Satellite 5.8 cdn-sync Performance

Introduction

Red Hat Satellite 5.8.0 comes with a new way to synchronize channel-content from Red Hat: cdn-sync. Unlike satellite-sync, which synchronizes content (i.e. channels, packages, errata, and kickstart trees) from RHN Classic servers, cdn-sync retrieves content from Red Hat's CDN servers (the same source which is used by systems registered via subscription-manager). cdn-sync command attempts to keep option parity with satellite-sync where it makes sense to do so.

Although Satellite 5.8.0 itself (when running in connected mode) now registers to Red Hat using subscription-manager, clients registered to Satellite continue to use the RHN Classic tooling (e.g. rhn-register).

While the content-sources differ between satellite-sync and cdn-sync, the goal is to end up with the same results in the Satellite doing the synchronizing. Red Hat is aware of some discrepancies between the two content-sources, and is working on making them consistent. Also, as content is structured differently on CDN, the cdn-sync-mapping package was added, which maps content locations (i.e. repositories with packages or kickstart trees) on CDN to matching channels on Satellites.

Performance Comparison

Tests were run concurrently on the same hardware (4 x Intel(R) Xeon(R) CPU E3-1220 V2 @ 3.10GHz, 8 GB RAM) located in same lab. The operating system was a fully updated Red Hat Enterprise Linux 6 Server.

The tables below show the results from a comparison of sync times for the "Red Hat Enterprise Linux Server (v. 7 for 64-bit x86_64)" repository. The comparison is between the following commands:

5.8.0 Beta (build 20170330) and the 5.8.0 Release Candidate (build 20170515): cdn-sync -c rhel-x86_64-server-7
5.6.0 and 5.7.0: satellite-sync -c rhel-x86_64-server-7

(On the 5.8.0 Beta, sync was without 7.3 kickstart tree, due to a beta bug)

Conclusion

Initial sync of a channel takes far less time on Red Hat Satellite 5.8.0 when compared to 5.7.0 or 5.6.0 (around two hours instead of thirteen, assuming a fast connection to cdn.redhat.com). This is primarily the result of the switch to the CDN-based syncing tool cdn-sync, which retrieves content from the content distribution network, fetching content from a source that should be closer to your Satellite Server.