Synchronizing Files Between Boot Environments

When you are ready to switch and make the new boot environment active, you quickly activate the new boot environment and reboot. Files are synchronized between boot environments the first time that you boot a newly created boot environment. “Synchronize” means that certain critical system files and directories might be copied from the last-active boot environment to the boot environment being booted. Those files and directories that have changed are copied.

Adding Files to the /etc/lu/synclist File

Live Upgrade checks for critical files that have changed. If the content of these files is not the same in both boot environments, they are copied from the active boot environment to the new boot environment. Synchronizing is meant for critical files such as /etc/passwd or /etc/group files that might have changed since the new boot environment was created.

The /etc/lu/synclist file contains a list of directories and files that are synchronized. In some instances, you might want to copy other files from the active boot environment to the new boot environment. You can add directories and files to /etc/lu/synclist if necessary.

Adding files not listed in the /etc/lu/synclist could cause a system to become unbootable. The synchronization process only copies files and creates directories. The process does not remove files and directories.

The following example of the /etc/lu/synclist file shows the standard directories and files that are synchronized for this system.

/var/mail                    OVERWRITE
/var/spool/mqueue            OVERWRITE
/var/spool/cron/crontabs     OVERWRITE
/var/dhcp                    OVERWRITE
/etc/passwd                  OVERWRITE
/etc/shadow                  OVERWRITE
/etc/opasswd                 OVERWRITE
/etc/oshadow                 OVERWRITE
/etc/group                   OVERWRITE
/etc/pwhist                  OVERWRITE
/etc/default/passwd          OVERWRITE
/etc/dfs                     OVERWRITE
/var/log/syslog              APPEND
/var/adm/messages            APPEND

The following example shows directories and files that might be appropriate to add to the synclist file.

/var/yp                    OVERWRITE
/etc/mail                  OVERWRITE
/etc/resolv.conf           OVERWRITE
/etc/domainname            OVERWRITE

The synclist file entries can be files or directories. The second field indicates the method of updating that occurs on the activation of the boot environment. You can choose from three methods to update files:

• OVERWRITE – The contents of the active boot environment's file overwrite the contents of the new boot environment file. OVERWRITE is the default action if no action is specified in the second field. If the entry is a directory, all subdirectories are copied. All files are overwritten. The new boot environment file has the same date, mode, and ownership as the same file on the previous boot environment.

• APPEND – The contents of the active boot environment's file are added to the end of the new boot environment's file. This addition might lead to duplicate entries in the file. Directories cannot be listed as APPEND. The new boot environment file has the same date, mode, and ownership as the same file on the previous boot environment.

• PREPEND – The contents of the active boot environment's file are added to the beginning of the new boot environment's file. This addition might lead to duplicate entries in the file. Directories can not be listed as PREPEND. The new boot environment file has the same date, mode, and ownership as the same file on the previous boot environment.

Forcing a Synchronization Between Boot Environments

The first time you boot from a newly created boot environment, Live Upgrade synchronizes the new boot environment with the boot environment that was last active. After this initial boot and synchronization, Live Upgrade does not perform a synchronization unless requested. To force a synchronization, you use the luactivate command with the -s option.

You might want to force a synchronization if you are maintaining multiple versions of the Oracle Solaris OS. You might want changes in files such as email or passwd/group to be in the boot environment you are activating to. If you force a synchronization, Live Upgrade checks for conflicts between files that are subject to synchronization. When the new boot environment is booted and a conflict is detected, a warning is issued and the files are not synchronized. Activation can be completed successfully, despite such a conflict. A conflict can occur if you make changes to the same file on both the new boot environment and the active boot environment. For example, if you make changes to the /etc/passwd file on the original boot environment and then make other changes to /etc/passwd file on the new boot environment, the synchronization process cannot choose which file to copy for the synchronization.

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Caution - Use this option with great care, because you might not be aware of or in control of changes that might have occurred in the last active boot environment. For example, if you were running Oracle Solaris 10 8/11 software on your current boot environment and booted back to a Solaris 9 release with a forced synchronization, files could be changed on the Solaris 9 release. Because files are dependent on the release of the OS, the boot to the Solaris 9 release could fail because the Oracle Solaris 10 8/11 files might not be compatible with the Solaris 9 files.

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