On small systems it should never be a problem to use one single PostgreSQL server for all the functions listed above. In the standard installation, the ReplicaManager, the pnfs companion are not activated by default. The billing will only write to a file by default.

Whenever the PostgreSQL server is going to be used for another functionality, the impact on performance should be checked carefully. To improve the performance, the functionality should be installed on a separate host. Generally, a PostgreSQL server for a specific funcionality should be on the same host as the dCache cell accessing that PostgreSQL server, and the PostgreSQL server containing the databases for the pnfs server should run on the same host as the pnfs server and the PnfsManager cell of the dCache system accessing it. Accordingly, the pnfs companion and the pnfs server itself will use the same PostgreSQL server.

It is especially useful to use a separate PostgreSQL server for the billing cell.

Create PostgreSQL user with the name you will be using to run pnfs server. Make sure it has CREATEDB privilege.

[user] $ psql -U postgres template1 -c "CREATE USER johndoe with CREATEDB"
[user] $ dropuser pnfsserver
[user] $ createuser --no-adduser --createdb --pwprompt pnfsserver