WAL backup

Hi all

I'm not sure I understand

http://www.postgresql.org/docs/8.3/interactive/continuous-archiving.html

My problem:

I've huge database ~ 1To (soon 2 To) and I need backup.
I can use pgdump because it's too long to do the backup.
So I like to use «continous-archiving».

For the continuous archiving I do

Modifying postgresql.conf with :

archive_mode = on
archive_command = 'cp -i %p /databases/Archives/%f </dev/null'

restart postgresql

after that I make a big backup:

psql -c "select pg_start_backup('complete_backup');"
rsync -av /databases/pgsql /databases/Archives
psql -c "select pg_stop_backup();"

before this moment I use «continuous-archiving» by put in my crontab
something like (every hours)

rsync -av /databases/pgsql /databases/Archives

is that correct ?

And more important : How long I can keep this the rsync ? I mean after how
long it's good to make a new «big backup» ?

Regards.

--
Albert SHIH
SIO batiment 15
Observatoire de Paris Meudon
5 Place Jules Janssen
92195 Meudon Cedex
Téléphone : 01 45 07 76 26/06 86 69 95 71
Heure local/Local time:
Mar 28 jul 2009 09:23:23 CEST