一、现像：
二、处理过程
第一时间找网工，更换光纤线和模块，交换机换为核心交换机，仍然这样，我一共购买了某擎四台服务器，前后所有的都是这样。
网工怀疑这批光纤线有问题，只能让我们等、等。。。。。采购
（1）查看当前网卡 RX/TX 参数：
[root@hadoop02 ~]# ethtool ens26f0
Settings for ens26f0:
Supported ports: [ FIBRE ]
Supported link modes: 10000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: No
Supported FEC modes: Not reported
Advertised link modes: 10000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 10000Mb/s
Duplex: Full
Port: FIBRE
PHYAD: 0
Transceiver: external
Auto-negotiation: off
Supports Wake-on: d
Wake-on: d
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes
[root@hadoop02 ~]# ethtool -g ens26f0
Ring parameters for ens26f0:
Pre-set maximums:
RX: 4096
RX Mini: 0
RX Jumbo: 0
TX: 4096
Current hardware settings:
RX: 512
RX Mini: 0
RX Jumbo: 0
TX: 512
(2)
参照
https://docs.azure.cn/zh-cn/articles/azure-operations-guide/virtual-machines/linux/aog-virtual-machines-linux-howto-optimize-performance-of-linux-nic-by-ethtool
Pre-set maximums 中的 RX/TX 值为该网卡的 Buffer size 最大值；
Current hardware settings 中 RX/TX 值代表该网卡当前的 Buffer size 大小。
所以，设置的 Current hardware settings 的 RX/TX 值必须在 Pre-set maximums 的限制之内。
[root@hadoop02 ~]# ethtool -G ens26f0 rx 18000 tx 2500
[root@hadoop02 ~]# ethtool -g ens26f0
Ring parameters for ens26f0:
Pre-set maximums:
RX: 4096
RX Mini: 0
RX Jumbo: 0
TX: 4096
Current hardware settings:
RX: 4096
RX Mini: 0
RX Jumbo: 0
TX: 2504
[root@hadoop02 ~]# chmod -x /etc/rc.d/rc.local
[root@hadoop02 ~]# vi /etc/rc.d/rc.local
[root@hadoop02 ~]# cat /etc/rc.d/rc.local
#!/bin/bash
# THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES
#
# It is highly advisable to create own systemd services or udev rules
# to run scripts during boot instead of using this file.
#
# In contrast to previous versions due to parallel execution during boot
# this script will NOT be run after all other services.
#
# Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure
# that this script will be executed during boot.
touch /var/lock/subsys/local
ethtool -G ens26f0 rx 18000 tx 2500
(3)验证
[root@hadoop02 ~]# ethtool -g ens26f0
Ring parameters for ens26f0:
Pre-set maximums:
RX: 4096
RX Mini: 0
RX Jumbo: 0
TX: 4096
Current hardware settings:
RX: 4096
RX Mini: 0
RX Jumbo: 0
TX: 2504
再次安装CDH后正常