In this context, the term "diskless" refers to any OS image that can be created and prepared locally on the HP Insight CMU management server and then served over the network to a PXE-booted set of compute nodes. A few different implementations of "diskless" OS images are:

•stateful NFS-root — All reads and writes from the target compute nodes occur on the central NFS server.

•stateless NFS-root — Reads occur from the central NFS server, but writes occur in memory (in a tmpfs filesystem).

•stateless ramdisk — The entire OS image is transferred during the PXE-boot process, and unpacked in memory.

The initial diskless support in HP Insight CMU was based on the system-config-netbootpackage in Red Hat Enterprise Linux (RHEL) versions 4 and 5. This is a "stateful NFS-root" implementation. The system-config-netbootpackage was deprecated in RHEL6, but HP Insight CMU continues to support it.

The diskless integration programs are installed in the /opt/cmu/diskless/ directory. For example, the programs to support the system-config-netbootdiskless implementation reside in /opt/cmu/diskless/system-config-netboot/. These programs are called by HP Insight CMU at predefined times, which are documented below.

The diskless API requires that the following programs exist.

NOTE:

The term <DISKLESS> here refers to the name of the implementation "toolkit".

/opt/cmu/diskless/<DISKLESS>/cmu_<DISKLESS>_build_image /opt/cmu/diskless/<DISKLESS>/cmu_<DISKLESS>_delete_image /opt/cmu/diskless/<DISKLESS>/cmu_<DISKLESS>_register_node /opt/cmu/diskless/<DISKLESS>/cmu_<DISKLESS>_unregister_node /opt/cmu/diskless/<DISKLESS>/cmu_<DISKLESS>_boot_node /opt/cmu/diskless/<DISKLESS>/cmu_<DISKLESS>_diskless_check

7.2.1 Build diskless image

The build_image program is called when an HP Insight CMU diskless logical group of type <DISKLESS> is created. This program is called with the following arguments:

-l<CMU diskless logical group name>The name of the new logical group.-g<"golden node">

The hostname/IP of the compute node from which to extract the diskless OS filesystem.

-k<"kernel version">

The version string of the kernel that resides on the "golden node" and is to be the diskless kernel.

The build_image program is expected to install and prepare the diskless OS filesystem in /opt/ cmu/image/<CMU diskless logical group name>/. This program may also prepare the kernel and any initrd required in order to PXE-boot this diskless image.

If this program returns successfully (zero exit code), then the new HP Insight CMU diskless logical group is created in the HP Insight CMU database. If this program returns with a non-zero exit code, then the new HP Insight CMU diskless logical group is not created.

7.2.2 Delete diskless image

The delete_image program is called when an HP Insight CMU diskless logical group of type <DISKLESS> is deleted. This program is called with the following argument:

7.2 HP Insight CMU diskless API 115