解析Redis配置檔案redis.conf

簡單介紹

units機關

• 配置大小機關,開頭定義了一些基本的度量機關，隻支援bytes，不支援bit
• 對大小寫不敏感

INCLUDES包含

• 和我們的Struts2配置檔案類似，可以通過includes包含，redis.conf可以作為總閘，包含其他

GENERAL通用

• daemonize
• pidfile
• port
• tcp-backlog：

設定tcp的backlog，backlog其實是一個連接配接隊列，backlog隊列總和=未完成三次握手隊列 + 已經完成三次握手隊列。 在高并發環境下你需要一個高backlog值來避免慢用戶端連接配接問題。注意Linux核心會将這個值減小到/proc/sys/net/core/somaxconn的值，是以需要确認增大somaxconn和tcp_max_syn_backlog兩個值來達到想要的效果

• timeout
• bind
• tcp-keepalive：機關為秒，如果設定為0，則不會進行Keepalive檢測，建議設定成60 
• loglevel
• logfile
• syslog-enabled：是否把日志輸出到syslog中
• syslog-ident：指定syslog裡的日志标志
• syslog-facility：指定syslog裝置，值可以是USER或LOCAL0-LOCAL7
• databases

SNAPSHOTTING快照

• Save
• save 秒鐘 寫操作次數

RDB是整個記憶體的壓縮過的Snapshot，RDB的資料結構，可以配置複合的快照觸發條件， 預設 是1分鐘内改了1萬次， 或5分鐘内改了10次， 或15分鐘内改了1次。

• 禁用 如果想禁用RDB持久化的政策，隻要不設定任何save指令，或者給save傳入一個空字元串參數也可以save ""

想要馬上備份的話，在操作後輸入 save 指令 就會直接備份到dump.rdb檔案中

• stop-writes-on-bgsave-error：如果配置成no，表示你不在乎資料不一緻或者有其他的手段發現和控制

• rdbcompression：對于存儲到磁盤中的快照，可以設定是否進行壓縮存儲。如果是的話，redis會采用LZF算法進行壓縮。如果你不想消耗CPU來進行壓縮的話，可以設定為關閉此功能
• rdbchecksum：在存儲快照後，還可以讓redis使用CRC64算法來進行資料校驗，但是這樣做會增加大約10%的性能消耗，如果希望擷取到最大的性能提升，可以關閉此功能
• dbfilename
• dir：本地資料庫存放目錄

REPLICATION複制 SECURITY安全 通路密碼的檢視、設定和取消 LIMITS限制

• maxclients：設定redis同時可以與多少個用戶端進行連接配接。預設情況下為10000個用戶端。當你無法設定程序檔案句柄限制時，redis會設定為目前的檔案句柄限制值減去32，因為redis會為自身内部處理邏輯留一些句柄出來。如果達到了此限制，redis則會拒絕新的連接配接請求，并且向這些連接配接請求方發出“max number of clients reached”以作回應。
• maxmemory：設定redis可以使用的記憶體量。一旦到達記憶體使用上限，redis将會試圖移除内部資料，移除規則可以通過maxmemory-policy來指定。如果redis無法根據移除規則來移除記憶體中的資料，或者設定了“不允許移除”，那麼redis則會針對那些需要申請記憶體的指令傳回錯誤資訊，比如SET、LPUSH等。

但是對于無記憶體申請的指令，仍然會正常響應，比如GET等。如果你的redis是主redis（說明你的redis有從redis），那麼在設定記憶體使用上限時，需要在系統中留出一些記憶體空間給同步隊列緩存，隻有在你設定的是“不移除”的情況下，才不用考慮這個因素

