今天重新安裝VCSA，安裝多次一直卡在80%的畫面不動，顯示正在安裝RPM包，同時log日誌顯示“Failed to authenticate with the guest operating system using the supplied ”，登入控制檯檢視VCSA伺服器進度發現root密碼沒有被設定，手工修改密碼也是失敗。經過網上檢視資料，發現VCSA的安裝盤是有過期日的，因為盤內老的root密碼已經過期，所以root賬戶過期後，安裝程式在執行過程中將無法按照使用者的預設值去修改原系統預設的root密碼。

鑑於此情況，所以嘗試了在80%介面去修改root密碼，VCSA修改root密碼可在系統啟動時完成（可參看如下指引），修改完root密碼並重啟生效後，VCSA的安裝介面便可以開始往後面繼續執行了，直到完成VCSA安裝時的第二部分配置。

如下是VCSA的root密碼修改方法：

To reset the lost forgotten root password in vCenter Server Appliance 6.5:

1. Take a snapshot or backup of the vCenter Server Appliance 6.5 before proceeding. Do not skip this step.
2. Reboot the vCenter Server Appliance 6.5.
3. After the OS starts, press key “e” to enter the GNU GRUB Edit Menu.
4. Locate the line that begins with the word Linux.
5. Append these entries to the end of the line:
   
   rw init=/bin/bash
   
   The line should look like the following screenshot:
   
   
    
6. Press F10 to continue booting.
7. Run the mount -o remount,rw / command.
8. In the Command prompt, enter the command passwd
    and provide a new root password (twice for confirmation):
   
   passwd
    
9. Unmount the filesystem by running this command:
   
   umount /
    
10. Reboot the vCenter Server Appliance 6.5 by running this command:
    
    reboot -f
     
11. Confirm that you can access the vCenter Server Appliance 6.5 using the new root password.
12. Remove the snapshot taken in Step 1 if applicable.