Learning notes on Redis installation and deployment

Learning notes on Redis installation and deployment
1 Overview

Currently, most NoSql databases are essentially key-value pairs, and Redis is no exception. As a cache database, Memcached has the following advantages:

(1) in terms of speed, Redis is faster than Memcached, which is obtained based on some Benchmarks test results. In terms of memory usage, Redis breaks through the physical memory limit and can use virtual memory;

(2) There are more data types than Memcached. Redis supports multiple data structures, such as List, Set, SortedSet, and HashMap;

(3) In terms of persistence, Memcached does not have a corresponding persistence mechanism. Redis adopts the combination of RDB snapshot and AOF log for persistence, which guarantees data persistence and security to a great extent, unlike Memcached, it's all gone after power failure.

Redis is a good alternative to Memcached.

MongoDB is a NoSql database suitable for storing and querying formatted documents. It can be used for massive data storage. After all, it is a hard disk database, it is not comparable to the Redis cache database. If there are so many discussions on the internet, I will not talk about it here. For details, refer to document 1.

Redis can also store data on hard disks and replicate data across nodes. It can also be used as a queue system. It is said that GitHub uses Redis as its infrastructure.

Install and test Redis in Ubuntu 14.04

Redis cluster details

Install Redis in Ubuntu 12.10 (graphic explanation) + Jedis to connect to Redis

Redis series-installation, deployment, and maintenance

Install Redis in CentOS 6.3

Redis. conf

2. installation and deployment

The latest official stable version is 2.8.6. We will take it as an example to perform the following operations and instructions.

2.1 Centos installation and deployment

The installation procedure is as follows:

(1gz copy the redis-2.8.6.tar.gz installation package to our specified directory;

(2) Use the command tar-zxvf redis-2.8.6.tar.gz to decompress the tar package to get the redis-2.8.6 directory;

(3) enter the redis-2.8.6 directory, execute make command for compilation;

(4) After compilation, configure redis. in the conf file, set the "daemonize" attribute to "yes", indicating that the Redis service will be started in the form of a later process; and set the "port" attribute to the specified port, the default value is "6379". The "logfile" attribute is set to the specified Log Path, and other attributes can be kept by default.

(5) run the src/redis-server./redis. conf command to start the Redis service. After the startup, you can see the following similar information in the Log Path Just configured:

This handsome icon is the Redis LOGO.

(6) run the client command to verify whether the service is normal:

(7) Redis service Stop command, src/redis-cli shutdown

2.2 conf configuration file description

During deployment, we mentioned the redis. conf file, which is the most important configuration file for Redis. The parameters are described as follows:

Attribute	Description
Daemonize	If the value is "yes", the service is started in the form of a background daemon. If the value is "no", the opposite is true.
Pidfile	Specify the file path for storing the Redis process number
Port	Specifies the port of the current Redis service. The default value is 6379.
Tcp-backlog	This parameter determines the length of the completed Queue (after three handshakes) in the TCP connection, of course, this value must not be greater than the/proc/sys/net/core/somaxconn value defined by the Linux system. The default value is 511, while the default value of Linux is 128. When the system concurrency is large and the client speed is slow, you can set these two parameters.
Timeout	The connection timeout between the client and the Redis server. The default value is 0, indicating that the connection never times out.
Tcp-keepalive	If the value is not 0 and the unit is second, SO_KEEPALIVE is periodically used to check whether the client is still healthy to avoid server congestion. The recommended value is 60 S.
Loglevel	Redis supports four levels: debug, verbose, notice, and warning. Debug: records a lot of information for development and testing; Varbose: useful information, not as many as debug records; Notice: Common verbose, usually used in the production environment; Warning: logs are recorded only for important or serious information; The default value is notice.
Logfile	Log storage path
Databases	Number of available databases. The default value is 16. The default value is 0. The database range is between 0 and (database-1). In my opinion, the concept of DB is similar to that of namespace.
Save	When you save the snapshot information of a database to a disk, there are two corresponding values. For example, if save 300 10 indicates that at least 300 keys are changed within 300 seconds, an event is triggered to save the information to the disk.
Stop-writes-on-bgsave-error	Whether to continue to provide the write service after a persistence error occurs
Rdbcompression	Whether to compress the data to RDB. "yes" indicates compression, and "no" indicates compression.
Rdbchecksum	Whether CRC64 verification is supported during reading and writing. It is enabled by default.
Dbfilename	Image File Name
Dir	The current working directory, configuration files, and image files are all under this directory.
Masterauth	Set the password for accessing the master server
Slave-serve-stale-data	When the slave server and the master server lose connection, or when the data is being copied and transmitted, if this parameter value is set to "yes", the slave server can continue to accept client requests. Otherwise, the following information will be returned to the requesting client: "SYNC with master in SS"
Slave-read-only	Whether to allow slave server nodes to only provide read services
Repl-disable-tcp-nodelay	Specifies whether to disable socket NO_DELAY when synchronizing data to slave. If "yes" is configured, NO_DELAY is disabled. The TCP protocol stack combines packets for unified sending, which can reduce the number of packets between the master and slave nodes and save bandwidth, but it will increase the time for data synchronization to slave. If it is set to "no", it indicates that NO_DELAY is enabled, the TCP protocol stack will not delay the packet sending time, so that the latency of Data Synchronization will be reduced, but greater bandwidth is required. In general, it should be set to no to reduce synchronization latency, but can be set to yes when the network load between the master and slave nodes is already high.
Slave-priority	Specify the slave priority. In a deployment environment where more than one slave exists, when the master node goes down, Redis Sentinel will upgrade the slave with the smallest priority value to the master node. Note that if this configuration item is set to 0, the corresponding slave will never be automatically upgraded to master.
Appendonly	After the append only mode is enabled, redis will append each write operation request received to appendonly. in the aof file, when redis is restarted, the previous state will be restored from the file. However, this will cause the appendonly. aof file to be too large, so redis also supports the BGREWRITEAOF command to reorganize appendonly. aof. It is disabled by default.
Appendfilename	The default value is appendonly. aof.
Appendfsync	Set the aof synchronization frequency. There are three options: always, everysec, and no. The default value is everysec, indicating that the synchronization is performed once per second.
No-appendfsync-on-rewrite	Specifies whether to call fsync during the rewrite of the aof file in the background. The default value is no, indicating that fsync is to be called (whether or not a sub-process is flushing the disk in the background ). Redis will have a large number of disk IO during RDB file writing or afo file rewriting in the background. In some linux systems, calling fsync may be blocked.
Auto-aof-rewrite-percentage	Specify the condition for Redis to override the aof file. The default value is 100, indicating that when the current aof file size exceeds 100% of the size of the last afo file, this will trigger the background rewrite. If it is set to 0, automatic rewrite is disabled.
Auto-aof-rewrite-min-size	Specifies the size of the aof file that triggers rewrite. If the aof file is smaller than this value, automatic rewrite is not triggered even if the Incremental Ratio of the current file reaches the configured value of auto-aof-rewrite-percentage. That is, when both configuration items are met, the rewrite will be triggered.
Lua-time-limit	The maximum execution time of a Lua script, in milliseconds. If it is 0 or negative, it indicates unlimited execution time. The default value is 5000.
Policy-keyspace-events	See reference 3 for button notification events.
Aof-rewrite-incremental-fsync	Whether to adopt the incremental file synchronization policy during aof rewrite. The default value is "yes ". During the rewrite process, a file is synchronized every 32 MB of data, which can reduce the number of disk operations for writing aof large files

 

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