The Moodle, and hence Totara cachedir setting is fraught with problems in load-balanced web server environments. The introduction of MUC in 2.4 is a great step forward, but still does not solve the problem of requiring a shared network filesystem for the cache directory on load balanced web servers. Thus far we have been able to architect a shared network filesystem for the cachedir for load-balanced web servers, but it is far from ideal. What can we do to get the remaining cachedir items (ie theme cache, js cache, minify cache) off of shared filesystem and into independent local cache directories (local to each load-balanced web server) or into an appropriate MUC structure? I am hoping Totara might add enhancements to the cachedir problem. In a load balanced environment, the cachedir must be shared and not independent, per Moodle devs and config.php: https://tracker.moodle.org/browse/MDL-38059

UPDATE: As of writing this post I encountered this: http://docs.moodle.org/dev/Server_clustering_improvements_proposal  (check out the localcachedir section)

We are needing improvements in the cachedir problem in order to move forward in high-demand configurations. At the very least getting the cachedir off of network filesystems would be a good step forward.