• maxmemory-policy：

1. volatile-lru -> remove the key with an expire set using an LRU algorithm 使用LRU算法移除key，隻對設定了過期時間的鍵
2. allkeys-lru -> remove any key according to the LRU algorithm 使用LRU算法移除key
3. volatile-random -> remove a random key with an expire set 在過期集合中移除随機的key，隻對設定了過期時間的鍵
4. allkeys-random -> remove a random key, any key 移除随機的key
5. volatile-ttl -> remove the key with the nearest expire time (minor TTL) 移除那些TTL值最小的key，即那些最近要過期的key
6. noeviction -> don't expire at all, just return an error on write operations 不進行移除。針對寫操作，隻是傳回錯誤資訊

• maxmemory-samples：設定樣本數量，LRU算法和最小TTL算法都并非是精确的算法，而是估算值，是以你可以設定樣本的大小，redis預設會檢查這麼多個key并選擇其中LRU的那個

APPEND ONLY MODE追加

• appendonly
• appendfilename
• appendfsync：

1. always：同步持久化 每次發生資料變更會被立即記錄到磁盤 性能較差但資料完整性比較好
2. everysec：出廠預設推薦，異步操作，每秒記錄 如果一秒内當機，有資料丢失
3. no

• no-appendfsync-on-rewrite：重寫時是否可以運用Appendfsync，用預設no即可，保證資料安全性。
• auto-aof-rewrite-min-size：設定重寫的基準值
• auto-aof-rewrite-percentage：設定重寫的基準值

