12.1 What Is a Patch?

     

Most of us associate a patch with a fix for a defect in the operating system. This is not a patch's only purpose. Patches can also do the following:

  • Enable new hardware and software

  • Deliver new or enhanced functionality, e.g., better performance for an existing operating system release

  • Provide useful utilities

If we think about the software development process, at some point developers and testers will have to ship the product in its current incarnation. No matter how advanced the testing methodologies used, they don't have enough time or resources to put every line of code through every possible scenario. The art of testing is to uncover as many errors as quickly as possible. Ultimately, this can lead to the situation where certain undocumented features arise once the code is running in the myriad of situations it finds itself in out in the big bad world . Anyone who doesn't understand and accept this realistic view of the development process is somewhat misguided (in my view). The dynamic nature of today's operating systems means that HP-UX is composed of a core operating system with periodic updates over time provided by patches. Yes, a portion of these patches will be able to provide defect fixes, but if we are honest and rational about this, we must see that when HP-UX 11i was first developed, we didn't have a Itanium 2 or PA-8800 processor. It is reasonable for HP to publish Hardware Enablement patches for new products that are new technology. In some cases, this will necessitate a complete new operating system (HP-UX 11i version 1.5, 1.6, and version 2 for the Intel Product Family processors), but in many cases HP will produce a patch to support that new product, be it a new interface card or a new software technology. To expect any software or operating system developer to develop, test, market, and release a complete new operating system every time a new XYZ widget becomes available is unreasonable and unrealistic . Although most of you will leave this paragraph with the idea that patches = problems, we can now see that patches do serve other, more beneficial purposes as well.

An HP-UX patch is a partial delivery of software that fixes defects in the original functionality, and in many cases extends it. Almost every patch created is intended for general release to all customers, but the patch may transition into different release states. The current release state, known as the patch status, can be found within the patch README file, which we discuss later.

All patches that should be available to customers use the following patch states. Any value other than those listed here denotes a patch that should be restricted and used only with full understanding and great caution:

  • General Release

    A status of General Release indicates a patch that is approved for widespread use and is the active member of the supersession chain . As the newest available patch, it will contain all known fixes to date for the target software.

  • Special Release

    A Special Release patch is an active patch that was not intended for use by all customers. Patches may be created as Special Releases if a set of customers requires non-standard behavior or configuration-specific changes that would cause problems for others.

  • General/Special Superseded

    When an active patch is replaced by a newer version, it enters the superseded state. Applicable to both General and Special Release patches, patch supersession should not be considered in a negative manner. While the newer patch should contain additional fixes, they may not be critical. The known qualities of an older patch may have greater value than the non-critical improvements.

  • General/Special Recalled

    Under certain conditions, a patch may be recalled and removed from general distribution. As with superseded patches, each system administrator should review the issues documented in the recall notice with the value of the current patch fixes and cost of system change. Patches cannot be partially recalled, and while the generic recommendation will be to remove and replace the patch, the correct action for a specific system may vary.



HP-UX CSE(c) Official Study Guide and Desk Reference
HP-UX CSE(c) Official Study Guide and Desk Reference
ISBN: N/A
EAN: N/A
Year: 2006
Pages: 434

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