Backup Copy of a Production server.

List,

I am in need to copy a production PostgreSQL server data( 1 TB) to an
external storage( Say USB Hard Drive) and need to set up a backup server
with this data dir.

What is the trivial method to achieve this ??

1. Is Sqldump an option at a production server ?? ( Will this affect the
server performance and possible slowdown of the production server ? This
server has a high IOPS). This much size 1.2 TB will the Sqldump support ?
Any bottlenecks ?

2. Is copying the data directory from the production server to an external
storage and replace the data dir at a backup server with same postgres
version and replace it's data directory with this data dir copy is a viable
option ?

# cp -r ./data /media/mydb_backup ( Does this affect the Production
database server performance ??) due to the copy command overhead ?

OR doing a WAL Replication Configuration to a standby is the right method
to achieve this ??

This is to take out the database backup outside the Datacenter and our DC
policy won't allow us to establish a network connection outside the DC to a
remote location for WAL replication .

Any hints most welcome ..

Thank you
Krishane