On Fri, Mar 7, 2014 at 12:55 PM, Doug Hellmann <doug.hellm...@dreamhost.com> wrote: > http://git.openstack.org/cgit/stackforge/tooz
This is good stuff. The only solution I could come up with for image cache management was to have yet another service that you would set up to manage the shared image cache resource. The current solution implementation that I've seen relies on the file system resource (under the image caches) to handle the semaphores between the Nova nodes. This is complicated, but not impossible to do correctly. The current design reminds me of a distributed fault tolerant system I worked on in the 1990's ... it was designed in the 1980s and used almost identical locking semantics relying on directory names to determine which process had lock. So this problem set isn't anything terribly new and the proposed solutions aren't anything terribly strange or clever. What I like about the tooz solution is we've found a way to address that same old coordination problem without building yet another service AND without monkeying about with distributed file system locks read by NFS or some other file system sharing mechanism. Instead, we've got this back-channel for coordinating cooperative services. I like this solution a lot because it steps outside the initial problem definition and comes up with something that truly solves the problem, the issue of "who's turn is it?" If someone could point me at some nice primer code for each system I think I might be able to render a more informed opinion. Thanks. -- # Shawn.Hartsock - twitter: @hartsock - plus.google.com/+ShawnHartsock _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
