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Thread: Diskless/Stateless HPC node booting

  1. #1
    Join Date
    Feb 2013

    Question Diskless/Stateless HPC node booting

    I'm working on that right now for a 50 node HPC using CentOs (looking at switching to Ubuntu) but I'm having real problems with getting a boot image -- well, booting.

    Does anyone have some experience on a diskless/stateless boot solution with Ubuntu?

    My objective is to install an image to a RAMdrive and run it from there. Since no data needd to be stored or kept, rebooting the system would be the same as a brand new system. Most of the literature I've been working with require an NFS or HTTP server to serve up a root FS. I'm looking to avoid that if possible - I was hoping to serve up the image as one big initramfs.img stuffed into RAM.

    Here's my current detail:
    Main system installed and working well: CentOS (2.6.32-279.19.1.el6.x86_64) but I'd use Ubu 12.10 or 12.04 if there's a recommendation either way)
    PXEboot working well with tftp-server (0.49-7.el6)
    DHCP is serving the PXE boot server information and the client is getting the menus and downloading the vmlinuz and whatever image file named.
    dracut-kernel and -network installed (004-284.el6_3.1)

    Here's my PXE detail:
    kernel Node/vmlinuz
    append initrd=Node/initramfs.img root=/dev/ram0 ramdisk_size=524288 rw ip=dhcp

    The problem I'm hitting is that the root filesystem isn't mounting properly. I get following errors:
    dracut warning: No root device "block:/dev/ram0" found.
    or (depending on PXE variables)
    RAMDISK: Couldn't find valid RAM disk image starting at 0
    No filesystem could mount root

    This has been driving me nuts! Does anyone have any advice? Is PXE/RAMdisk a pretty straight-forward thing with Ubuntu?

  2. #2
    Join Date
    Mar 2013

    Re: Diskless/Stateless HPC node booting

    I can tell you, how to do it for CentOS 5 and 6, but I would like to know how to do it in ubuntu.

    In the Centos/RHEL/Fedora you can use the tool set: livecd-creator program from livecd-tools rpm.
    You would need to create a whatever.ks kickstart file which will specify repos, rpms to install/include, network config, ...

    then you execute:

    LANG=C livecd-creator --config=/pathto/whatever.ks --fslabel=whatever --cache=/pathto/cache --tmpdir=/pathto/tmp

    The result will be /pathto/whatever.iso

    Then you do
    livecd-iso-to-pxeboot /pathto/whatever.iso

    As a result you will get in directory: /pathto/tftpboot/

    the following set of file:


    The main ones you need to PXE boot are vmlinuz (kernel) and root fs (initrd0.img)

    I can give you a sample of the ks file, if you don't know what should be there, but if you google centos livecd-creator, you'll get one.

    Then you configure the PXE server for network boot of the centos (pxelinux, dhcp, tftp, http,...) as usual.

  3. #3
    Join Date
    Mar 2006
    Williams Lake
    Ubuntu Development Release

    Re: Diskless/Stateless HPC node booting

    You want to have a look at LSTP, it should do everything you need.


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