IT organizations understand the importance of applying current security updates, or “patches”, to the operating systems and software applications running in their environment. However, many are reluctant to do so for fear of “breaking” their systems and causing outages.
And, for good reason—these fears are very well-founded. Most IT professionals have had first-hand experience dealing with the aftermath of a failed patch attempt.
A patch is applied only to leave systems in a downed state, requiring an emergency intervention, often in the middle of the night.
How do patches cause outages?
- Flawed patches. Ironically, an update designed to fix a flaw can itself contain flaws. For this reason, many take a “wait and see” attitude and delay applying patches indefinitely.
- Reboot issues. Applying a patch often involves rebooting systems. These can hang or restart out of order.
- Application incompatibilities. Even patches that have been found to be generally stable can be incompatible with specific applications and environments.
- Deployment failures. As with the loading of any software, patch installations can fail during the deployment process.
Bottom Line: Security updates are configuration changes, the most common root cause of system failures. Therefore, a robust patch management process must anticipate and mitigate the causes of failures associated with patching.
Smoke testing is a term used to describe the testing process for servers after patches are applied. 
Estimating an average time for patching servers and PCs can be a bit tricky. It can vary from one month to the next, depending upon the number and complexity of the patches released by your software vendors. You must consider all versions of operating systems and have a complete inventory of all your application software to do this job correctly. Our experience has shown that manual patching of systems takes on average of about 1.5 hours each.
This is a basic cost calculator for you to compute your typical monthly cost for patching your servers, PCs, laptops, tablets and associated application software. It also forms the basis for you to begin calculating your Return on Investment for software patching, or for comparison with alternatives to the manual process of patching operating systems and application software—such as Patch Management as a Service, also known as Vulnerability Management as a Service.