本系列文章详细记录了在已有两个rac节点的基础上,添加rac第3个节点的过程,期间对rac的使用没有任何影响,rac节点的操作系统均为
1:配置新节点操作系统环境同其他节点一致,包括共享存储,补丁包,内核参数,,用户环境变量等等
[root@rac3 ~]# cat /etc/hosts
127.0.0.1 localhost.localdomain localhost
192.168.1.41 rac1.yang.com rac1
192.168.122.41 rac1-priv.yang.com rac1-priv
192.168.1.141 rac1-vip.yang.com rac1-vip
192.168.1.42 rac2.yang.com rac2
192.168.122.42 rac2-priv.yang.com rac2-priv
192.168.1.142 rac2-vip.yang.com rac2-vip
192.168.1.43 rac3.yang.com rac3
192.168.122.43 rac3-priv.yang.com rac3-priv
192.168.1.143 rac3-vip.yang.com rac3-vip
[root@rac3 ~]# getenforce
Disabled
[root@rac3 ~]# groupadd oinstall
[root@rac3 ~]# groupadd dba
[root@rac3 ~]# useradd -g oinstall -G dba Oracle
[root@rac3 ~]# echo 'oracle' |passwd --stdin oracle
Changing password for user oracle.
passwd: all authentication tokens updated successfully.
[root@rac3 ~]# tail /etc/sysctl.conf
kernel.shmall = 2097152
kernel.shmmax = 2147483648
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
fs.file-max = 65536
net.ipv4.ip_local_port_range = 1024 65000
net.core.rmem_default = 262144
net.core.rmem_max = 262144
net.core.wmem_default = 262144
net.core.wmem_max = 262144
[root@rac3 ~]# sysctl -p
[root@rac3 ~]# tail -4 /etc/security/limits.conf
oracle soft nproc 2047
oracle hard nproc 16384
oracle soft nofile 1024
oracle hard nofile 65536
[root@rac3 ~]# tail -1 /etc/pam.d/login
session required pam_limits.so
[root@rac3 ~]# tail -1 /etc/modprobe.conf
options hangcheck-timer hangcheck_tick=30 hangcheck_margin=180
[root@rac3 ~]# modprobe -v hangcheck-timer
insmod /lib/modules/2.6.9-89.EL/kernel/drivers/char/hangcheck-timer.ko hangcheck_tick=30 hangcheck_margin=180
2:在新节点上配置共享存储,创建相关目录,设置用户环境变量
[root@rac3 ~]# chown -R oracle.oinstall /u01/
[root@rac3 ~]# su - oracle
[oracle@rac3 ~]$ cat .bash_profile
# .bash_profile
# Get the aliases and functions
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/X11R6/bin:/root/bin:/root/bin
export EDITOR=vim
export ORACLE_SID=racdb3
export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=$ORACLE_BASE/product/10.2.0/db_1
export ORA_CRS_HOME=$ORACLE_BASE/product/10.2.0/crs_1
export LD_LIBRARY_PATH=/lib
alias sqlplus='/usr/local/rlwrap/bin/rlwrap sqlplus'
alias rman='/usr/local/rlwrap/bin/rlwrap rman'
export NLS_DATE_FORMAT='YYYY-MM-DD HH24:MI:SS'
export NLS_LANG=american_america.UTF8
export PATH=$ORACLE_HOME/bin:$ORA_CRS_HOME/bin:$PATH
umask 022
[oracle@rac3 ~]$ mkdir -p $ORACLE_BASE/admin
[oracle@rac3 ~]$ mkdir -p $ORACLE_HOME
[oracle@rac3 ~]$ mkdir -p $ORA_CRS_HOME
3:配置各个节点的ssh对等性
[oracle@rac3 ~]$ ssh-keygen -t dsa
[oracle@rac3 ~]$ ssh-keygen -t rsa
使用ssh-copy-id命令将rac3节点的公钥导入到rac1,rac2上的/home/oracle/.ssh/authorized_keys文件中,步骤不在赘述;
最终需要实现在3个节点上使用oracle用户进行相互ssh登陆不需要输入密码

InnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.

Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages have advantages in their respective fields such as data analytics, enterprise applications, and system programming.

MySQL is worth learning because it is a powerful open source database management system suitable for data storage, management and analysis. 1) MySQL is a relational database that uses SQL to operate data and is suitable for structured data management. 2) The SQL language is the key to interacting with MySQL and supports CRUD operations. 3) The working principle of MySQL includes client/server architecture, storage engine and query optimizer. 4) Basic usage includes creating databases and tables, and advanced usage involves joining tables using JOIN. 5) Common errors include syntax errors and permission issues, and debugging skills include checking syntax and using EXPLAIN commands. 6) Performance optimization involves the use of indexes, optimization of SQL statements and regular maintenance of databases.

MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

The basic operations of MySQL include creating databases, tables, and using SQL to perform CRUD operations on data. 1. Create a database: CREATEDATABASEmy_first_db; 2. Create a table: CREATETABLEbooks(idINTAUTO_INCREMENTPRIMARYKEY, titleVARCHAR(100)NOTNULL, authorVARCHAR(100)NOTNULL, published_yearINT); 3. Insert data: INSERTINTObooks(title, author, published_year)VA


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