Thanks for your answer.

Our system & network admin didn't recommand us to use RAID Software because he says it often fails, is it right with Open-E ?

We plan to buy this server with 8 HD (750GB SATA2) : http://www.actualis.com/app/acheter/...HSAPXFB16.html

With this server, is it possible to do 2 RAID 6 Arrays of 4 disks each (so 1.5 TB/Array) with the hard raid controler, and then, a RAID 0 Hardware of the 2 RAID 6 arrays to make a single logical volume of 3 TB ?

After, when we'll need more space, we'll add 8 more HD in the server, make the same RAID 60 array as the one already in the server and then, merge the two RAID 60 Array into a single logical volume one of 6 TB ?
How mane downtime that evolutive operation will cost ? Is it possible ?

Thanks in advance. I've just ask for the demo-cd.
Aurélien GOUTAL