I don't recall seeing any documentation on those parts.  I had to poke around 
looking at parts of xCAT to see how it worked.  It's been a few years since I 
did that; so, I don't remember much about the process.  My recommendation 
would be to start looking at things in the rootimg.gz image.  Looking at it 
now, I see that /opt/xcat/xcatdsklspost gets run when rootimg.gz boots.  It 
looks like it downloads all of the postscripts from the management node and 
then run getpostscript.awk which issues a command to xcatd to get the primary 
postscript for that machine.  I've forgotten how xcatd then builds the primary 
postscript.  I do remember that in the module, I had it add the 
partimageng postscript.

So, you'll really have to start digging through how the xcat postscript system 


On Tuesday June 07, 2011, Sunil Venkatesh wrote:
> Josh,
> Is there any place I could find some details on
> "... /Once the compute node is booted with the stateless
> image, it uses NFS to mount some things from the management node, and then
> runs some xcat postscripts,/.... "
> I have the stateless images ready with partimage compiled for PPC. For
> the compute node (power 7) to boot using the stateless images, i need to
> configure the yaboot instead of pxeboot (which is specific to x86). I
> wanted to know where in the startup files the execution of partimage and
> NFS mount is configured. Is it configured by the "genimage" command
> itself? Considering the way in which the nodes are configured in the
> network, it would not be a good idea to let xcat take care of
> configuring the details like DHCPD for netboot. So, I need to make
> changes to the configuration files manually, which is why this query
> came up.
> Thanks in advance.
> Regards,
> Sunil
> On 6/1/11 1:39 PM, Josh Thompson wrote:
> > Sunil,
> > 
> > The "stateless" image I refer to is what is actually booted on the
> > compute node containing the image to be captured.  It's called stateless
> > because it is loaded completely in RAM and does not maintain any state
> > when a reboot occurs.
> > 
> > The partimage binary is part of this stateless image and actually runs on
> > the compute node.  It does not run on the management node.  The
> > management node does not have block level access to the disk on the
> > compute node to be able to capture the image from the disk.
> > 
> > I'll try to describe the process a little better.  The management node
> > issues a reboot command to the compute node.  The compute node uses PXE
> > to load and boot a kernel (vmlinuz), initial RAM disk (initrd.img), and
> > a root filesystem (rootimg.gz) from the management node.  All three of
> > these together make up the stateless image.  Once the compute node is
> > booted with the stateless image, it uses NFS to mount some things from
> > the management node, and then runs some xcat postscripts, one of which
> > is the partimageng postscript.  This postscript determines what
> > partitions are on the compute node and, depending on how the postscript
> > is configured, uses partimage or partimageng to capture an image of the
> > compute node disk that is then saved to the management node. When it is
> > finished capturing the image, it notifies xcat on the management node
> > and then reboots.  xcat reconfigures itself to tell the compute node to
> > boot off of disk at next boot.  When the compute node comes up, it uses
> > PXE to ask the management node how to boot.  The management node tells
> > it to boot off of disk.
> > 
> > I hope that clarifies how the system works.  If any of it is unclear,
> > please ask for further clarification.
> > 
> > Josh
> > 
> > On Wednesday June 01, 2011, Sunil Venkatesh wrote:
> >> Josh,
> >> 
> >> I had one more clarification.
> >> 
> >> partimage binaries run in the management node to capture an (stateless)
> >> image from the compute node right? In that case, is there a need for
> >> these binaries to go into the rootimg.gz??
> >> 
> >> My assumption is, partimage runs on the management node (an intel blade
> >> in our case) to capture a stateless image from a compute node (a power 7
> >> blade) and stores these images under " /install " of the management
> >> node. Please correct me if I am wrong here.
> >> 
> >> Regards,
> >> Sunil
> >> 
> >> On 6/1/11 9:58 AM, Josh Thompson wrote:
> >>> Hash: SHA1
> >>> 
> >>> On Tuesday May 31, 2011, Sunil Venkatesh wrote:
> >>>> Hi,
> >>>> 
> >>>> I used the steps that were mentioned under
> >>>> 
> >>>>
> >>>> ti mag e+and+partimage- ng+to+xCAT+2.x+%28unofficial%29
> >>>> 
> >>>> to enable partimage support for xcat. I wasn't sure if I need to
> >>>> change references to x86&   x86_64 (as directories) to reflect the
> >>>> ppc architecture, as the web page says "The architecture for the node
> >>>> must always be set to x86 for this..". I have with me the vmlinuz
> >>>> (kernel image) and initrd for the capture process. The 2 nodeset
> >>>> commands
> >>> 
> >>> By this, do you mean you have vmlinuz and initrd for your power blades,
> >>> not the ones linked to off of the page you listed above?  If you do,
> >>> that's a good start.  However, you'll also need rootimg.gz.  rootimg.gz
> >>> is the root filesystem for the stateless image.  It also contains the
> >>> partimage and partimageng binaries.  Assuming partimage or partimageng
> >>> can actually capture partitions from power systems, you'll need to
> >>> compile at least one of them to run on power.  For the rootimg.gz image
> >>> I provided, I compiled them statically so that I didn't have to worry
> >>> about including any library dependencies in rootimg.gz.
> >>> 
> >>> It would be a good idea to research how to use xcat's genimage command
> >>> to generate stateless images to learn how to do this.
> >>> 
> >>> If there's any part of the above that you don't fully understand,
> >>> please ask me to clarify it.  Until you have a stateless image that
> >>> you can deploy to your power blades, there's no point in trying to
> >>> debug any VCL specific items.
> >>> 
> >>> Josh
> >>> - --
> >>> - -------------------------------
> >>> Josh Thompson
> >>> VCL Developer
> >>> North Carolina State University
> >>> 
> >>> my GPG/PGP key can be found at
> >>> -----BEGIN PGP SIGNATURE-----
> >>> Version: GnuPG v2.0.17 (GNU/Linux)
> >>> 
> >>> PZYAniP2Eam7nxgiDWUnp5sKPYPO4OMa
> >>> =exBV
> >>> -----END PGP SIGNATURE-----
Josh Thompson
Systems Programmer
Advanced Computing | VCL Developer
North Carolina State University

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