常見配置redis.conf介紹 參數說明 redis.conf 配置項說明如下： 1. Redis預設不是以守護程序的方式運作，可以通過該配置項修改，使用yes啟用守護程序   daemonize no 2. 當Redis以守護程序方式運作時，Redis預設會把pid寫入/var/run/redis.pid檔案，可以通過pidfile指定   pidfile /var/run/redis.pid 3. 指定Redis監聽端口，預設端口為6379，作者在自己的一篇博文中解釋了為什麼選用6379作為預設端口，因為6379在手機按鍵上MERZ對應的号碼，而MERZ取自意大利歌女Alessia Merz的名字   port 6379 4. 綁定的主機位址   bind 127.0.0.1 5.當 用戶端閑置多長時間後關閉連接配接，如果指定為0，表示關閉該功能   timeout 300 6. 指定日志記錄級别，Redis總共支援四個級别：debug、verbose、notice、warning，預設為verbose   loglevel verbose 7. 日志記錄方式，預設為标準輸出，如果配置Redis為守護程序方式運作，而這裡又配置為日志記錄方式為标準輸出，則日志将會發送給/dev/null   logfile stdout 8. 設定資料庫的數量，預設資料庫為0，可以使用SELECT <dbid>指令在連接配接上指定資料庫id   databases 16 9. 指定在多長時間内，有多少次更新操作，就将資料同步到資料檔案，可以多個條件配合  save <seconds> <changes>   Redis預設配置檔案中提供了三個條件：   save 900 1   save 300 10   save 60 10000   分别表示900秒（15分鐘）内有1個更改，300秒（5分鐘）内有10個更改以及60秒内有10000個更改。   10. 指定存儲至本地資料庫時是否壓縮資料，預設為yes，Redis采用LZF壓縮，如果為了節省CPU時間，可以關閉該選項，但會導緻資料庫檔案變的巨大   rdbcompression yes 11. 指定本地資料庫檔案名，預設值為dump.rdb   dbfilename dump.rdb 12. 指定本地資料庫存放目錄   dir ./ 13. 設定當本機為slav服務時，設定master服務的IP位址及端口，在Redis啟動時，它會自動從master進行資料同步   slaveof <masterip> <masterport> 14. 當master服務設定了密碼保護時，slav服務連接配接master的密碼   masterauth <master-password> 15. 設定Redis連接配接密碼，如果配置了連接配接密碼，用戶端在連接配接Redis時需要通過AUTH <password>指令提供密碼，預設關閉   requirepass foobared 16. 設定同一時間最大用戶端連接配接數，預設無限制，Redis可以同時打開的用戶端連接配接數為Redis程序可以打開的最大檔案描述符數，如果設定 maxclients 0，表示不作限制。當用戶端連接配接數到達限制時，Redis會關閉新的連接配接并向用戶端傳回max number of clients reached錯誤資訊   maxclients 128 17. 指定Redis最大記憶體限制，Redis在啟動時會把資料加載到記憶體中，達到最大記憶體後，Redis會先嘗試清除已到期或即将到期的Key，當此方法處理 後，仍然到達最大記憶體設定，将無法再進行寫入操作，但仍然可以進行讀取操作。Redis新的vm機制，會把Key存放記憶體，Value會存放在swap區   maxmemory <bytes> 18. 指定是否在每次更新操作後進行日志記錄，Redis在預設情況下是異步的把資料寫入磁盤，如果不開啟，可能會在斷電時導緻一段時間内的資料丢失。因為 redis本身同步資料檔案是按上面save條件來同步的，是以有的資料會在一段時間内隻存在于記憶體中。預設為no   appendonly no 19. 指定更新日志檔案名，預設為appendonly.aof    appendfilename appendonly.aof 20. 指定更新日志條件，共有3個可選值：    no：表示等作業系統進行資料緩存同步到磁盤（快）    always：表示每次更新操作後手動調用fsync()将資料寫到磁盤（慢，安全）    everysec：表示每秒同步一次（折衷，預設值）   appendfsync everysec   21. 指定是否啟用虛拟記憶體機制，預設值為no，簡單的介紹一下，VM機制将資料分頁存放，由Redis将通路量較少的頁即冷資料swap到磁盤上，通路多的頁面由磁盤自動換出到記憶體中（在後面的文章我會仔細分析Redis的VM機制）    vm-enabled no 22. 虛拟記憶體檔案路徑，預設值為/tmp/redis.swap，不可多個Redis執行個體共享    vm-swap-file /tmp/redis.swap 23. 将所有大于vm-max-memory的資料存入虛拟記憶體,無論vm-max-memory設定多小,所有索引資料都是記憶體存儲的(Redis的索引資料 就是keys),也就是說,當vm-max-memory設定為0的時候,其實是所有value都存在于磁盤。預設值為0    vm-max-memory 0 24. Redis swap檔案分成了很多的page，一個對象可以儲存在多個page上面，但一個page上不能被多個對象共享，vm-page-size是要根據存儲的 資料大小來設定的，作者建議如果存儲很多小對象，page大小最好設定為32或者64bytes；如果存儲很大大對象，則可以使用更大的page，如果不 确定，就使用預設值    vm-page-size 32 25. 設定swap檔案中的page數量，由于頁表（一種表示頁面空閑或使用的bitmap）是在放在記憶體中的，，在磁盤上每8個pages将消耗1byte的記憶體。    vm-pages 134217728 26. 設定通路swap檔案的線程數,最好不要超過機器的核數,如果設定為0,那麼所有對swap檔案的操作都是串行的，可能會造成比較長時間的延遲。預設值為4    vm-max-threads 4 27. 設定在向用戶端應答時，是否把較小的包合并為一個包發送，預設為開啟   glueoutputbuf yes 28. 指定在超過一定的數量或者最大的元素超過某一臨界值時，采用一種特殊的雜湊演算法   hash-max-zipmap-entries 64   hash-max-zipmap-value 512 29. 指定是否激活重置哈希，預設為開啟（後面在介紹Redis的雜湊演算法時具體介紹）   activerehashing yes 30. 指定包含其它的配置檔案，可以在同一主機上多個Redis執行個體之間使用同一份配置檔案，而同時各個執行個體又擁有自己的特定配置檔案   include /path/to/local.conf

———————————————— 配置檔案執行個體——————————————————————————

# Redis configuration file example

# Note on units: when memory size is needed, it is possible to specifiy
# it in the usual form of 1k 5GB 4M and so forth:
# 當你需要為某個配置項指定記憶體大小的時候，必須要帶上機關，# 通常的格式就是 1k 5gb 4m 等醬紫：
#
# 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.
# 機關是不區分大小寫的，1GB 1Gb 1gB是一樣的

