adding Raid1 to Raid0

All,

I am using RHEL 5.7 and need to setup a Raid0 on3 drives, in the near future I will be adding 3 more drives in an external chassis. I will then be setting these up in a Raid0 and would like to do Raid1 on the two Raid0

Question is when I do the second Raid0 and then the Raid1 will I lose any data?

Will be unable to backup since these are TB drives storing my DB data

Thanks for any assistance,

Jamie