Cloud storage is a hot topic at the moment with Google's Google Storage, Microsoft's SkyDrive, iCloud, Dropbox, Mozy and dozens of others. Because of these applications, conserving energy of storage systems is becoming a growing concern in current storage technology. The factors of disk power consumption include disk idle time, poor random writing performance and random read in distributed file systems. Hence, we present an adaptive write cache mechanism - CacheRAID. Redundant Arrays of Inexpensive Disk (RAID) is widely used in modern distributed storage systems. Our CacheRAID aims to improve the random access problems that implicitly exist in RAID techniques to create more idle time of hard drives, and conserve RAID disk array energy. The experimental results show that CacheRAID storage system can conserved 50%∼70% of the power consumption compared to the conventional software RAID system.