Many operating systems offer automatic striping of disk sectors across multiple devices. This striping permits disk I/O to continue sequentially without a delay for head positioning. While this technique provides better performance than that achieved on a single disk, it has a disadvantage: combining disks into a single striped unit means that the DBA is no longer able to control the location of individual files on separate devices. If you can only have a few large disk devices on your system, you should consider operating system striping, but multiple devices or multiple RAID-0+1 arrays will usually yield better performance from Oracle.