centos7系統初始化

echo "# swappiness=0的時候表示最大限度使用物理內存，而後纔是 swap空間" >> /etc/sysctl.conf
    echo -e "vm.swappiness = 0\n" >> /etc/sysctl.conf
    echo "#  ARP參數，檢查一次相鄰層記錄的有效性的週期。當相鄰層記錄失效" >> /etc/sysctl.conf
    echo -e "net.ipv4.neigh.default.gc_stale_time=120\n" >> /etc/sysctl.conf
    echo "# 路由設定" >> /etc/sysctl.conf
    echo -e "net.ipv4.conf.all.rp_filter=0\n" >> /etc/sysctl.conf
    echo "#啓用源路由覈查功能" >> /etc/sysctl.conf
    echo -e "net.ipv4.conf.default.rp_filter=0\n" >> /etc/sysctl.conf
    echo "#限制arp 協議要發的要求，2 始終使用最好的解決這一目標" >> /etc/sysctl.conf
    echo "net.ipv4.conf.default.arp_announce = 2" >> /etc/sysctl.conf
    echo "net.ipv4.conf.lo.arp_announce=2" >> /etc/sysctl.conf
    echo -e "net.ipv4.conf.all.arp_announce=2\n" >> /etc/sysctl.conf
    echo "#timewait的數量，默認是180000" >> /etc/sysctl.conf
    echo -e "net.ipv4.tcp_max_tw_buckets = 100000\n" >> /etc/sysctl.conf
    echo "#開啓SYN洪水攻擊保護" >> /etc/sysctl.conf
    echo -e "net.ipv4.tcp_syncookies = 1\n" >> /etc/sysctl.conf
    echo "#記錄的那些還沒有收到客戶端確認信息的鏈接請求的最大值。對於有128M內存的系統而言，缺省值是1024，小內存的系統則是128" >> /etc/sysctl.conf
    echo -e "net.ipv4.tcp_max_syn_backlog = 1024\n" >> /etc/sysctl.conf
    echo "#爲了打開對端的鏈接，內核須要發送一個SYN並附帶一個迴應前面一個SYN的ACK。也就是所謂三次握手中的第二次握手。這個設置決定了內核放棄鏈接以前發送SYN+ACK包的數量" >> /etc/sysctl.conf
    echo -e "net.ipv4.tcp_synack_retries = 2\n" >> /etc/sysctl.conf
    echo "#禁用ipv6協議" >> /etc/sysctl.conf
    echo "net.ipv6.conf.all.disable_ipv6 = 1" >> /etc/sysctl.conf
    echo "net.ipv6.conf.default.disable_ipv6 = 1" >> /etc/sysctl.conf
    echo "net.ipv6.conf.lo.disable_ipv6 = 1" >> /etc/sysctl.conf=
    echo "#髒頁的老化時間，默認30秒，多久刷盤一次" >> /etc/sysctl.conf
    echo "vm.dirty_expire_centisecs = 3000" >> /etc/sysctl.conf
    echo "#pdflush多久工做一次" >> /etc/sysctl.conf
    echo "vm.dirty_writeback_centisecs = 500" >> /etc/sysctl.conf
    echo "#若是髒頁到達剩餘的10%，kernel 在調節，而不是pdflush" >> /etc/sysctl.conf
    echo "vm.dirty_background_ratio = 10" >> /etc/sysctl.conf
    echo "#低位內存 30秒一次（到達20%） 小數據文件，隨即數較多，能夠適當把這個值設置大一些，性能更好一些。" >> /etc/sysctl.conf
    echo "vm.dirty_ratio = 30 " >> /etc/sysctl.conf
    echo "#到達字節" >> /etc/sysctl.conf
    echo "vm.dirty_bytes = 0">> /etc/sysctl.conf
    echo "vm.dirty_background_bytes = 0">> /etc/sysctl.conf
    sysctl -p