# 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.
# 預設情況下 redis 不是作為守護程序運作的，如果你想讓它在背景運作，你就把它改成 yes。# 當redis作為守護程序運作的時候，它會寫一個 pid 到 /var/run/redis.pid 檔案裡面。
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.
# 當redis作為守護程序運作的時候，它會把 pid 預設寫到 /var/run/redis.pid 檔案裡面，# 但是你可以在這裡自己制定它的檔案位置。
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.
# 監聽端口号，預設為 6379，如果你設為 0 ，redis 将不在 socket 上監聽任何用戶端連接配接。
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.
#
# 預設情況下，redis 在 server 上所有有效的網絡接口上監聽用戶端連接配接。# 你如果隻想讓它在一個網絡接口上監聽，那你就綁定一個IP或者多個IP。## 示例，多個IP用空格隔開:# 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.
# 指定 unix socket 的路徑。
# unixsocket /tmp/redis.sock
# unixsocketperm 755

# Close the connection after a client is idle for N seconds (0 to disable)
# 指定在一個 client 空閑多少秒之後關閉連接配接（0 就是不管它）
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)
# 定義日志級别。# 可以是下面的這些值：# debug (适用于開發或測試階段)# verbose (many rarely useful info, but not a mess like the debug level)# notice (适用于生産環境)# warning (僅僅一些重要的消息被記錄)
loglevel verbose

# 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
# 指定日志檔案的位置
logfile stdout

# To enable logging to the system logger, just set 'syslog-enabled' to yes,
# and optionally update the other syslog parameters to suit your needs.
# 要想把日志記錄到系統日志，就把它改成 yes，# 也可以可選擇性的更新其他的syslog 參數以達到你的要求
# syslog-enabled no

# Specify the syslog identity.
設定 syslog 的 identity。
# syslog-ident redis

# Specify the syslog facility.  Must be USER or between LOCAL0-LOCAL7.
# 設定 syslog 的 facility，必須是 USER 或者是 LOCAL0-LOCAL7 之間的值
# 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
# 設定資料庫的數目。# 預設資料庫是 DB 0，你可以在每個連接配接上使用 select <dbid> 指令選擇一個不同的資料庫，# 但是 dbid 必須是一個介于 0 到 databasees - 1 之間的值
databases 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 changed
#   下面的例子的意思是：#   900 秒内如果至少有 1 個 key 的值變化，則儲存#   300 秒内如果至少有 10 個 key 的值變化，則儲存#   60 秒内如果至少有 10000 個 key 的值變化，則儲存
#
#   Note: you can disable saving at all commenting all the "save" lines.
#   注意：你可以注釋掉所有的 save 行來停用儲存功能。#   也可以直接一個空字元串來實作停用：#   save ""
save 900 1
save 300 10
save 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.
# 是否在 dump .rdb 資料庫的時候使用 LZF 壓縮字元串# 預設都設為 yes# 如果你希望儲存子程序節省點 cpu ，你就設定它為 no ，# 不過這個資料集可能就會比較大
rdbcompression yes

# The filename where to dump the DB
# 設定 dump 的檔案位置
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.
# 工作目錄# 例如上面的 dbfilename 隻指定了檔案名，# 但是它會寫入到這個目錄下。這個配置項一定是個目錄，而不能是檔案名
dir ./

################################# REPLICATION  主從複制#################################

# 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.
# 主從複制。使用 slaveof 來讓一個 redis 執行個體成為另一個reids 執行個體的副本。# 注意這個隻需要在 slave 上配置。
# 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.
# 如果 master 需要密碼認證，就在這裡設定
# masterauth <master-password>

