Phoenix is a fault-tolerantreal-time network-attachedstorage device (NASD). Like other NASD architectures, Phoenix provides an object-based interface to data stored on network-attached disks. In addition, it features many functionalities not available in other NASDs. Phoenix supports both best-effort reads/writes and real-time disk read accesses required to support real-time multimedia applications. A standard cyclebased scan-order disk scheduling algorithm is used to provide guaranteed disk I/O performance. Phoenix ensures data availability through a RAID5-like parity mechanism, and supports service availability by maintaining the same level of quality of service (QoS) in event of single disk failures. Given a spare disk, Phoenix automatically reconstructs the failed disk data onto the spare disk while servicing on-going real-time clients without degradation in service quality. Phoenix speeds up this reconstruction process by dynamically maintaining additional redundancy beyond the R...