I am working on potentially porting druid.io to a mesos framework. One limitation for production use is that there is a lot of data cached locally on disk that does not need to be re-fetched during a rolling restart.
If I were to take the simplest mesos route, each instance of the disk-cache-heavy task would have its own executor and would have to refresh the disk cache from deep storage each time it starts. A more complex route would be to have a standalone executor which handles the forking and restarts of tasks in order to maintain the working directory of the task. A slightly more hacky way of doing it would be to allow the disk-cache-heavy task to each have their own executor but use a common SharedFilesystem. But I'm not clear if SharedFilesystem would persist beyond an executor's lifespan. In such a case (where on-disk data would need to be "immediately" available after a rolling restart) is there a recommended approach to making sure the data persists properly? Thanks, Charles Allen
