Abstract: Based on a thorough analysis on the fault tolerance capability on various existing storage systems, we proposed a new hierarchical, highly reliable, multi-disk fault tolerant storage system architecture; High Availability Object Story ge System (HAOSS). The HAOSS is composed of two layers; the upper-layer and the lower-layer. I}he upper-layer achieves the high availability by storing multiple replicas for each storage object in a set of storage devices. The indi-victual replicas can service the I/O requests in parallel so as to obtain high performance. But the effective disk space uti-lization rate for the upper-layer is relatively low. The lower-layer deploys RAIDS，RAID6 or RAID-Blaum coding schemes to tolerate multi-disk failures. The disk utilization rate of coding schemes is higher than that of multiple replicas. These advantages come at the price of more complicated fault tolerant coding schemes, which involve a large amount of calculation for encoding and cause an adverse impact on the I/O performance. The HAOSS puts new objects and hot objects in its upper-layer,so that the majority of the rectuests are absorbed by the upper-layer,hence achieving guaranteed system I/O performance. The main purpose of the lower-layer is to provide a reservoir for the cold data. In a 1000Mb Ethernet interconnection environment, with a request block size of 1024kB, the sequential read performance for a HAOSS server reaches 104MB/s, which is very close to the theoretical maximum effective bandwidth of Ethernet networks.

Key words: Data organization,High availability,Objcct storage systcm,Fault-tolerant