I need to revisit this as its still not overly clear. In M2.6 the recommendations are to use a MemcacheD server to store user sessions.
We are using a shared disk on a SAN using OCFS2 as a clustering file system. Here comes the confusion as its not clear whether we would have to set up a separate MemcacheD server and share this ,also using OCFS2 for user sessions, MUC etc or have a local instance of MemcacheD on each web node to store user sessions. In which case I would imagine that unless we have session affinity on the load balancers (which we would do), the user will lose session data as they are moved around the separate web nodes.
Make sense, probably not!
So hows it done then? I think the recommendations here appear to be based on hardware rather VMs, which to me is a little narrow. We all know that hardware with directly attached disks out performs VM and San based disks but it is the future and we cannot avoid it. The last three companies I have worked for have gone entirely virtual. But thats another argument
1. Put memcacheD on both web nodes and employ session affinity on LB's for user sessions?
2. Or create a central MemcacheD server and store user sessions on that? OCFS2 anyone?
3. Forget MemcacheD for user sessions and use the database to store them (also set as default by Moodle since 2.5)
4. Kill ones self?
5. Start a Moodle committee to get this nonsense cleared up forever?
6. Go away