Weird, people tried not to understand my point, except acejh1987 who advised me to use expert mode for pooling (it's too late now).
Like me, most people here used Cruise Control to setup the pool. I remember I was so scared to see all my drives had gone. I felt some thing wrong here but just couldn't figure out till now (too late).
Once again, like most people here who are newbies I accidently pick "Auto Merge with Balanced Space Priority" to save space. This merge mode balances data among my available drives to ensure that drives are used evenly. My data here is Bluray movies I ripped into many m2ts files in STREAM folders. On a beautiful day, I decide not to use Flexraid or for some reason I cannot restore the pool any more. I'm doomed for sure. Why?
First, I have to say again, I don't know where my movies are. They were definitely splitted into pieces and located everywhere among my hard drives. With thousands of movies, don't tell me to sit back and sort them out throughout HDDs. Don't tell me that is the point of Flexraid pool.
Second, using flexraid pool right now, I can access a folder, which is located on more than 1 disk, Flexraid will access disk one, wait for it to spin up, access disk two, wait for it to spin up and so on. As I am putting more and more disks into the array, I have to wait longer and longer for the disks to spin up. Once again, don't tell that's the point of Flexraid pool.