Microsoft Word Hardware Reconfiguration Methodology V final2

Maintenance types

Although this section places emphasis on the long-term system maintenance of Linux-based computer operating systems, other types of system maintenance are equally suitable depending on the current period from the original deployment of the C2 system. In general, while the various
forms of system maintenance achieve the same overall objective, they are accomplished through different means (i.e. updates, upgrades, code patching, etc.). These various forms of maintenance can be broken down into three general categories: short-term, medium-term, and long-term system maintenance. These three forms of system maintenance can be accomplished using any or all of the various maintenance options provided in [2], although there is likely to be some overlap.

These three maintenance types should help to satisfy the Navy’s key requirement: that a computer operating system is maintainable for the duration of the C2 system’s lifetime. This lifetime is likely to be a period of at least 15 years and possibly as long as 25 years. Currently, it is still uncertain which computer operating system will replace the current C2 operating system aboard the Halifax-class frigates; however, when they are refitted it is very likely that a Linux-based operating system will power the new systems.

1. Short-term

Short-term maintenance is generally the easiest and simplest type to perform on a given Linux operating system. The operating system is generally maintained using updates provided by the distribution’s maintainer. Commercially supported Linux operating systems can easily expect updates to be available for at least the first 2 to 3 years of the system’s life. However, different support contracts with a given vendor may allow for extended periods of operating system updates for possibly as long as 5 years. Updates are normally provided for the duration of the support period of the operating system in so long as the distribution’s maintainer has not switched to a newer version and has ceased support for older operating systems.

Most commercial distributions are able to directly download and install updates, as they become available using sophisticated GUI-based applications. Support contracts may also stipulate that instead updates be to be provided on physical such as quarterly update CD’s.

Updates do not generally cause large operating system disturbances. Instead, they usually provide bug fixes and software patches, but can also provide improved application and system reliability and performance, and less commonly provide improved application functionality. Generally, most updates are transparent to the end users, although from time to time it can occur that certain applications may change slightly from update to another. Normally, however, this should pose no problem to the end users or to system configuration files. In addition, currently supported applications and libraries should not be affected by maintainer-based updates, as they should already have been thoroughly tested by the maintainer. Only rarely do updates upset the balance of system libraries, although when it does happen manual system maintenance may be required to rectify certain inevitable problems. These problems can often be fixed by creating new configuration environments⁴ for the affected applications and libraries.

Updates periodically include newer kernels, although drastic changes in kernels (i.e. switching from kernel 2.4.x to 2.6.x) are indeed a rare occurrence. Minor kernel changes do not normally

⁴ A configuration environment could be one of several things. Normally it is when an application and its libraries are moved to another location on the system and a new system and/or user configuration is created for it and is independent of the rest of the system. Another type is creating a chroot-based environment where the application runs inside of another more restricted environment. Unfortunately, these environments are complex to setup and configure and may not always be an appropriate solution.
result in changes to system calls and which therefore have no tangible impact on the system’s existing applications and libraries. Nevertheless, keeping the operating system’s kernel up to date will improve a system’s ability to undergo a hardware reconfiguration or migration.

Finally, manual system maintenance can be used at any time to manually update and upgrade any application, library, service, or kernel. However, due to the amount of additional work required when performing manual system maintenance related tasks its use is likely to be rather limited, although it is always available if it serves as a more viable solution to an update.

2.