Dumping data using pg_dump after chrooting to a different partition

Hi,

I am new to PostgreSQL. We are using PostgreSQL 9.0.2 on our linux
server. We have an instance of PostgreSQL 9.0 running using the primary
partition on the server.

We want to use the pg_dump and psql programs to migrate the data during
our software upgrade process. For upgrade, we plan to do the following:

* chroot to a secondary partition on the server.
* install the software RPMs including PostgreSQL RPMs
* start a secondary instance of PostgreSQL DB server using a different
port and data directory.
* run pg_dump to dump the data from the primary instance to a file.
* run psql to import the data from the file into the secondary instance.

However when I tried to perform the pg_dump as mentioned above, I get
the following error:
pg_dump: [archiver (db)] connection to database "TestDB" failed: could
not connect to server: No such file or directory|<LVL::Debug>
Is the server running locally and accepting|<LVL::Debug>
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?|<LVL::Debug>

pg_dump works before chrooting to the secondary partition. Can you
please provide a way to dump the data after chrooting?

Thanks for your help.

Radha