Redis簡介

Redis 是一個開源（BSD 許可）、記憶體中資料結構儲存，用作資料庫、快取和訊息代理。它支援資料結構，如字串、雜湊、列表、集、帶範圍查詢的排序集、點陣圖、超日誌、具有半徑查詢的地理空間索引和流。Redis 具有內建複製、Lua 指令碼、LRU 逐出、事務和不同級別的磁碟永續性，並且通過 Redis Sentinel 和 Redis 群集自動分割槽提供高可用性。（官網詳解）

Redis安裝

下載官網

[root@app1 ~]# wget http://download.redis.io/releases/redis-5.0.9.tar.gz
[root@app1 ~]# tar -zxvf redis-5.0.9.tar.gz
[root@app1 ~]# mv redis-5.0.9 /home/redis

[root@app1 ~]# cd /home/redis/
[root@app1 redis]# yum install -y gcc
make 或 make MALLOC=libc
 

啟動後日志報錯，處理方法：

16290:M 24 Sep 2020 09:57:18.316 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
###TCP backlog設定值511沒有成功，因為/proc/sys/net/core/somaxconn這個設定的是更小的128

16290:M 24 Sep 2020 09:57:18.316 # Server initialized
16290:M 24 Sep 2020 09:57:18.316 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
###overcommit_memory引數設定為0！在記憶體不足的情況下，後臺程式save可能失敗。建議在檔案 /etc/sysctl.conf 中將overcommit_memory修改為1

[root@app1 ~]# vim /etc/sysctl.conf
net.core.somaxconn=1024
vm.overcommit_memory=1
[root@app1 ~]# sysctl -p

16314:M 24 Sep 2020 09:58:44.540 # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
###你使用的是透明大頁，可能導致redis延遲和記憶體使用問題，執行 echo never > /sys/kernel/mm/transparent_hugepage/enabled 修復該問題

[root@app1 ~]# vim /etc/rc.local
echo never > /sys/kernel/mm/transparent_hugepage/enabled
[root@app1 ~]# source /etc/rc.local
 

重新啟動Redis：

3408:C 30 Sep 2020 12:47:00.818 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3408:C 30 Sep 2020 12:47:00.818 # Redis version=5.0.9, bits=64, commit=00000000, modified=0, pid=3408, just started
3408:C 30 Sep 2020 12:47:00.818 # Configuration loaded
3409:M 30 Sep 2020 12:47:00.820 * Increased maximum number of open files to 10032 (it was originally set to 1024).
                _._
           _.-``__ ''-._
      _.-``    `.  `_.  ''-._           Redis 5.0.9 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._
 (    '      ,       .-`  | `,    )     Running in standalone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 7000
 |    `-._   `._    /     _.-'    |     PID: 3409
  `-._    `-._  `-./  _.-'    _.-'
 |`-._`-._    `-.__.-'    _.-'_.-'|
 |    `-._`-._        _.-'_.-'    |           http://redis.io
  `-._    `-._`-.__.-'_.-'    _.-'
 |`-._`-._    `-.__.-'    _.-'_.-'|
 |    `-._`-._        _.-'_.-'    |
  `-._    `-._`-.__.-'_.-'    _.-'
      `-._    `-.__.-'    _.-'
          `-._        _.-'
              `-.__.-'

3409:M 30 Sep 2020 12:47:00.821 # Server initialized
3409:M 30 Sep 2020 12:47:00.821 * DB loaded from disk: 0.000 seconds
3409:M 30 Sep 2020 12:47:00.821 * Ready to accept connections
 

Redis配置檔案詳解

###開啟redis
[root@app1 src]# ./redis-server ../redis.conf
###關閉redis
[root@app1 src]# ./redis-cli -h 127.0.0.1 -p 6379 -a qwer shutdown

h：host p：port a：auth

Redis修改配置

修改配置檔案方法（在不重啟例項情況下）：修改日誌等級

Redis預設的設定為verbose，開發測試階段可以用debug，生產模式一般選用notice

• debug：會打印出很多資訊，適用於開發和測試階段
• verbose（冗長的）：包含很多不太有用的資訊
• notice：適用於生產模式
• warning : 警告資訊

10.224.192.209:7000> CONFIG GET loglevel
1) "loglevel"
2) "verbose"

10.224.192.209:7000> CONFIG SET loglevel notice
OK

10.224.192.209:7000> CONFIG GET loglevel
1) "loglevel"
2) "notice"