warm database, tape device backup

Hi!

I have few question regarding new PostgreSQL database installation.

The potential installation will have to manage over 1.5 TB of data.

Since our customers have an increasing demand for high availability, we
decided to try with PostgreSQL's concept of warm standby database
(http://www.postgresql.org/docs/8.3/static/warm-standby.html)

Apart from having a standby database, we MUST HAVE an enterprise class
reliable backup soltuion and the backup is our major concern now.

My first question is: is there any commercial solution for on-line backup
directly to tape device, eg like HP Data Protector or EMC NetWorker
module for Oracle?

Can we use on-line backup
(http://www.postgresql.org/docs/8.1/static/backup-online.html) using
pg_start_backup and place backup segments onto a tape device directly,
without using the disk storage temporarily (because we have 1,5 TB
database)?

Another question is: Do you have some positive experience regarding warm
standby databases of this size?

Kind regards
Milos Babic