Answer by Manoj Ranaweera:
You might see some services create a subdomain and others will not. But in most cases, everything runs from a single database which may or may not be distributed.
We run our service from a single database with x hourly backups. Services which are considered mission critical might have much more stringent criteria both in terms of provisioning and backups.
As far as I understand our own infrastructure, we create a number of database entries when a new user sign ups, and start to consume functionality. We also track every action, and provide analytics based on data captured. So the more a user use our product, the costlier s/he becomes in terms of database utilisation and the memory/disk space required to support his/her needs.
We use separate set of servers for processing documents, which are used once when a document is uploaded.