Microsoft Word Hardware Reconfiguration Methodology V final2

Medium-term

As operating system update support is dropped in favour of supporting more recent versions of the operating system, an upgrade will eventually be required to move up to the next level of technology unless for some reason manual system maintenance is preferred. Upgrades, however, are usually preferable to manually maintaining and supporting an operating system due to the complexity involved. Thus, an upgrade is an operating system medium-term maintenance solution. It can be expected that a deployed operating system will likely have to undergo an upgrade from one operating system version to a newer one around every 5 years, unless extended operating system update support is stipulated in the support contract with the vendor.

However, simply because update support has stopped may not be incentive enough to justify upgrading, especially if large changes are entailed. Conversely, upgrading may be justifiable due to new technical innovations by providing features such as a substantially newer kernel, applications, services, and libraries. An older operating system can normally be upgraded with only a few problems to be expected along the way. It is, however, probable that at least several important applications may no longer work as expected due to application and/or library-based changes. If this occurs, part of the upgrade can normally be rolled back and the missing files recovered from backup. Then a new configuration environment can be created for the affected applications and libraries. This may not always fix the problem, however, and sometimes the only way to fix it is to track down the root cause(s) of the problem using the tools detailed in Section 2.4.5.3. In the worst of cases, applications and/or libraries that do not work properly can be recompiled and/or modified from source code; however, this can be time consuming and complex to the uninitiated.

Therefore, unless there are valid reasons for not upgrading to a newer operating system version when update support has been terminated, in-house laboratory testing should be conducted to confirm that upgrading would result in a stable operating system. In addition, in-house testing will confirm if the changes caused by an upgrade conform to organizational requirements and policy (i.e. changes in operating system security policies).

Once the system and its applications have been deemed functional, the system can then be updated using vendor provided updates. Once an upgrade is successful, subsequent updates can then be applied to the system until the next major upgrade is available or necessary. It is likely that updates for commercially supported operating systems will be available for as long as another 5 years before the next major upgrade is required.

Therefore, upgrading is a medium to long-term system maintenance solution. Its caveat is that upgrades eventually must themselves be superseded by a series of updates only to be followed by

another upgrade. With time, through the successive implementation of updates and upgrades the operating system may begin to show symptoms of software decay. Software decay occurs when enough small changes have been made to a computer system where it no longer behaves as expected due to the number of progressive modifications that have substantially altered the system, its usability and reliability. This is generally caused by an excess of library incompatibilities and inconsistencies that can no longer be easily managed through alternate configuration environments. Although rare this can sometimes be caused by system call changes in the kernel. This type of issue is almost never seen for updates designed for the original operating system but can and may occur as time progresses and subsequent upgrades and updates have been applied to the system. This may take as long as 15 or more years before coming into full effect.

3.