BCCD Bootup Modes

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The default bootup mode for the BCCD is good for many environments and situations, but not all. There are times when a head node may be needed as the DNS/DHCP server, or when a lack of time renders educational configuration steps unnecessary. For this reason, we've developed a few extra bootup modes to make setting up large clusters of BCCD-based systems easier for more situations.

Pressing F3 on the BCCD splashscreen (the first screen you see when the BCCD is first booted from the cdrom) will give you a list of current bootup options. At the time of this writing, the current list of options include:

  • automode
  • nodemode
  • nohotplug
  • quickboot
  • runinram
  • startdhcp

To select one of these specialized modes, first type the framebuffer option, then the name of the mode. For example, if you wanted to use automode with the framebuffer mode 4, then you would type at the boot prompt:

4 automode

There is a brief description of each mode on the F3 options screen. In this page I will go more in-depth to explain more precisely what each mode does.

  • automode - This mode was designed to be used in the situation where we want to set up a large cluster of many nodes for one user. Automode boots up the BCCD in such a way that it doesn't ask for any user input, tries to automatically set up the network with DHCP and DNS on eth0, automatically broadcasts it's public ssh keys (continuously), accepts all other public ssh keys (continuously), and when booted up, does not allow interactive logins of the user 'bccd'. The latter was implemented to discourage others from messing with your nodes. These nodes will work with all parallel applications on the BCCD. In this setup, it's recommended that one head node (the one you sit at) be booted up in the default mode and the rest in automode.
  • nohotplug - Some systems don't like hotplug. Hotplugging is a feature of linux that lets you plug in new devices (such as USB, PCI, and firewire devices) and use them immediately. If for some reason the BCCD doesn't boot up correctly in its default mode, try this mode.
  • quickboot - This mode lets you quickly boot up the BCCD without attempting to configure the network. This means that you must configure the network after boot-up to have any sort of network access. This mode doesn't take advantage of the BCCD as a clustering tool, but more so as a rescue disk.
  • runinram - This mode allows the BCCD to run completely in RAM, which would free up the cdrom. Maybe you've noticed that once the BCCD is booted in default mode, it won't relinquish control of the cdrom until the system is restarted? That is because the operating system is running directly off the cdrom. But by selecting this option, all of the operating system would be running of the system RAM, freeing the cdrom drive. The only drawback is that the system need to have at least 512MB of RAM for it to work.
  • startdhcp/nodemode modes: These two modes exist in the case where no DHCP server exists on the network.
    • The startdhcp mode automatically starts one node as a DHCP server, serving ip's to only BCCD nodes. This node must be booted up first before other BCCD-based nodes may DHCP off it. Some documentation exists on this already at the DhcpSetup page.
    • The nodemode mode automatically boots up the rest of the nodes to only accept DHCP offers from a BCCD DHCP server (booted with the startdhcp mode). This insures that these nodes will accept offers from the correct DHCP server if there is another in the network. If the BCCD is started in nodemode without a BCCD DHCP server on the network, it will fail to obtain an IP.
  • pxeserver and tftpboot: allows the compute note to boot from the BCCD image on the front end node. Use as an alternative booting a compute node with a CD or floppy. At the front end node boot prompt, tftpboot and startdhcp boot prompt options are also required. When prompted to configure the front end node's network, say no to DHCP and instead choose manual configuration. Then set the IP of the pxeserver to 192.168.1.1. Any other IP will result in PXE clients failing to find a DHCP and PXE boot failing. When prompted to configure the compute node's network, saying yes to DHCP works great. Note: requires that the front end node boot with the BCCD-PXE server ISO image


If you would like to see another mode implemented that isn't mentioned here, be sure to add it to the Wish List.

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