This is analogous to the technique known as striping. It has the same data-integrity characteristics as ordinary independent disk drives. That is, data integrity is entirely dependent on the frequency and validity of backups. This level of function is analogous to the disk striping function described in Logical Volume Striping . Data is striped, as in RAID0, but half of the drives are used to mirror the other drives.
Conscientious backup is still desirable.
If any single drive fails, its contents can be inferred from the parity byte and the surviving data bytes. The parity drive becomes the performance bottleneck in this technique, since it must be written on each time a write occurs to any of the other disks. This spreads the load of writing parity information more evenly. Large RAID configurations tend to be limited by the fact that each RAID is attached to a single SCSI adapter.