Source : Microsoft Corporation. SharePoint IT Pro Documentation
Updates can be grouped into three categories based on their purpose and intended audience: hotfixes, cumulative updates, and service packs.
A hotfix is generally created to address a specific problem raised by a customer. There are three different types of hotfixes:
- Critical on-demand A critical on-demand (COD) hotfix is available to address critical problems that cannot be handled via the cumulative update delivery cycle. COD hotfixes are limited to emergency situations, for example, an issue that blocks normal business operations for the customer or an issue for which there is no effective workaround. COD hotfixes are included in the next cumulative update that is released.
- Public update/Microsoft update Occasionally, based on the criticality of an update, a COD hotfix is made available for public download or a Microsoft security update is released as a public update for SharePoint Products and Technologies. The US DST Hotfix – KB941422 is an example of a security update that was released as a public update.
- Post-service pack rollup This update package includes any “SPLock hotfixes,” which are hotfixes that were developed during the SPLock period. The SPLock period is a lockdown on service pack development that is meant to help achieve stability in the development process. Any hotfixes that have been produced before the SPLock period is declared are integrated into the next service pack. SPLock hotfixes are never distributed publically and are only made available during Microsoft Customer Service and Support engagements. SPLock hotfixes require special handling because if the next service pack is applied without the post-service pack rollup, the fix is lost. This could cause data loss, so Microsoft is very careful about releasing these SPLock hotfixes, and provides detailed guidance for each customer scenario
Cumulative updates include all updates that broadly affect support issues that have been released since the last service pack. Since December 2008, cumulative updates have become truly cumulative, and are released on schedule every two months. For more information about cumulative updates, see “Update Releases,” later in this white paper.
Service packs include all of the updates for SharePoint Products and Technologies (that is, all hotfixes and cumulative updates, but not the SPLock hotfixes described above). They also deliver important stability and performance improvements that might not have been requested specifically by customers, but were found internally by the product group. These improvements incorporate further enhancements to user security.