CentOS开机报错：sd 0:0:0:0: [sda] Assuming drive cache: write through

解决方法：

1. vim /etc/default/grub 文件里去掉 rhgb 参数。
   

   [root@lb-nginx-01 ~/]#vim /etc/default/grub
   GRUB_TIMEOUT=5
   GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
   GRUB_DEFAULT=saved
   GRUB_DISABLE_SUBMENU=true
   GRUB_TERMINAL_OUTPUT="console"
   GRUB_CMDLINE_LINUX="crashkernel=auto biosdevname=0 net.ifnames=0 rhgb quiet"   # 删掉 rhgb，其中"rhgb"表示"redhat graphics boot"，就是图形进度条模式
   GRUB_DISABLE_RECOVERY="true"

2. 然后执行 grub2-mkconfig -o /boot/grub2/grub.cfg
   

   [root@lb-nginx-01 ~/]#grub2-mkconfig -o /boot/grub2/grub.cfg
   Generating grub configuration file ...
   Found linux image: /boot/vmlinuz-3.10.0-862.el7.x86_64
   Found initrd image: /boot/initramfs-3.10.0-862.el7.x86_64.img
   Found linux image: /boot/vmlinuz-0-rescue-4a7be05ea9e048fca01b8d5253845240
   Found initrd image: /boot/initramfs-0-rescue-4a7be05ea9e048fca01b8d5253845240.img
   done

3. 最后  reboot