Two SATA 200GB HDD, can I set one folder to use space on both?
Today I get my new server with 2x200GB SATA HDD and I want use space on both for one folder (that can be /home or some other), can I do that on some way or I must store files in two folders, one on HDD1 and two on HDD2 ??
yeah, raid0 should work, with a few buts; I had some issues with sata and linux software raid though (in 2.6), resulting in slow data corruption, so test everything before you put it in production use (copy around tonnes of files, umount and fsck, see if its clean. This found errors for me almost every time (replacing the disks and controller did not work, but i guess it could be anything. Switching to an ide-controller and ide disks worked out though).
Also, keep in mind that if one of the disk fail your data is lost, so keep a good backup. The probability of failure is larger than normal, since you are depending on 2 separate disks. The reliability is roughly [reliability of single disk] ^ [number of disks], when the reliability is a number between 0 (no reliability) and 1 (infinite reliability)
For your setup i would recommend raid 1, and then more disks if you fill them up. Safer, and good for your nerves..
With 200GB they actually mean 200,000,000,000 bytes. This is different from what we normally mean with 200GB, that is, 200 * 1024^3 bytes. "Loosing" around 16GB is normal. This is just the "fraud" from hdd makes that we see every day. Live with it..