Now i'm reading a file about the raid disk ,
there's a description about hte raind 0 leval that the data will
be write to the disk in the raid by turn.And does the data wrote
to the disk was the same or not the same ?Or any more ,they store
the different part of the data ?Thanks in advance !

Not entirely clear on your question, however as your title is "RAID 0 backup"

There are a number of different RAID configurations that provide redundancy, however RAID 0 (Striping) is not one of them.

If you lose one disk in the RAID 0 set, then you lose the data on the RAID set. RAID 0 is purely used to improve performance, by increasing the number of disk heads performing read and write actions.

If the data is critical, you may want to use RAID 1 (Mirroring) This doesn't give you the improved performance that you get in RAID 0, however it gives you improved stability by reducing the impact of a single disk failure.

You may want to check out the following for further information:

http://en.wikipedia.org/wiki/RAID