1.问题描述
Ubuntu 16.04 Server LTS升级内核时，每次都跑出来“W: mdadm: /etc/mdadm/mdadm.conf defines no arrays”的提示。明明没有用RAID,查了mdadm.conf也有没有任何相关的配置。虽然不影响使用，但是强迫症患者还是觉得很不爽。

2.解决办法
先删除mdadm.conf文件

lwk@ubuntu:~$ sudo rm /etc/mdadm/mdadm.conf

再用update-initramfs命令，自动生成新的mdadm.conf文件。

lwk@ubuntu:~$ sudo update-initramfs -u perl: warning: Setting locale Failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset),LC_ALL = (unset),LC_MONETARY = "zh_CN.UTF-8",LC_ADDRESS = "zh_CN.UTF-8",LC_TELEPHONE = "zh_CN.UTF-8",LC_NAME = "zh_CN.UTF-8",LC_MEASUREMENT = "zh_CN.UTF-8",LC_IDENTIFICATION = "zh_CN.UTF-8",LC_NUMERIC = "zh_CN.UTF-8",LC_PAPER = "zh_CN.UTF-8",LANG = "en_US.UTF-8" are supported and installed on your system. perl: warning: Falling back to a fallback locale ("en_US.UTF-8"). update-initramfs: Generating /boot/initrd.img-4.4.0-119-generic lwk@ubuntu:~$ 

天下太平。

https://www.tongfu.info/solve-ubuntu-w-mdadm-etcmdadmmdadm-conf-defines-no-arrays/