I just saw the posted comments for this thread and need to make some major changes for the environment.
First. RHEL 5.9 BMR client/Boot Server support started with NBU 7.6.0.1 (GA) release. It is not supported in NBU 7.5.0.6 release. .That is part of the cause of the SRT creation problem. And yes, the OS compatibility listing is incorrect for this. I will report it to the proper team.
The Tech arrticle noted does indeed reflect the base line cause of the OS load errors, but for Suse 11 SP2. RHEL 5.9 is at a hgher 3.X kernel versioning as well.
The update release version of the OS should be as high or higher than the client image being restored. This is important for RH 5.9 as it introduced a new kernel release.The release major number needs to match. i.e. a RHEL 5.X SRT is needed to restore RHEL 5.X client images. RHEL 6.X SRT will not do and a Prepare To Restore will fail if you try to use the wrong version.
Just to be clear on Red Hat Linux supported levels:
Red Hat Version 4.X is supported up to NBU 7.1.0.X. It is not supported at 7.5 and later.
Red Hat Version 5.0 through 5.7 are supported on NBU 7.0 or later.
Red Hat Version 5.8 support requires NBU 7.5.0.5 or later.
Red Hat Version 5.9 requires NBU 7.6.0.1 or later.
Red Hat Version 6.0 through 6.3 are supported on NBU 7.5.0.5 or later.
Red Hat Version 6.4 requires 7.6 or later.
Red Hat Version 6.5 Requiems 7.6.0.3 or later.
Only 64 bit installs are supported with NBU 7.X.