[root@zabbix-server-it-01 liwm]# systemctl list-unit-files |grep enable
    auditd.service enabled
    autovt@.service enabled
    crond.service enabled
    getty@.service enabled
    irqbalance.service enabled
    kdump.service enabled
    microcode.service enabled
    rsyslog.service enabled
    sshd.service enabled
    sysstat.service enabled
    systemd-readahead-collect.service enabled
    systemd-readahead-drop.service enabled
    systemd-readahead-replay.service enabled
    tuned.service enabled
    lvm2-lvmetad.socket enabled
    lvm2-lvmpolld.socket enabled
    [root@zabbix-server-it-01 liwm]#

    系统开机优化
    [root@db ~]# systemctl list-unit-files |grep enable
    cups.path enabled
    abrt-ccpp.service enabled
    abrt-oops.service enabled
    abrt-vmcore.service enabled
    abrt-xorg.service enabled
    abrtd.service enabled
    accounts-daemon.service enabled
    atd.service enabled
    auditd.service enabled
    autovt@.service enabled
    avahi-daemon.service enabled
    bluetooth.service enabled
    chronyd.service enabled
    crond.service enabled
    cups.service enabled
    dbus-org.bluez.service enabled
    dbus-org.fedoraproject.FirewallD1.service enabled
    dbus-org.freedesktop.Avahi.service enabled
    dbus-org.freedesktop.ModemManager1.service enabled
    dbus-org.freedesktop.NetworkManager.service enabled
    dbus-org.freedesktop.nm-dispatcher.service enabled
    display-manager.service enabled
    dmraid-activation.service enabled
    firewalld.service enabled
    gdm.service enabled
    getty@.service enabled
    initial-setup-reconfiguration.service enabled
    irqbalance.service enabled
    iscsi.service enabled
    kdump.service enabled
    ksm.service enabled
    ksmtuned.service enabled
    libstoragemgmt.service enabled
    libvirtd.service enabled
    lvm2-monitor.service enabled
    mcelog.service enabled
    mdmonitor.service enabled
    microcode.service enabled
    ModemManager.service enabled
    multipathd.service enabled
    NetworkManager-dispatcher.service enabled
    NetworkManager.service enabled
    postfix.service enabled
    qemu-guest-agent.service enabled
    rhsmcertd.service enabled
    rngd.service enabled
    rsyslog.service enabled
    rtkit-daemon.service enabled
    smartd.service enabled
    spice-vdagentd.service enabled
    sshd.service enabled
    sysstat.service enabled
    systemd-readahead-collect.service enabled
    systemd-readahead-drop.service enabled
    systemd-readahead-replay.service enabled
    tuned.service enabled
    vgauthd.service enabled
    vmtoolsd.service enabled
    avahi-daemon.socket enabled
    cups.socket enabled
    dm-event.socket enabled
    iscsid.socket enabled
    iscsiuio.socket enabled
    lvm2-lvmetad.socket enabled
    lvm2-lvmpolld.socket enabled
    rpcbind.socket enabled
    virtlockd.socket enabled
    virtlogd.socket enabled
    default.target enabled
    graphical.target enabled
    nfs-client.target enabled
    remote-fs.target enabled
    runlevel5.target enabled
    [root@db ~]#

    需要关闭的服务：

    全部关闭：

    [root@ecs-3476 ~]# systemctl list-unit-files |grep enabled
    auditd.service enabled
    autovt@.service enabled
    chronyd.service enabled
    crond.service enabled
    dbus-org.freedesktop.NetworkManager.service enabled
    dbus-org.freedesktop.nm-dispatcher.service enabled
    getty@.service enabled
    irqbalance.service enabled
    kdump.service enabled
    microcode.service enabled
    NetworkManager-dispatcher.service enabled
    NetworkManager.service enabled
    rsyslog.service enabled
    sshd.service enabled
    sysstat.service enabled
    systemd-readahead-collect.service enabled
    systemd-readahead-drop.service enabled
    systemd-readahead-replay.service enabled
    tuned.service enabled
    lvm2-lvmetad.socket enabled
    lvm2-lvmpolld.socket enabled
    default.target enabled
    graphical.target enabled
    runlevel5.target enabled
    [root@ecs-3476 ~]# init 3
    [root@ecs-3476 ~]# systemctl set-default multi-user.target
    Removed symlink /etc/systemd/system/default.target.
    Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/multi-user.target.
    [root@ecs-3476 ~]#