Distant mirroring

Hello,

I'm trying to install a solution to permit me to :
- Secure the datas, without RAID
- Giving ability to increase the potentiality of the database towards
the needs.

I have read about slony, DRBD, pgpool....

I don't find the good system to do what I want.

I manage for now 50 millions of request per month.

I will reach 100 millions in the end of the year I suppose.

There is 2 difficulties :
1 - is the storage : to get faster access,it is recommend to use SAS 15
000 tps. But the disk I can get are 149 GO of space. As the database is
growing par 1,7 Go per week at the moment, it will reach is maximum in 3
month. I can add 3 disk at least so It can go to 9 month. What to do
after, and especially what to do today to prevent it?
2 - The machine will treat more and more simultaneous entrance, so I
need to loadbalance those inserts/updates on several machine and to
replicate the datas between them. It's not a real problem if the data
are asynchrony.

I'm migrating to postgresql 8.3.3.

Thanks for all your remarks, suggestions and helps

David