June 18 2015

redis学习(3)

3. Redis配置
•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 no
•2. 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.pid
•3. 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 6379
•4. 绑定的主机地址
•    bind 127.0.0.1
•5.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 300
•6. 指定日志记录级别,Redis总共支持四个级别:debug、verbose、notice、warning,默认为verbose

loglevel verbose

•7. 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/null
•    logfile stdout
•8. 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id
•    databases 16
•9. 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 1
•    save 300 10
•    save 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 yes
•11. 指定本地数据库文件名,默认值为dump.rdb
•    dbfilename dump.rdb
•12. 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 foobared
•16. 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 128
•17. 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no
•    appendonly no
•19. 指定更新日志文件名,默认为appendonly.aof
•     appendfilename appendonly.aof
•20. 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 no
•22. 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.swap
•23. 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0
•     vm-max-memory 0
•24. 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 32
•25. 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 134217728
•26. 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4
•     vm-max-threads 4
•27. 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 yes
•28. 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 64
•    hash-max-zipmap-value 512
•29. 指定是否激活重置哈希,默认为开启
•    activerehashing yes
•30. 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

[root@ucjmh etc]# cat redis.conf

# Redis configuration file example

# 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

################################ 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

# When running daemonized, Redis writes 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 6379.

# If port 0 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

# By default Redis listens for connections from all the network interfaces

# available on the server. It is possible to listen to just one or multiple

# 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

# 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 60 seconds.

tcp-keepalive 0

# 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 “”

# 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 <dbid> where

# dbid is a number between 0 and ‘databases’-1

databases 16

################################ SNAPSHOTTING  ################################

#

# 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 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 ./

################################# 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 <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>

# 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 <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).

#

# 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 <bytes>

# 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-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 multiple of the node timeout.

#

# cluster-node-timeout 15000

# 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 <milliseconds>” 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@<db>__ prefix.

#  E     Keyevent events, published with __keyevent@<db>__ 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

# Similarly to hashes, small lists are also encoded in a special way in order

# to save a lot of space. The special representation is only used when

# you are under the following limits:

list-max-ziplist-entries 512

list-max-ziplist-value 64

# 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 <class> <hard limit> <soft limit> <soft seconds>

#

# 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

[root@ucjmh etc]#



Copyright 2019. All rights reserved.

Posted 2015年6月18日 by ucjmh in category "redis

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