RedHat Advanced Server (RHAS) is a Linux distribution targeted at businesses, in the Internet field or otherwise, who don't want to use either Windows Server, IBM AS400, or a proprietary UNIX such as Sun's Solaris, Hewlett-Packard's HP-UX, Compaq's Tru64, IBM's AIX, or SCO's UnixWare - but neither do those businesses want to rely on a no-cost alternative like FreeBSD, Darwin, or other Linux distributions.
RedHat puts together modifications to the kernel, and to the accompanying programs to take advantage of "larger" hardware - either machines with more than four processors, or more RAM than usual, or some other outsize condition. Without those modifications, the kernel could only use part of the hardware in the machine and the rest would go to waste.
The black bars in the linked graphic represent prohibited transfers - if RedHat sells a copy of RHAS that includes source code that is not properly in their hands, they infringe both reproduction and distribution.
Common Questions:
Why does RHAS cost so much -- I thought Linux was free?
The
$2500 figure is per machine, per year on a subscription basis. The
package includes a support program and provision of bug fixes,
notification of security vulnerabilities, remote monitoring and
administration utilities, as well as
general code updates and new features.