6.3. Synchronizing

An update channel is only as useful as the freshness of the information in that channel. Since the RHN Satellite is designed to be a standalone environment, any update advisories published by RHN must be manually imported and synchronized by the administrator of the RHN Satellite.
During synchronization over the Internet, the RHN Satellite Synchronization Tool performs the following steps:
  1. Connects over SSL to central RHN Servers, authenticates itself as an RHN Satellite, and triggers an export of RHN data — unless a local mount point for RHN-exported data is specified, in which case no connection is necessary. Refer to Section 6.3.2, “Synchronizing Errata and Packages via Local Media” for an explanation.
  2. Examines the export and identifies differences between the RHN Satellite data set and the exported RHN data set. For a particular channel, the following information is analyzed:
    • Channel metadata
    • Metadata of all packages in that channel
    • Metadata for all Errata that affect that channel


    All analysis is performed on the RHN Satellite; the central RHN Servers deliver only an export of its channel information and remain ignorant of any details regarding the RHN Satellite.
  3. After the analysis of the export data, any differences are imported into the RHN Satellite database. Please note that importing new packages may take variable lengths of time. For a large update, an import can take many hours.
The satellite-sync command can be used in two modes: via RHN and via local media.

6.3.1. Synchronizing Errata and Packages Directly via RHN

For customers who want to sync data as frequently as possible and who can initiate connections outside of their own environments, the satellite sync can be run over the Internet through SSL. This is the default setting for the satellite sync script. For example:
satellite-sync -c rhel-i386-as-3
This connects to central Red Hat Network Servers and performs the process described above. Multiple channels can be included by repeating the option. If no channels are specified, all channels on the Satellite will be refreshed.