redis配置文件redis.conf参数说明 (-01-09 21:20:40)转载▼标签： redis配置 redis.conf 配置说明 杂谈 分类： nosql# 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.#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 no# When running daemonized, Redis writes a pid file in /var/run/redis.pid by# default. You can specify a custom pid file location here.#当 Redis 以守护进程的方式运行的时候，Redis 默认会把 pid 文件放在/var/run/redis.pid#可配置到其他地址，当运行多个 redis 服务时，需要指定不同的 pid 文件和端口pidfile /var/run/redis.pid# Accept connections on the specified port, default is 6379.# If port 0 is specified Redis will not listen on a TCP socket.#端口port 6379# If you want you can bind a single interface, if the bind option is not# specified all the interfaces will listen for incoming connections.#指定Redis可接收请求的IP地址,不设置将处理所有请求,建议生产环境中设置# bind 127.0.0.1# Close the connection after a client is idle for N seconds (0 to disable)#客户端连接的超时时间,单位为秒,超时后会关闭连接timeout 0# Set server verbosity to 'debug'# it 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)#日志记录等级，4个可选值loglevel notice# Specify the log file name. Also 'stdout' 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#配置 log 文件地址,默认打印在命令行终端的窗口上，也可设为/dev/null屏蔽日志、logfile 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 where# dbid is a number between 0 and 'databases'-1#设置数据库的个数,可以使用 SELECT 命令来切换数据库。databases 16## 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 at all commenting all the "save" lines.#设置 Redis 进行数据库镜像的频率。保存数据到disk的策略#900秒之内有1个keys发生变化时#30秒之内有10个keys发生变化时#60秒之内有10000个keys发生变化时save 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.#在进行镜像备份时,是否进行压缩rdbcompression yes# The filename where to dump the DB#镜像备份文件的文件名dbfilename dump.rdb# The working directory.## The DB will be written inside this directory, with the filename specified# above using the 'dbfilename' configuration directive.# # Also the Append Only File will be created inside this directory.# # Note that you must specify a directory here, not a file name.#数据库镜像备份的文件放置的路径#路径跟文件名分开配置是因为 Redis 备份时，先会将当前数据库的状态写入到一个临时文件#等备份完成时，再把该临时文件替换为上面所指定的文件#而临时文件和上面所配置的备份文件都会放在这个指定的路径当中#默认值为 ./dir /var/lib/redis/# 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.#设置该数据库为其他数据库的从数据库#slaveof <masterip> <masterport> 当本机为从服务时，设置主服务的IP及端口# 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.#指定与主数据库连接时需要的密码验证#masterauth <master-password> 当本机为从服务时，设置主服务的连接密码# masterauth# When a slave lost the 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 data 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.#当slave丢失与master的连接时，或slave仍然在于master进行数据同步时（未与master保持一致）#slave可有两种方式来响应客户端请求：#1)如果 slave-serve-stale-data 设置成 'yes'(默认)，slave仍会响应客户端请求,此时可能会有问题#2)如果 slave-serve-stale-data 设置成 'no'，slave会返回"SYNC with master in progress"错误信息，但 INFO 和SLAVEOF命令除外。slave-serve-stale-data yes# 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.#设置客户端连接后进行任何其他指定前需要使用的密码#redis速度相当快，一个外部用户在一秒钟进行150K次密码尝试，需指定强大的密码来防止暴力破解# requirepass foobared# 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 limits.# Once the limit is reached Redis will close all the new connections sending# an error 'max number of clients reached'.#限制同时连接的客户数量。#当连接数超过这个值时，redis 将不再接收其他连接请求，客户端尝试连接时将收到 error 信息# 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# accordingly to the eviction policy selected (see maxmemmory-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# an 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').#设置redis能够使用的最大内存。#达到最大内存设置后，Redis会先尝试清除已到期或即将到期的Key（设置过expire信息的key）#在删除时,按照过期时间进行删除，最早将要被过期的key将最先被删除#如果已到期或即将到期的key删光，仍进行set操作，那么将返回错误#此时redis将不再接收写请求,只接收get请求。#maxmemory的设置比较适合于把redis当作于类似memcached 的缓存来使用# maxmemory <bytes># By default Redis asynchronously 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.aof. 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.## IMPORTANT: Check the BGREWRITEAOF to check how to rewrite the append# log file in background when it gets too big.#redis 默认每次更新操作后会在后台异步的把数据库镜像备份到磁盘，但该备份非常耗时，且备份不宜太频繁#redis 同步数据文件是按上面save条件来同步的#如果发生诸如拉闸限电、拔插头等状况,那么将造成比较大范围的数据丢失#所以redis提供了另外一种更加高效的数据库备份及灾难恢复方式#开启append only 模式后,redis 将每一次写操作请求都追加到appendonly.aof 文件中#redis重新启动时,会从该文件恢复出之前的状态。#但可能会造成 appendonly.aof 文件过大，所以redis支持BGREWRITEAOF 指令，对appendonly.aof重新整理appendonly no# The name of the append only file (default: "appendonly.aof")##更新日志文件名，默认值为appendonly.aof# appendfilename appendonly.aof# 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 "everysec" 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 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.## If unsure, use "everysec".#设置对 appendonly.aof 文件进行同步的频率#always 表示每次有写操作都进行同步,everysec 表示对写操作进行累积,每秒同步一次。#no表示等操作系统进行数据缓存同步到磁盘，都进行同步,everysec 表示对写操作进行累积,每秒同步一次# appendfsync alwaysappendfsync everysec# appendfsync no# Virtual Memory allows Redis to work with datasets bigger than the actual# amount of RAM needed to hold the whole dataset in memory.# In order to do so very used keys are taken in memory while the other keys# are swapped into a swap file, similarly to what operating systems do# with memory pages.