"RAID 6 is interesting to me because it affords you extra protection," said Brad Green, director of information services for the Denton Central Appraisal District for the city and county of Denton, Texas.

Denton Central Appraisal is using economy-class ATA disks for archival and imagery volumes.

"When we have a volume fail it takes forever to rebuild. It doesn't happen that often, but when it does, if you suffer another failure, you lose data," Green said.

While Denton Central Appraisal has yet to experience a volume failure, Green said he just wants to be safe.

Ace Asphalt of Arizona Inc., in Phoenix, has two RAID arrays that they mirrored data between by using an earlier StoneFly product that doesn't have RAID 6 because it wasn't available at the time they purchased it, according to Darin Soll.