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Solaris Releases, releases everywhere...

As system administrator, you have probably seen many releases of the Solaris software lately. The Solaris release cycle can be confusing and you might not understand the difference between the many Solaris releases that are available to you.

There are actually three types of Solaris releases.

• Marketing releases: Solaris 8
• Update releases: 8 6/00, 8 10/00, 8 1/01, 8 4/01
• Maintenance Update releases: 8 MU1, MU2, MU3, MU4

Marketing releases include major functionality changes. These releases might also contain new interfaces that impact some application compatibility. The Solaris marketing releases end-of-life some features and add new features. In general, Sun works very hard to remain binary compatible between releases, but many vendors recertify their applications. Also, marketing releases might have significant kernel changes that increase the risks associated with compatibility and stability.
Because of the increased risk of compatibility, marketing releases have a major number change such as Solaris 7 to Solaris 8. These releases occur about every 2 years.

Several times a year, Sun offers updates to the Solaris operating system. The updates are designed to provide new functionality in a controlled, compatible fashion. Although new functionality might be present, no interface changes or major changes to any existing feature code is permitted. The result of these controls is complete binary compatibility between update releases of the same marketing release.

These updates are provided in two forms, the Solaris Update release and the Solaris Maintenance Update release. It may be difficult to understand the differences between these two seemingly similiar update releases.

A Solaris Update release is a complete release of the Solaris operating environment. It contains all of the packages included in a marketing release, with bug fixes applied to these existing packages. Plus, there might also be new packages.

The purpose of an update release is to provide:

• New and updated device drivers to support new hardware
• New features in the Solaris operating environment
• Patches integrated into the Solaris system software

Because an Update release contains updated packages, not patches, you can use a Solaris Update release to install the Solaris operating environment on a new system. Or, you can upgrade a system that is already running the Solaris operating environment. When you upgrade to a Solaris Update release:

• The update is delivered as new packages with pre-applied patches. As a result, you can not back out any of the pre-applied patches.
• Any patches previously installed on your system that are not included in the Solaris Update release are removed from your system.

The Solaris Maintenance Update release is a patch release only. This release does not contain any new functionality and bug fixes are delivered by individual patches. The Maintenance Update installation program automatically updates your system without regressing any patches you have previously installed.

When you install the Solaris Maintenance Update, you do not get any support for new hardware nor do you get any new features in the Solaris operating environment. However, you can backout individual patches that you install from the Solaris Maintenance Update.

So, which should you install, the Solaris Update release or the Solaris Maintenance Update release?

You can install or upgrade any system to a Solaris Update release. But, to install a Solaris 8 Maintenance Update release, you must have the Solaris 8 operating environment installed on your system.

To identify the version of the Solaris software that is running on your system type:

# cat /etc/release

The output will look something like this: