为什么 RHEL 8 系统被引导到紧急模式，并带有 `Failed to switch root` 错误？

Issue

• 系统被引导到紧急模式，并带有 Failed to switch root 错误？在 rdsosreport.txt 文件中包括了以下错误：

  localhost systemd[1]: Starting Switch Root...
  localhost systemctl[1027]: Failed to switch root: Specified switch root path '/sysroot' does not seem to be an OS tree. os-release file is missing.
  localhost systemd[1]: initrd-switch-root.service: Main process exited, code=exited, status=1/FAILURE
  localhost systemd[1]: initrd-switch-root.service: Failed with result 'exit-code'.
  localhost systemd[1]: Failed to start Switch Root.
  

• 在紧急模式中，/sysroot 中没有 root 文件系统。

  # mount -o remount,rw /sysroot
  # ls 
  /var/lib/nfs/rpc_pipefs