Error: /var/lib/postgresql/9.3/main is not accessible or does not exist

Question

I have a PostgreSQL db that was running on my server. I tried to do a db_dump and got a weird error message. I eventually thought I would just restart PostgreSQL. However its now stopped and won't restart.

Error: /var/lib/postgresql/9.3/main is not accessible or does not exist

I get the error above when I try and run:

sudo service postgresql start

Can anyone give me some clue please?

I'm running on PostgreSQL 9.3 on Ubuntu 14.04

Answer 1

If you suspect there's something wrong with our database (cluster), make a copy of your database directory before you continue. Just to be sure. On Ubuntu the default directory would be: /var/lib/postgresql/9.3/main/ - but your installation may differ.

Actually, your command should work (in default Ubuntu installations), because the service command starts the postgres server process with appropriate privileges (as system user postgres)

sudo service postgresql start

Translates to something like:

sudo -u postgres /usr/lib/postgresql/9.3/bin/pg_ctl -D /var/lib/postgresql/9.3/main/ -o "-c config_file=/etc/postgresql/9.3/main/postgresql.conf" start

That starts all db clusters you may have. To start a particular one, use the wrapper pg_ctlcluster:

sudo -u postgres pg_ctlcluster 9.3 main start

To get the status of all currently installed db clusters use pg_lsclusters:

sudo -u postgres pg_lsclusters

You must be aware that the data directory is not the same as the config directory in default Debian or Ubuntu Postgres installations. For Postgres 9.3 that would be:

data dir: /var/lib/postgresql/9.3/main/
config dir: /etc/postgresql/9.3/main/

You can check the /etc/postgresql/9.3/main/postgrsql.conf for the actual data dir. It's the line starting with

data_directory = 

The error message indicates that Postgres tries to start with the default data dir, but it is not there or the privileges have been changed. Did you check?

Or are you running a non-default installation?