CentOS view CPU, disk, memory usage, and how to clean up memory

The system in the long run, the available memory will gradually become less, if there is no mechanism to do monitoring and regularly clean up the characters, the server will have a lot of hidden dangers, the following operations to manually check and clean up: Check the basic situation of the server to see memory usage

    Free-m

View CPU Usage

    Top #查看进程运行情况

View disk and partition conditions

View network conditions

    Ifconfig

View Port Usage

    #1. Method One
    lsof-i: port number

    #2. Method two
    netstat-apn|grep port number

Server Troubleshooting and optimization Cleaning up Memory

    #1. "Recommended" release of the Web cache (to-free pagecache),
    sync
    echo 1 >/proc/sys/vm/drop_caches

    #2. Release directory entries and indexes (to free Dentries and Inodes)
    sync
    echo 2 >/proc/sys/vm/drop_caches
    #3. Free Web page caching, directory entries, and indexes (to $ pagecache, Dentries and Inodes):
    sync
    echo 3 >/proc/sys/vm/drop_caches

Select the appropriate way to clean up, and then perform a view of memory, you can see that memory has a lot of free space;