8.30.2011

Serial over LAN Configuration on UCS Blades

Serial over LAN (SoL) is a mechanism that enables the input and output of the serial port of a managed system to be redirected via an SSH session over IP. SoL provides a means of reaching the host console via CIMC.

The SoL session will display line-oriented information such as boot messages, and character-oriented screen menus such as BIOS setup menus. If the server boots an operating system or application with a bitmap-oriented display, such as Windows, the SoL session will no longer display. If the server boots a command-line-oriented operating system (OS), such as Linux, you may need to perform additional configuration of the OS in order to properly display in an SoL session.
In the SoL session, your keystrokes are transmitted to the console except for the function key F2. To send an F2 to the console, press the Escape key, then press 2.


In order to configure SoL on your UCS blades, you would first need to create a Serial over LAN policy that enables the feature and provides you with the ability to set the baud rate:



Once this is complete, the policy can be applied to your blade's service profile.  Applying this policy to your service profile will not require a blade reboot.



It is also recommended that an IPMI policy be assigned to the service profile as well.  



Additionally, the BIOS of the blade needed to be configured in order to enable the serial interface for console redirection.  This canbe done via a BIOS policy, or directly in the BIOS of the blade by going to Server Management -> Console Redirection.  Ensure that the baud rate matches what was set inside of your SoL policy.






At this point, you can SSH into the IP of the KVM for the UCS blade.  This is found under the Admin tab -> Communication Services -> Management IP Pool.  The username and password that is used to log into the session should be the same as that, which was created previously in the IPMI profile.  You should now be able to log into the console as a user other than root.  Note: If you launch the SSH to CIMC for SoL, you will receive an error message if you are on a Mac:



In Windows XP, I received this same error message, but in order to resolve it, needed to associate my SSH client in UCSM under Options -> External Applications:




After this, I was able to successfully have an SSH session launches to the KVM IP of the specified blade:




Note: I made the following modifications to my RedHat host.  
Added the following to /etc/inittab:
       se:2345:respawn:/sbin/agetty 9600 ttyS0
Added the following to /etc/securetty:
       ttyS0

1 comment:

  1. Trying to follow your steps, I found that after just enabling SoL policy the boot BIOS screen had all the options under Console Redirection greyed out. I had to create a BIOS policy in rtucs/UCS Manager with:
    - Advanced -> Serial Port -> Serial Port A: enabled
    - Server Management -> Console Redirection: serial-port-a (and set baud rate/terminal type appropriately as well)

    but after doing this, I was happily watching boot messages in both the KVM window and my ssh session. (and I did not have to catch that 2 second window to press F2 to get into the BIOS settings, bonus)

    cheers!

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