• 以树状列出进程及子进程: ps axwef
• 改密码 passwd

• 查看CPU: lscpu nproc

head -n 1 /etc/issue # 查看操作系统版本 - cat /proc/cpuinfo # 查看CPU信息 - hostname # 查看计算机名 ---- env # 查看环境变量

资源

free -m # 查看内存使用量和交换区使用量 grep MemTotal /proc/meminfo # 查看内存总量 grep MemFree /proc/meminfo # 查看空闲内存量 uptime # 查看系统运行时间、用户数、负载 cat /proc/loadavg # 查看系统负载

磁盘和分区 mount | column -t # 查看挂接的分区状态 fdisk -l # 查看所有分区 swapon -s # 查看所有交换分区 hdparm -i /dev/hda # 查看磁盘参数(仅适用于IDE设备) dmesg | grep IDE # 查看启动时IDE设备检测状况

网络

• ifconfig # 查看所有网络接口的属性

进程 ps -ef # 查看所有进程 top # 实时显示进程状态 用户 w # 查看活动用户 id <用户名> # 查看指定用户信息 last # 查看用户登录日志 cut -d: -f1 /etc/passwd # 查看系统所有用户 cut -d: -f1 /etc/group # 查看系统所有组 crontab -l # 查看当前用户的计划任务 服务 chkconfig --list # 列出所有系统服务 chkconfig --list | grep on # 列出所有启动的系统服务 程序 rpm -qa # 查看所有安装的软件包

create 3 new empty files.

Centralized multiprocessors

• uniform memory access (UMA)/symmetric multiprocessors (SMP)
• nonuniform memory access (NUMA):
  • each CPU maintains its own piece of memory
• processor array
• a type of vector computer built with a collection of identical, synchronized processing elements.

Cluster three elements:

• a collection of individual computers,
• a network connecting those computers, and
• software that enables a computer to share work among the other computers via the network.

Cluster structure

• symmetric cluster
• each node can function as an individual computer
• Cluster management and security can be more difficult. Workload distribution can become a problem, making it more difficult to achieve optimal performance.
• asymmetric architecture
• high level of security
• keep all customizations on head node
• performance limitations imposed by the cluster head

I/O represents a particular challenge. It is often desirable to distribute a shared filesystem across a number of machines within the cluster to allow parallel access.

Network design is another key issue. Examples include hyper-tree, hyper-cube, butterfly, and shuffle-exchange networks.

High-availability clusters, also called failover clusters, are often used in mission-critical applications. If you can't afford the lost business that will result from having your web server go down, you may want to implement it using a HA cluster. **load-balancing cluster **is to provide better performance by dividing the work among multiple computers.