This feature is new in the Solaris 9 8/03 release.
Solaris Live Upgrade provides a method of upgrading a system while the system continues to operate. While your current boot environment is running, you can duplicate the boot environment, then upgrade the duplicate. Or, rather than upgrading, you can install a Solaris Flash archive on a boot environment. The original system configuration remains fully functional and unaffected by the upgrade or installation of an archive. When you are ready, you can activate the new boot environment by rebooting the system. If a failure occurs, you have a safety net. You can quickly revert to the original boot environment with a simple reboot. Thus, you eliminate the normal downtime of the test and evaluation process.
New features in Solaris Live Upgrade 2.1 provide the following new functionality.
Solaris Live Upgrade uses Solaris Volume Manager technology to create a duplicate boot environment that contains file systems with RAID-1 volumes (mirrors). The mirror provides data redundancy for any file systems, including the root (/) file system. With the lucreate command, you can create mirrored file systems that contain up to three submirrors.
With the lucreate command, you can now exclude some files and directories that would normally be copied from the original boot environment. If you have excluded a directory, you can also include specified files and subdirectories under that directory.
For further information, see the Solaris 9 9/04 Installation Guide.