## To enable VM just set 'vm-enabled' to yes, and set the following three# VM parameters accordingly to your needs.#是否开启虚拟内存支持。#redis 是一个内存数据库，当内存满时,无法接收新的写请求,所以在redis2.0后,提供了虚拟内存的支持#但需要注意的，redis 所有的key都会放在内存中，在内存不够时,只把value 值放入交换区#虽使用虚拟内存，但性能基本不受影响，需要注意的是要把vm-max-memory设置到足够来放下所有的keyvm-enabled no# vm-enabled yes# This is the path of the Redis swap file. As you can guess, swap files# can't be shared by different Redis instances, so make sure to use a swap# file for every redis process you are running. Redis will complain if the# swap file is already in use.## The best kind of storage for the Redis swap file (that's accessed at random) # is a Solid State Disk (SSD).## *** WARNING *** if you are using a shared hosting the default of putting# the swap file under /tmp is not secure. Create a dir with access granted# only to Redis user and configure Redis to create the swap file there.#设置虚拟内存的交换文件路径，不可多个Redis实例共享vm-swap-file /tmp/redis.swap# vm-max-memory configures the VM to use at max the specified amount of# RAM. Everything that deos not fit will be swapped on disk *if* possible, that# is, if there is still enough contiguous space in the swap file.## With vm-max-memory 0 the system will swap everything it can. Not a good# default, just specify the max amount of RAM you can in bytes, but it's# better to leave some margin. For instance specify an amount of RAM# that's more or less between 60 and 80% of your free RAM.#设置开启虚拟内存后,redis将使用的最大物理内存大小。#默认为0，redis将把他所有能放到交换文件的都放到交换文件中，以尽量少的使用物理内存#即当vm-max-memory设置为0的时候,其实是所有value都存在于磁盘#在生产环境下,需要根据实际情况设置该值,最好不要使用默认的 0vm-max-memory 0# Redis swap files is split into pages. An object can be saved using multiple# contiguous pages, but pages can't be shared between different objects.# So if your page is too big, small objects swapped out on disk will waste# a lot of space. If you page is too small, there is less space in the swap# file (assuming you configured the same number of total swap file pages).## If you use a lot of small objects, use a page size of 64 or 32 bytes.# If you use a lot of big objects, use a bigger page size.# If unsure, use the default :)#设置虚拟内存的页大小如果 value 值比较大,如要在 value 中放置博客、新闻之类的所有文章内容，就设大一点vm-page-size 32# Number of total memory pages in the swap file.# Given that the page table (a bitmap of free/used pages) is taken in memory,# every 8 pages on disk will consume 1 byte of RAM.## The total swap size is vm-page-size * vm-pages## With the default of 32-bytes memory pages and 134217728 pages Redis will# use a 4 GB swap file, that will use 16 MB of RAM for the page table.## It's better to use the smallest acceptable value for your application,# but the default is large in order to work in most conditions.#设置交换文件的总的 page 数量#注意page table信息是放在物理内存中，每8个page 就会占据RAM中的 1 个 byte#总的虚拟内存大小 = vm-page-size * vm-pagesvm-pages 134217728# Max number of VM I/O threads running at the same time.# This threads are used to read/write data from/to swap file, since they# also encode and decode objects from disk to memory or the reverse, a bigger# number of threads can help with big objects even if they can't help with# I/O itself as the physical device may not be able to couple with many# reads/writes operations at the same time.## The special value of 0 turn off threaded I/O and enables the blocking# Virtual Memory implementation.#设置 VM IO 同时使用的线程数量。vm-max-threads 4# Hashes are encoded in a special way (much more memory efficient) when they# have at max a given numer of elements, and the biggest element does not# exceed a given threshold. You can configure this limits with the following# configuration directives.#redis 2.0后引入了 hash 数据结构。 #hash 中包含超过指定元素个数并且最大的元素当没有超过临界时，hash 将以zipmap来存储#zipmap又称为 small hash，可大大减少内存的使用hash-max-zipmap-entries 512hash-max-zipmap-value 64# 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 an hash table# that is rhashing, 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# active rehashing 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 form 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.#是否重置Hash表#设置成yes后redis将每100毫秒使用1毫秒CPU时间来对redis的hash表重新hash，可降低内存的使用#当使用场景有较为严格的实时性需求,不能接受Redis时不时的对请求有2毫秒的延迟的话，把这项配置为no。#如果没有这么严格的实时性要求,可以设置为 yes,以便能够尽可能快的释放内存activerehashing yesRedis官方文档对VM的使用提出了一些建议:当key很小而value很大时,使用VM的效果会比较好.因为这样节约的内存比较大当key不小时,可以考虑使用一些非常方法将很大的key变成很大的value,如可将key,value组合成一个新的value最好使用linux ext3 等对稀疏文件支持比较好的文件系统保存你的swap文件vm-max-threads参数可设置访问swap文件的线程数，最好不要超过机器的核数；设置为0则所有对swap文件的操作都是串行的，可能会造成比较长时间的延迟,但是对数据完整性有很好的保证redis数据存储redis的存储分为内存存储、磁盘存储和log文件三部分，配置文件中有三个参数对其进行配置。save seconds updates，save配置，指出在多长时间内，有多少次更新操作，就将数据同步到数据文件。可多个条件配合，默认配置了三个条件。appendonly yes/no ，appendonly配置，指出是否在每次更新操作后进行日志记录，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的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。appendfsync no/always/everysec ，appendfsync配置，no表示等操作系统进行数据缓存同步到磁盘，always表示每次更新操作后手动调用fsync()将数据写到磁盘，everysec表示每秒同步一次。