# 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.
# 當一個 slave 與 master 失去聯系，或者複制正在進行的時候，# slave 可能會有兩種表現：## 1) 如果為 yes ，slave 仍然會應答用戶端請求，但傳回的資料可能是過時，#    或者資料可能是空的在第一次同步的時候## 2) 如果為 no ，在你執行除了 info he salveof 之外的其他指令時，#    slave 都将傳回一個 "SYNC with master in progress" 的錯誤，
slave-serve-stale-data yes

# 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 a timeout for both Bulk transfer I/O timeout and
# master data or ping response timeout. The default value is 60 seconds.
#
# 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.
# 設定主從複制過期時間
# repl-timeout 60

################################## SECURITY  安全 ###################################

# 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.
# 設定認證密碼
# requirepass foobared

# Command renaming.
#
# It is possilbe to change the name of dangerous commands in a shared
# environment. For instance the CONFIG command may be renamed into something
# of hard to guess so that it will be still available for internal-use
# tools but not available for general clients.
#
# Example:
#
# rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
#
# It is also possilbe to completely kill a command renaming it into
# an empty string:
#
# rename-command CONFIG ""

################################### LIMITS  限制 ####################################

# 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'.
# 一旦達到最大限制，redis 将關閉所有的新連接配接# 并發送一個‘max number of clients reached’的錯誤。
# 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.
# 最大使用記憶體
# maxmemory <bytes>

# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
# is reached? You can select among five behavior:
# 
# volatile-lru -> remove the key with an expire set using an LRU algorithm
# allkeys-lru -> remove any key accordingly 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 all the kind of policies, Redis will return an error on write
#       operations, when there are not suitable keys for eviction.
#
#       At the date of writing this 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 volatile-lru

# LRU and minimal TTL algorithms are not precise algorithms but approximated
# algorithms (in order to save memory), so you can select as well the sample
# size to check. For instance for default Redis will check three keys and
# pick the one that was used less recently, you can change the sample size
# using the following configuration directive.
#
# maxmemory-samples 3

############################## APPEND ONLY MODE ###############################

# 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.

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 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".

# 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", that in pratical terms means that it is
# possible to lost 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 will growth by the specified percentage.
# 
# This is how it works: Redis remembers the size of the AOF file after the
# latest rewrite (or if no rewrite 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 precentage of zero in order to disable the automatic AOF
# rewrite feature.

auto-aof-rewrite-percentage 100
auto-aof-rewrite-min-size 64mb

################################## 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 1024

################################ VIRTUAL MEMORY ###############################

### WARNING! Virtual Memory is deprecated in Redis 2.4
### The use of Virtual Memory is strongly discouraged.

### WARNING! Virtual Memory is deprecated in Redis 2.4
### The use of Virtual Memory is strongly discouraged.

# 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.

vm-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.
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.
vm-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 :)
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.
vm-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.
vm-max-threads 4

############################### ADVANCED CONFIG ###############################

# 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.
hash-max-zipmap-entries 512
hash-max-zipmap-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 happens 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

# 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.
activerehashing yes

################################## INCLUDES ###################################

# Include one or more other config files here.  This is useful if you
# have a standard template that goes to all redis server but also need
# to customize a few per-server settings.  Include files can include
# other files, so use this wisely.
# 假如說你有一個可用于所有的 redis server 的标準配置模闆，# 但針對某些 server 又需要一些個性化的設定，# 你可以使用 include 來包含一些其他的配置檔案，這對你來說是非常有用的。## 但是要注意哦，include 是不能被 config rewrite 指令改寫的# 由于 redis 總是以最後的加工線作為一個配置指令值，是以你最好是把 include 放在這個檔案的最前面，# 以避免在運作時覆寫配置的改變，相反，你就把它放在後面（外國人真啰嗦）。
# include /path/to/local.conf
# include /path/to/other.conf
           

參考： 尚矽谷周陽老師資料 http://www.cnblogs.com/kreo/p/4423362.html