PXE boot launches GRUB window if a usb flash drive is installed on the computer.

  • Alright so here is the situation:

    1.) Two different computers (one laptop, one Dell 990) on the same network each boot into a GRUB window if a USB flashdrive is plugged in. (This window just hangs up on “launching cmain()” and never gets anywhere.)

    2.) Each computer has USB booting removed from its boot list.

    3.) When the NIC is taken off the boot list the problem does not happen - the computers will just boot to the harddisk.

    4.) When the NIC is left on the boot list, but the ethernet at the fog server is unplugged the problem does not happen.

    Removing the flashdrive solves the problem of course, but these are user computers and sometimes the flashdrives may be left in. Does anyone know of any settings on the FOG server that could be causing this behavior?

  • My experience is sanboot works on most computers.

    Dell Optiplex 9020s need Grub, even if they are in BIOS mode - not sure why on that but since it works I didn’t really spend time on it.

    HP EliteBooks need Grub, even though they are in BIOS mode.

    I should mention, every computer in my building - and we have maybe 15 different models - is successfully booting to the network every time they are turned on, and getting kicked to Windows when there isn’t a task scheduled. We’ve been working towards that for a long time, and finally got them all over the summer. Imaging is a dream now.

    UEFI computers need various settings - I just go through the list until I find one that works. It’s usually refind.

    Our environment has the correct exit mode per-machine. We have the global default set to sanboot, but we use fog groups when needed to set exit types where needed.

  • Moderator

    @JLE I can say I have almost 100% dells in my environment and I have sanboot as the global exit mode for bios. I do one offs in the host definition.

  • @george1421 Honestly I’m not sure. I did change it to ‘exit’ but then some computers were unable to start. GRUB, for whatever reason, is working with everything on the network. It is an all Dell network, various models from the 755 to 990 - all set up the same way.

    Is there some other setting I would need to make after changing the FOG exit mode to ‘exit’?

  • Moderator

    @JLE Sorry swamped with meeting today. But I have to ask the question, why are you using grub as a global exit mode? Typically you would pick sanboot or exit for bios systems.

  • Alright, figured out my issue. There is a setting under the BIOS that needed to be changed. Setting “Enable Boot Support” to off seems to have fixed the issue. With “Enable Boot Support” in the ON state, even with USB removed from the boot list iPXE was still exiting to the flashdrive. This was super frustrating because some of our document cameras double as a flashdrive. Screenshot attached of the BIOS setting. 0_1471974238334_File_000.jpg

  • The FOG exit mode is set to GRUB. The computers are both set to Legacy Boot in the boot options, with the only thing on the boot sequence being NIC, then Harddisk. They are both set to AHCI. When I click on UEFI in the BIOS settings of either computer - there are no boot order options at all.

    Laptop: Latitude E6520 Windows 7 Pro
    Legacy Boot
    NIC, then HD

    Desktop: OptiPlex 990 Windows 7 Ent
    Legacy Boot
    NIC, then HD

    After iPXE closes both computers launch a GRUB screen(if they have a usb flashdrive in) that I have attached a picture of.0_1471971238641_File_000.jpg

  • Moderator

    For these computers, what is your FOG exit mode?

    FOG does not use GRUB for booting at all. It uses iPXE to manage network booting. But I can understand that once the iPXE menu exits (because the default menu item in the iPXE menu is exit to hard drive), that if your default exit mode is grub first device then it might try to grub boot off the usb drive. Can you confirm this? FWIW: There is a default exit mode for both bios (legacy) and uefi systems. Lets make sure we know which exit mode is doing this.

    Also can you confirm that you have the latest firmware update on those Dell systems?

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