Where Is The Switch Running From; Software Rollback Feature - Alcatel-Lucent OmniSwitch AOS Release 6 Manual

Managing CMM Directory Content

Where is the Switch Running From?

When a switch has booted and is running, the software used will come either from the certified directory
or the working directory. In most instances, the switch boots from the certified directory. (A switch can be
specifically booted from the working directory by using the reload working config command described in
"Rebooting from the Working Directory" on page
Once the switch is booted and functioning, the switch is said to be running from a particular directory,
either the working or certified directory. Where the switch is running from is determined at the time of the
switch's boot-up.
At the time of a normal boot (by turning the switch power on or by using the reload command), a compar-
ison is made between the working directory and the certified directory. If the directories are completely
synchronized (i.e., all files are the same in both directories), the switch will be running from the working
directory. If there is any discrepancy between the two directories (even as small as a different file size or
file date), the switch will be running from the certified directory.
If a switch is running from the certified directory, you will not be able to save any changes made in the
running configuration. If the switch reboots, the changes made to switch parameters will be lost. In order
to save running configuration changes, the switch must be running from the working directory. You can
determine where the switch is running from by using the show running directory command described in
"Show Currently Used Configuration" on page

Software Rollback Feature

The directory structure inherent in the CMM software allows for a switch to return to a previous, more
reliable version of image or configuration files.
Initially, when normally booting the switch, the software is loaded from the certified directory. This is the
repository for the most reliable software. When the switch is booted, the certified directory is loaded into
the running configuration and used to manage switch functionality.
Changes made to the configuration file in the running configuration will alter switch functionality. These
changes are not saved unless explicitly done so by the user using the copy running-config working
command described in
the switch reboots before the configuration file in the running configuration is saved, then the certified
directory is reloaded to the running configuration and changes made to the configuration file in the
running configuration prior to the reboot are lost.
Changes to the configuration file must be initially saved to the working directory by using the copy
running-config working or the write-memory commands. Once the configuration file is saved to the
working directory, the switch can be rebooted from the working directory by using the reload working
command, described in
Likewise, new image files are always placed in the working directory first. The switch can then be reboo-
ted from the working directory. When this is done, the contents of the working directory are loaded and
used to set up the running configuration, which is used to control switch functionality. New image or
configuration files can now be tested for a time to decide whether they are reliable.
Should the configuration or images files prove to be less reliable than their older counterparts in the certi-
fied directory, then the switch can be rebooted from the certified directory, and "rolled back" to an earlier
version.
Once the contents of the working directory are established as good files, then these files can be saved to
the certified directory and used as the most reliable software to which the switch can be rolled back in an
emergency situation.
OmniSwitch AOS Release 6 Switch Management Guide
5-23.
"Copying the Running Configuration to the Working Directory" on page
"Rebooting from the Working Directory" on page
5-18.)
5-18.
July 2010
CMM Files
5-16. If
page 5-5