在默认情况下是异步的把数据写入磁盘，如果不开启，可能会在断电时导致一段时间内的数据丢失。因为 redis本身同步数据文件是按上面save条件来同步的，所以有的数据会在一段时间内只存在于内存中。默认为noappendonly no19. 指定更新日志文件名，默认为appendonly.aofappendfilename appendonly.aof20. 指定更新日志条件，共有3个可选值：
no：表示等操作系统进行数据缓存同步到磁盘（快）
always：表示每次更新操作后手动调用fsync（）将数据写到磁盘（慢，安全）
everysec：表示每秒同步一次（折衷，默认值）appendfsync everysec 21. 指定是否启用虚拟内存机制，默认值为no，简单的介绍一下，VM机制将数据分页存放，由Redis将访问量较少的页即冷数据swap到磁盘上，访问多的页面由磁盘自动换出到内存中（在后面的文章我会仔细分析Redis的VM机制）vm-enabled no22. 虚拟内存文件路径，默认值为/tmp/redis.swap，不可多个Redis实例共享vm-swap-file /tmp/redis.swap23. 将所有大于vm-max-memory的数据存入虚拟内存,无论vm-max-memory设置多小,所有索引数据都是内存存储的（Redis的索引数据就是keys）,也就是说,当vm-max-memory设置为0的时候,其实是所有value都存在于磁盘。默认值为0vm-max-memory 024. Redis swap文件分成了很多的page，一个对象可以保存在多个page上面，但一个page上不能被多个对象共享，vm-page-size是要根据存储的数据大小来设定的，作者建议如果存储很多小对象，page大小最好设置为32或者64bytes；如果存储很大大对象，则可以使用更大的page，如果不确定，就使用默认值vm-page-size 3225. 设置swap文件中的page数量，由于页表（一种表示页面空闲或使用的bitmap）是在放在内存中的，，在磁盘上每8个pages将消耗1byte的内存。vm-pages 13421772826. 设置访问swap文件的线程数,最好不要超过机器的核数,如果设置为0,那么所有对swap文件的操作都是串行的，可能会造成比较长时间的延迟。默认值为4vm-max-threads 427. 设置在向客户端应答时，是否把较小的包合并为一个包发送，默认为开启glueoutputbuf yes28. 指定在超过一定的数量或者最大的元素超过某一临界值时，采用一种特殊的哈希算法hash-max-zipmap-entries 64hash-max-zipmap-value 51229. 指定是否激活重置哈希，默认为开启（后面在介绍Redis的哈希算法时具体介绍）activerehashing yes30. 指定包含其它的配置文件，可以在同一主机上多个Redis实例之间使用同一份配置文件，而同时各个实例又拥有自己的特定配置文件include /path/to/local.conf ------------------------------------------------------------------------------------------------------------------------------

完整配置文件：

# Redis configuration file example # 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 no # When run as a daemon, Redis write a pid file in /var/run/redis.pid by default.# You can specify a custom pid file location here.pidfile /var/run/redis.pid # Accept connections on the specified port, default is 6379port 6379 # If you want you can bind a single interface, if the bind option is not# specified all the interfaces will listen for connections.## bind 127.0.0.1 # Close the connection after a client is idle for N seconds （0 to disable）timeout 300 # Set server verbosity to "debug"# it can be one of:# debug （a lot of information, useful for development/testing）# notice （moderately verbose, what you want in production probably）# warning （only very important / critical messages are logged）loglevel debug # Specify the log file name. Also "stdout" can be used to force# the demon to log on the standard output. Note that if you use standard# output for logging but daemonize, logs will be sent to /dev/nulllogfile stdout # 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"-1databases 16 ################################ SNAPSHOTTING （快照）################################### 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 changedsave 900 1save 300 10save 60 10000 # 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 # The filename where to dump the DBdbfilename dump.rdb # For default save/load DB in/from the working directory# Note that you must specify a directory not a file name.dir ./ ################################# REPLICATION ################################# # Master-Slave replication. Use slaveof to make a Redis instance a copy of# another Redis server. Note that the configuration is local to the slave# so for example it is possible to configure the slave to save the DB with a# different interval, or to listen to another port, and so on.## slaveof <masterip> <masterport> # 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 <master-password> ################################## 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.## This should stay commented out for backward compatibility and because most# people do not need auth （e.g. they run their own servers）.## requirepass foobared ################################### LIMITS #################################### # Set the max number of connected clients at the same time. By default there# is no limit, and it"s up to the number of file descriptors the Redis process# is able to open. The special value "0" means no limts.# Once the limit is reached Redis will close all the new connections sending# an error "max number of clients reached".## maxclients 128 # Don"t use more memory than the specified amount of bytes.