HPTBBU-04 is a Battery Backup Unit is compatible with RocketRAID 3xxx/4xxx Series Adapters. It maximizes data protection without sacrificing performance. The HPTBBU-04 enhances controller performance and increases SATA and SAS storage system reliability by offering a unique set of data protection and data recovery features, combined with a BBU.The RocketRAID uses both controller cache and disk cache during SATA RAID operations, which strengthens array performance during optimal usage as well as degraded RAID 5 or RAID 6 operations including faster rebuild times.