Project Remus Released

From xen-devel mailing list:

I’m happy to finally release Remus into the wild:

Remus provides transparent, comprehensive high availability to ordinary virtual machines running on the Xen virtual machine monitor. It does this by maintaining a completely up-to-date copy of a running VM on a backup server, which automatically activates if the primary server fails. Key features:

* The backup VM is an exact copy of the primary VM. When failure
happens, it continues running on the backup host as if failure had
never occurred.
* The backup is completely up-to-date. Even active TCP sessions are
maintained without interruption.
* Protection is transparent. Existing guests can be protected
without modifying them in any way.

The NSDI paper at
contains plenty of gore about how it works, and the source has even more.

This is an RFC release, meant to start a discussion on how it might be merged with Xen and Kemari. It is not by any means in shape for application to the Xen tree — right now it is optimized to be easy to port rather than elegant.

This is an old, but fairly stable, release against Xen 3.2, and it lacks HVM support. I hope to release a more up-to-date, HVM-capable version soon, but the port is not yet complete — maintaining synchronized patches between ioemu and the rest of the tool stack has become quite challenging since it switched to an external git repository, and we’re currently a bit short on manpower.