ScaleIO best practices would be to follow option 2. That is to create individual RAID0 VDs on each disk and let the raid controller back them with the controller cache. This is what we recommend and see in customer environments.  Hope that helps.
Hi all!  Need some advice on building ScaleIO 2.0.x on 5 servers with 4 disks each. These servers will hold some nonprod, but useful activity. So I decided to leave 2 disks on each server for RAID1 (mirror) and create there simple hdd-based VMware datastores. And two other disks from each server assign to ScaleIO. Which path is more efficient: 1. Make RAID0 from 2 disks, apply RAID controller's read/write cache (BBU present) and assign it as 1 RDM disk to ScaleIO 2. Make two separate RAID0 on each server (single disk), apply RAID controller's read/write cache (BBU present) and assign them as 2 RDM disks to ScaleIO 3. Make RAID0 from 2 disks, no cache at all, assign as 1 RDM disk to ScaleIO 4. Make two separate RAID0 on each server (single disk), no cache at all and assign them as 2 RDM disks to ScaleIO  Maybe I've missed something, please advice.
Best setting for RDM on VMware ScaleIO