3. Tested, Stable Products, Rapid Bugs Fixes and Predictable Lifecycles
Companies like Red Hat carry out testing, tuning and troubleshooting across a wide range of hardware, configurations and applications before it allows any new code from open source projects to trickle down into their subscription products, Haff explains.
This requires considerable corporate resource--people, processes, systems and infrastructure--and arguably it's the stability and reliability that results from this, more than anything else, that you are paying for with your subscription.
The effect of this slow trickle down of technology is that the current version of RHEL is usually several releases behind Fedora, and since the Fedora development community doesn't provide fixes to outdated packages, Red Hat provides interim security or bug fixes to RHEL packages as part of the subscription. New features that appear in the latest releases of Fedora may also be back ported to the RHEL, Haff says.
Subscription products also tend to have a defined lifecycle that specifies the length of time they will receive enhancements, bug fixes and security updates, unlike open source projects. This allows you to plan your upgrades and bring hardware refreshes into line with upgrades where necessary.
4. Extra Functionality
In many cases it makes sense to pay for a product that has additional features that the underlying open source offering lacks. For example, Big Switch Networks is the sponsor of an open source network controller project called Floodlight, and its Big Network Controller (BNC) product is built around it. The benefit of paying for BNC is the extra functionality BNC provides to enhance the Floodlight controller.
"BNC uses Floodlight at its core, but it also includes additional modules for tracing, statistics, performance scalability and so on. These extra modules are not open source," says Andrew Harding, a senior director at Big Switch Networks. BNC also offers a multiple node deployment capability--a feature which most enterprises look for in a network controller to allow for failover, but which is absent in the Floodlight network controller.
5. Integrated Hardware and Software Solution
It's often worth paying for a hardware and software package that includes open source software to ensure you get a solution that is guaranteed to work. For example, Digium is the creator, maintainer and sponsor of Asterisk, an open source PBX telephony software project.
In additoin to offering SLA-backed support for Asterisk, the company sells hardware designed to enhance the software in the same way that Big Switch Networks offers additional paid-for software modules to enhance Floodlight.
The hardware includes redundancy appliances designed to enable physical-layer failover of telephone connections, so that in the event of a hardware or software failure on a server running Asterisk, communications are automatically switched to a backup Asterisk server.
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