Introduction to Hotpatching

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

This white paper provides a general overview of Hotpatching technology and describes the benefits of using it.

The Microsoft® Windows® operating systems and Microsoft business solutions constitute an environment of choice for many large enterprise customers. For such critical systems, these customers demand high availability and assume the industry standard of "five nines" (99.999%) reliability.

It is important to avoid service interruptions when installing updates on the operating system of such critical systems. Hotpatching provides a mechanism to:

• Update system files without rebooting.

• Update system files without stopping services and processes.

Microsoft reboot reduction initiative

Hotpatching is part of the Microsoft reboot reduction initiative, which seeks to help minimize the need for a full system reboot after installing updates. Reducing reboots is important because IT departments in many organizations implement a time-consuming test cycle every time an update is installed and the system is rebooted. This results in loss of productivity and revenue to the organization until their system is fully verified and operational. Hotpatching allows customers to deploy important updates and patches in a timely, transparent manner without requiring a full system shutdown and restart. This reduces their rollout time.

The following examples demonstrate possible savings from reboot reduction:

• Of the 22 updates that shipped for Windows Server 2003 RTM between April 2005 and August 2005, 15 of them required a reboot. Eight of these could have been hotpatched. This would have reduced the number of reboots by 53%.

• Of the 14 updates that shipped for Windows Server 2003 Service Pack 1 (SP1) prior to August 2005, ten of them required a reboot. Four of these could have been hotpatched. This would have reduced the number of reboots by 40%.