Docs restructure (#2953)

Needs to be merged into `gh-pages` later on.

docs/installation/manual/2_database.md

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+---
+title: Preparing database storage
+parent: Installation
+nav_order: 2
+parent: Manual
+grand_parent: Installation
+permalink: /installation/manual/database
+---
+
+# Preparing database storage
+
+Dendrite uses SQL databases to store data. Depending on the database engine being used, you
+may need to perform some manual steps outlined below.
+
+## PostgreSQL
+
+Dendrite can automatically populate the database with the relevant tables and indexes, but
+it is not capable of creating the database itself. You will need to create the database
+manually.
+
+The database **must** be created with UTF-8 encoding configured, or you will likely run into problems
+with your Dendrite deployment.
+
+You will need to create a single PostgreSQL database. Deployments
+can use a single global connection pool, which makes updating the configuration file much easier.
+Only one database connection string to manage and likely simpler to back up the database. All
+components will be sharing the same database resources (CPU, RAM, storage).
+
+You will most likely want to:
+
+1. Configure a role (with a username and password) which Dendrite can use to connect to the
+   database;
+2. Create the database itself, ensuring that the Dendrite role has privileges over them.
+   As Dendrite will create and manage the database tables, indexes and sequences by itself, the
+   Dendrite role must have suitable privileges over the database.
+
+### Connection strings
+
+The format of connection strings for PostgreSQL databases is described in the [PostgreSQL libpq manual](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING). Note that Dendrite only
+supports the "Connection URIs" format and **will not** work with the "Keyword/Value Connection
+string" format.
+
+Example supported connection strings take the format:
+
+* `postgresql://user:pass@hostname/database?options=...`
+* `postgres://user:pass@hostname/database?options=...`
+
+If you need to disable SSL/TLS on the database connection, you may need to append `?sslmode=disable` to the end of the connection string.
+
+### Role creation
+
+Create a role which Dendrite can use to connect to the database, choosing a new password when
+prompted. On macOS, you may need to omit the `sudo -u postgres` from the below instructions.
+
+```bash
+sudo -u postgres createuser -P dendrite
+```
+
+### Single database creation
+
+Create the database itself, using the `dendrite` role from above:
+
+```bash
+sudo -u postgres createdb -O dendrite -E UTF-8 dendrite
+```
+
+## SQLite
+
+**WARNING:** The Dendrite SQLite backend is slower, less reliable and not recommended for
+production usage. You should use PostgreSQL instead. We may not be able to provide support if
+you run into issues with your deployment while using the SQLite backend.
+
+SQLite deployments do not require manual database creation. Simply configure the database
+filenames in the Dendrite configuration file and start Dendrite. The databases will be created
+and populated automatically.
+
+Note that Dendrite **cannot share a single SQLite database across multiple components**. Each
+component must be configured with its own SQLite database filename. You will have to remove
+the `global.database` section from your Dendrite config and add it to each individual section
+instead in order to use SQLite.
+
+### Connection strings
+
+Connection strings for SQLite databases take the following forms:
+
+* Current working directory path: `file:dendrite_component.db`
+* Full specified path: `file:///path/to/dendrite_component.db`