I'm in the early stages of planning our hardware requirements for a migration to Moodle 2.2.x during the coming summer. We're currently running Moodle 1.9.x.
My question is this, can Moodle run in a share-nothing architecture and has anyone got any concrete experience of configuring this?
I think the short answer is no. The longer answer involves questions about why are you looking for this. My collegues point and laugh at me from the time I hotly declared "Nobody outgeeks me", but I had never heard of Shared-Nothing till I read your post. I have been reading every Moodle.org post I could since around 2003, so you might be a pioneer on this one.
From the source of all truth ...
Having looked at it a little more, a true shared nothing architecture through all layers of the stack probably isn't achievable. Moodle doesn't currently support the concept of database sharding etc. It's largely oriented towards a single database. Maybe its possible at the layers above; certainly if you push sessions back to the database then you can scale out your web server cluster.