Node Image Overview
The Y-HPC node images are complete, functional snapshots of the compute node operating systems, typically generated and stored on the head node. When the Y-HPC cluster is being "built", node images are copied from the server to each compute node as it reformats and rebuilds itself, receiving boot directions from the selected template. Through the use of the Y-HPC GUI you may Copy, Rename, Delete, Edit, and Create node images.


Launch the interface
To access the node image management select Edit and then Images from inside the Y-HPC Main Window. Please note the Images drop down list does NOT update without an interface refresh. Close the Image Management window and re-open in order to view recent modifications.


Copy a node image

1. Select an existing node image from the Image pull-down menu.
   
   
2. Select "Copy".
   
   
3. In the new pop-up window, enter the name of the new node image and select "Ok".

The new node image is created and stored in /var/lib/yhpc/images/[image name]/


Rename a node image

1. Select an existing node image from the Image pull-down menu.
   
   
2. Select "Rename".
   
   
3. Enter the new name of the node image and select "Ok".

Delete a node image

1. Select an existing node image from the Image pull-down menu.
   
   
2. Select "Delete".
   
   
3. This will remove the entire node image from the headnode, not just delete the name from the menu. If you desire to simply remove the name but archive the node image, you should copy the node image to a location outside of the /var/lib/yhpc/images/ directory and then delete the original.

Edit a node image
You may add applications, libraries, and data (anything required for your compute nodes to function) to a node image. Images are stored uncompressed in /var/lib/yhpc/images. When imaging the cluster compute nodes, these image directories will be copied (via rsync) to the compute node as is.

1. Select an existing node image from the Image pull-down menu.
   
   
2. Select "Edit".
   
   
3. A terminal will automatically launch and place you into the directory of the selected node image. Now chroot (change root) into an image in order to modify it, granting you a protected root level working environment without potential for accidental modification of the head node OS. This works only if you are running the yhpcgui and chroot command as the root user. If you are running as a non-root user you will be dropped into your /home directory, not the node image directory.
   
   
4. Be certain to make and then use a copy of the base image before modification in order to retain a known, functional state.
   
   
5. When complete with your edit, be certain that /proc, /dev, or any other directory are not left mounted before imaging.

Import/Create a Node Image
A new image may be imported (created) and then added to the GUI. This node image may be pulled-in via an rsync "snapshot" from a functional compute node or built via a chroot DVD, net, or yum install. All mount points inside the chrooted node image directory must be unmounted before adding to the GUI or copied to the compute node. The image is now ready to be imported into Y-HPC.

1. Enter the name of the image you desire to create.
   
   
2. Browse and select the directory of the image you have created.
   
   
3. Select "Import".

The image will be imported into Y-HPC and stored in /var/lib/yhpc/images and made available via the Images pull-down menu.


If required, review Troubleshooting ...