# When the memory limit is reached Redis will try to remove keys with an# EXPIRE set. It will try to start freeing keys that are going to expire# in little time and preserve keys with a longer time to live.# Redis will also try to remove objects from free lists if possible.## If all this fails, Redis will start to reply with errors to commands# that will use more memory, like SET, LPUSH, and so on, and will continue# to reply to most read-only commands like GET.## WARNING: maxmemory can be a good idea mainly if you want to use Redis as a# "state" server or cache, not as a real DB. When Redis is used as a real# database the memory usage will grow over the weeks, it will be obvious if# it is going to use too much memory in the long run, and you"ll have the time# to upgrade. With maxmemory after the limit is reached you"ll start to get# errors for write operations, and this may even lead to DB inconsistency.## maxmemory <bytes> ############################## APPEND ONLY MODE ############################### # By default Redis asynchronously（异步） dumps the dataset on disk. If you can live# with the idea that the latest records will be lost if something like a crash# happens this is the preferred way to run Redis. If instead you care a lot# about your data and don"t want to that a single record can get lost you should# enable the append only mode: when this mode is enabled Redis will append# every write operation received in the file appendonly.log. This file will# be read on startup in order to rebuild the full dataset in memory.## Note that you can have both the async dumps and the append only file if you# like （you have to comment the "save" statements above to disable the dumps）.# Still if append only mode is enabled Redis will load the data from the# log file at startup ignoring the dump.rdb file.## The name of the append only file is "appendonly.log"## IMPORTANT: Check the BGREWRITEAOF to check how to rewrite the append# log file in background when it gets too big. appendonly no # The fsync（） call tells the Operating System to actually write data on disk# instead to wait 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 if one second passed since the last fsync. Compromise.## The default is "always" that"s the safer of the options. It"s up to you to# understand if you can relax this to "everysec" that will fsync every second# or to "no" that will let the operating system flush the output buffer when# it want, for better performances （but if you can live with the idea of# some data loss consider the default persistence mode that"s snapshotting）. appendfsync always# appendfsync everysec# appendfsync no ############################### ADVANCED CONFIG ############################### # Glue small output buffers together in order to send small replies in a# single TCP packet. Uses a bit more CPU but most of the times it is a win# in terms of number of queries per second. Use "yes" if unsure.glueoutputbuf yes # Use object sharing. Can save a lot of memory if you have many common# string in your dataset, but performs lookups against the shared objects# pool so it uses more CPU and can be a bit slower. Usually it"s a good# idea.## When object sharing is enabled （shareobjects yes） you can use# shareobjectspoolsize to control the size of the pool used in order to try# object sharing. A bigger pool size will lead to better sharing capabilities.# In general you want this value to be at least the double of the number of# very common strings you have in your dataset.## WARNING: object sharing is experimental, don"t enable this feature# in production before of Redis 1.0-stable. Still please try this feature in# your development environment so that we can test it better.# shareobjects no# shareobjectspoolsize 1024Ubuntu 14.04下Redis安装及简单测试 http://www.linuxidc.com/Linux/2014-05/101544.htmRedis集群明细文档 http://www.linuxidc.com/Linux/2013-09/90118.htmUbuntu 12.10下安装Redis（图文详解）+ Jedis连接Redis http://www.linuxidc.com/Linux/2013-06/85816.htmRedis系列-安装部署维护篇 http://www.linuxidc.com/Linux/2012-12/75627.htmCentOS 6.3安装Redis http://www.linuxidc.com/Linux/2012-12/75314.htmRedis安装部署学习笔记 http://www.linuxidc.com/Linux/2014-07/104306.htmRedis配置文件redis.conf 详解 http://www.linuxidc.com/Linux/2013-11/92524.htmRedis 的详细介绍：请点这里
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