The Live Upgrade feature of the Solaris operating environment enables you to maintain multiple operating system images on a single system. An image--called a boot environment, or BE--represents a set of operating system and application software packages. The BEs might contain different operating system and/or application versions.

On a system with the Solaris Live Upgrade software, your currently booted OS environment is referred to as your active, or current BE. You have one active, or current BE; all others are inactive. You can perform any number of modifications to inactive BEs on the same system, then boot from one of those BEs. If there is a failure or some undesired behavior in the newly booted BE, Live Upgrade software makes it easy for you to fall back to the previously running BE.

Live Upgrade software includes a full suite of commands, listed below and described in individual man pages, which implement all of the Live Upgrade features and functions. The software also includes a Forms and Menu Language Interpreter-based user interface named lu(1M). (See fmli(1) for a description of the Forms and Menu Language Interpreter.) The FMLI interface implements a subset of Live Upgrade functions. Unlike the command-line interfaces, output from the FMLI interface is not internationalizable.

The following are some of the tasks you can perform with Live Upgrade software:

• You can make one or more copies of the currently running system.
• You can upgrade to a new OS version on a second boot environment, then boot from that environment. If you choose, you can then fall back to your original boot environment or boot from yet another environment.
• You can install application or OS packages to a boot environment, then boot from that environment.
• You can install OS patches to a boot environment, then boot from that environment.
• From a flash archive, you can install an OS to a boot environment, then boot from that environment. See flar(1M) for information on administering flash archives.
• You can split and rejoin file systems in a new BE. For example, you can separate /usr, /var, and /opt from /, putting them on their own partitions. Conversely, you could join these file systems on a single partition under /.
• You can mount any or all of the filesystems of a BE that is not active, compare the files in any pair of BEs, delete or rename a BE, and perform other administrative tasks.

The Live Upgrade software supports upgrade from any valid Solaris installation medium, including a CD-ROM, an NFS or UFS directory, or a flash archive. (See flash_archive(4) for a description of the flash archive feature.)

In simplest terms, a BE, for Live Upgrade, consists of the disk slice containing a root file system and the file system/device (usually disk) slice entries specified in vfstab(4). This set of slices is not limited to a single disk. This means that you can have multiple BEs on a single device, or have a BE spread across slices on multiple devices.

The minimal requirement for a Live Upgrade BE is the same as for any Solaris boot environment: you must have root (/) and usr filesystems (which might both reside on /). All filesystems except for /, /usr, /var, and /opt can be shared among multiple BEs, if you choose.

Each BE must have a unique copy of the file systems that contain the OS--/, /usr, /var, and /opt. For Live Upgrade purposes, these are referred to as non-shareable (sometimes referred to as critical) file systems. With other file systems, such as /export or /home, you have the option of copying the files to a new BE or, the default, sharing them among BEs. These are referred to as shareable file systems. A BE is made up of a unique copy of one or more non-shareable file systems and zero or more copies of shareable file systems.

Live Upgrade commands support an option (-X) that enables XML output. Characteristics of the XML are specified in a DTD shipped with the product. XML output enables programmatic parsing of portions of the command output.

Live Upgrade supports the notion of a BE description, an optional attribute of a BE. A BE description can be of any length and format. It might be a text string or a binary file. See ludesc(1M) for details.

Below is an example set of steps that you might follow in the use of Live Upgrade software. These steps specify the use of commands rather than lu(1M), the FMLI interface. Many Live Upgrade functions are accessible through lu. Except where lu does not support a function, the choice between lu and Live Upgrade commands is a matter of your requirements and preferences. The following example is by no means exhaustive of the possibilities of the use of the Live Upgrade software.

1. You create a new BE, using lucreate(1M). The first time you run the command, you are required to name the current BE. In lucreate, you provide the name of the new BE and the device (disk) slices you want to use for the BE. You could also specify a source for the new BE other than your current BE. For example, you could specify a Solaris installation CD, or an NFS-accessible directory containing an OS image.
2. Using luupgrade(1M), you upgrade the OS version on your new BE (or on yet another BE you created with lucreate). The luupgrade enables you to upgrade an OS (from any valid Solaris installation medium, including a flash archive), add or remove packages (OS or application), and add or remove patches.
3. You use luactivate(1M) to make the new BE bootable. The next time you reboot your system, you will come up in the new BE.
4. Using lucompare(1M), you compare the system files on two different BEs. This utility gives you a comprehensive list of the files that have differences.
5. Using lumount(1M), you mount the filesystems of a BE that is not active, enabling you to make changes. When you are finished with the changes, use luumount(1M) to unmount the BE's file systems.
6. Upon booting a new BE, you discover a failure or some other undesirable behavior. Using the procedure specified in luactivate, you can fall back to the previous BE.
7. Using ludelete then lucreate, you reassign file systems on the now-deleted BE to different disk slices. You separate /opt and /var from / on the new BE. Also, you specify that swap be spread over slices on multiple disks.

The following is a summary of Live Upgrade commands. All commands require root privileges.

lu

FMLI-based interface for creating and administering BEs.

luactivate

Designate a BE as the BE to boot from upon the next reboot of the system.

lucancel

Cancel a previously scheduled operation.

lucompare

Compare the contents of two BEs.

lucreate

Create a BE.

lucurr

Display the name of the current BE.

ludelete

Delete a BE.

ludesc

Add or change BE descriptions.

lufslist

List the file systems on a specified BE.

lumake

Re-create a BE based on the active BE.

lumount, luumount

Mount, unmount file systems of a specified BE.

lurename

Rename a BE.

lustatus

For all BEs on a system, report on whether a BE is active, active upon the next reboot, in the midst of a copy operation, and whether a copy operation is scheduled for it.

luupgrade

Upgrade an OS and install application software on a BE. Such software includes flash archives, complete OS installations, OS and application packages, and OS patches.

/etc/lutab

list of BEs on the system

lu(1M), luactivate(1M), lucancel(1M), lucompare(1M), lucreate(1M), lucurr(1M), ludelete(1M), ludesc(1M), lufslist(1M), lumake(1M), lumount(1M), lurename(1M), lustatus(1M), luupgrade(1M), lutab(4)

Solaris Live Upgrade software is designed to install and run on multiple versions of the Solaris operating environment. Correct operation of Solaris Live Upgrade requires a certain level of patch cluster for a given OS version. Consult http://www.sunsolve.sun.com for the correct revision level for a patch cluster for your OS version.