Redis持久化

appendonly no  # 默认是关闭AOF的
appendfilename "appendonly.aof" # 文件名称，也会存储在跟RDB一样的目录下

# 三个级别
# appendfsync always 
appendfsync everysec # 每秒
# appendfsync no

no-appendfsync-on-rewrite no 
#yes: 如果redis抛出一个子进程在处理进行rdb或者aof的重写(bgrewriteaof)的时候，那么父进程不论哪个级别都不会把缓冲区的数据刷写到磁盘，因为子进程正在对着磁盘做写操作，减少争抢I/O，但是容易丢数据
# no：不会丢失数据，但是要忍受阻塞的问题

aof-use-rdb-preamble yes # 重写时，先将老的数据RDB,写到AOF文件中，再将增量的以指令的方式Append到AOF中

[root@hadoop01 6379]# redis-server /etc/redis/6379.conf 
1835:C 26 Mar 2021 16:46:13.276 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
1835:C 26 Mar 2021 16:46:13.276 # Redis version=6.0.0, bits=64, commit=00000000, modified=0, pid=1835, just started
1835:C 26 Mar 2021 16:46:13.276 # Configuration loaded
1835:M 26 Mar 2021 16:46:13.281 * Increased maximum number of open files to 10032 (it was originally set to 1024).
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      _.-``    `.  `_.  ''-._           Redis 6.0.0 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._                                   
 (    '      ,       .-`  | `,    )     Running in standalone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
 |    `-._   `._    /     _.-'    |     PID: 1835
  `-._    `-._  `-./  _.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |           http://redis.io        
  `-._    `-._`-.__.-'_.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |                                  
  `-._    `-._`-.__.-'_.-'    _.-'                                   
      `-._    `-.__.-'    _.-'                                       
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1835:M 26 Mar 2021 16:46:13.286 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
1835:M 26 Mar 2021 16:46:13.286 # Server initialized
1835:M 26 Mar 2021 16:46:13.286 # 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.
1835:M 26 Mar 2021 16:46:13.286 # 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.
1835:M 26 Mar 2021 16:46:13.287 * Ready to accept connections

[root@hadoop01 6379]# pwd
/var/lib/redis/6379
[root@hadoop01 6379]# ll
总用量 0
-rw-r--r-- 1 root root 0 3月  26 16:46 appendonly.aof
[root@hadoop01 6379]# 

[root@hadoop01 6379]# redis-cli 
127.0.0.1:6379> set k1 hello
OK
127.0.0.1:6379> 

[root@hadoop01 6379]# redis-cli 
127.0.0.1:6379> set k1 hello
OK
127.0.0.1:6379> bgsave
Background saving started
127.0.0.1:6379> 

...
1835:M 26 Mar 2021 16:46:13.287 * Ready to accept connections
1835:M 26 Mar 2021 16:56:50.778 * Background saving started by pid 1967 # 开辟了一个子进程
1967:C 26 Mar 2021 16:56:50.787 * DB saved on disk
1967:C 26 Mar 2021 16:56:50.791 * RDB: 4 MB of memory used by copy-on-write # 写时复制完成
1835:M 26 Mar 2021 16:56:50.827 * Background saving terminated with success

[root@hadoop01 6379]# redis-check-rdb dump.rdb
[offset 0] Checking RDB file dump.rdb
[offset 26] AUX FIELD redis-ver = '6.0.0'
[offset 40] AUX FIELD redis-bits = '64'
[offset 52] AUX FIELD ctime = '1616749010'
[offset 67] AUX FIELD used-mem = '865048'
[offset 83] AUX FIELD aof-preamble = '0'
[offset 85] Selecting DB ID 0
--- RDB ERROR DETECTED ---
[offset 107] RDB CRC error
[additional info] While doing: check-sum
[info] 1 keys read
[info] 0 expires
[info] 0 already expired
[root@hadoop01 6379]# 

127.0.0.1:6379> set k1 1
OK
127.0.0.1:6379> set k1 2
OK
127.0.0.1:6379> set k1 3
OK
127.0.0.1:6379> set k1 a
OK
127.0.0.1:6379> set k1 b
OK
127.0.0.1:6379> set k1 c

[root@hadoop01 6379]# ll
总用量 8
-rw-r--r-- 1 root root 158 3月  26 17:09 appendonly.aof
-rw-r--r-- 1 root root 107 3月  26 16:56 dump.rdb
[root@hadoop01 6379]# 

127.0.0.1:6379> BGREWRITEAOF 
Background append only file rewriting started
127.0.0.1:6379> 

[root@hadoop01 6379]# redis-cli -p 6379  --raw
127.0.0.1:6379> set k1 aa
OK
127.0.0.1:6379> set k1 bb
OK
127.0.0.1:6379> set k1 cc
OK
127.0.0.1:6379> set k1 dd
OK
127.0.0.1:6379> 

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