Backup Policy & Disk Space Issues

Hi,

In the company, we're facing with serious disk space problems which is
not caused by PostgreSQL, but the nature of our data. Database sizes are
around 200-300GB, which is relatively not that much, but databases
require strict backup policies:

- Incremental backup for each day. (250GB)
- Full backup for each week of the last month. (4 x 250GB)
- Full backup for each month of the last year. (12 x 250GB)

As a result, we require a space of size (roughly)

250 + 4x250 + 12x250 = 17x250 = 4250GB = 4.15TB

for each server per year. Considering we have ~15 servers,

15x4250 = 63750 = 62.25TB

as can be seen, growth of the backed up data sizes have almost no
relations with the actual data sizes. At the moment, we're using tape
drive cartridges for weekly and monthly backups. But the incremental
backups, plus the database itself requires a constant space of size
~500GB.

To summarize, as a DBA most of my time is wasting with validating if the
backup policies performed right, cartridges captioned correctly, etc.
What are your experiences with similar sizes of data? How do you cope
with backups? Do you recommend any other hardware/software solutions?

Regards.