If the Uyuni Server is offline, you can still perform some operations on the terminals. This is useful if the connection between the branch server and the terminals is unstable or has low bandwidth. This feature uses caching to perform updates.
Offline features are available only for Uyuni Server 4.0 and above. You must have the Saltboot and PXE formula packages installed.
If the Uyuni Server is offline, and a terminal is rebooted, it will fall back to a previously installed image.
This will occur in these situations:
If the Saltboot formula has not started within a specified time (default value is 60 seconds).
If the terminal does not acknowledge that the Saltboot formula has started.
If the root partition is specified on the kernel command line (handled by the PXE formula), is mountable (and is not encrypted), and contains
/etc/ImageVersion(which is created by Kiwi).
You can adjust the timeout value by changing the
SALT_TIMEOUT kernel parameter.
The parameter is measured in seconds, and defaults to
SALT_TIMEOUT = 60
For more about kernel parameters, see retail:retail-formula-pxe.adoc.
If there is low bandwidth or an unstable connection between the branch server and the terminal, images can be cached in advance and the upgrade performed on the terminals later on.
To set this up:
Create a service partition on the terminal, which will be used for caching the images.
Download the image to the terminal during regular operations, when a connection is present.
Reboot the terminal, during which the image will be replaced from the cache.