You say you have raid 0?
"My current configuration is two RAID0 arrays composed of two 500Gb SATA disks each."
this is more jbod

you may need to re-add the failed disk to the array.

I would not use raid 0 as if you lose one drive all of your data will be lost.
your data will be safer with raid 5

see link below

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

RAID 0
RAID 0 (striped disks) distributes data across multiple disks in ways that gives improved speed at any given instant. If one disk fails, however, all of the data on the array will be lost, as there is neither parity nor mirroring. In this regard, RAID 0 is somewhat of a misnomer, in that RAID 0 is non-redundant. A RAID 0 array requires a minimum of two drives. A RAID 0 configuration can be applied to a single drive provided that the RAID controller is hardware and not software (i.e. OS-based arrays) and allows for such configuration. This allows a single drive to be added to a controller already containing another RAID configuration when the user does not wish to add the additional drive to the existing array. In this case, the controller would be set up as RAID only (as opposed to SCSI in non-RAID configuration), which requires that each individual drive be a part of some sort of RAID array.