The Research And Implementation Of Fiber Channel RAID And Auto-Delay Strategy

With the development of information technology, storage subsystem is becoming more and more outstanding in the whole computer system, but the problem of storage bottleneck is becoming acute. In order to overcome this status and improve the I/O performance of RAID, the outer channel use Fiber Channel which has the advantage of high performance, long distance connection and high expansibility,the device channel use the high speed SCSI adaptors to improve the disk I/O performance when implement high performance RAID. This method overcome the storage bottleneck effectively.The choice of software platform of RAID has a great impact on the system's performance. In building up software platform, it is important to divide the system into several layers based on the hierarchy principle to make the controller software transplantable. In order to improve the disk I/O performance, we sperate the execute command module and end command module into two layer to finish asynchronously. Thereby, this policy makes full use of the resource of the system, expands the parallel degree. This policy also makes the RAID system can process more than one command at the same time and improve the system performance effectively.In all RAID levels , RAID5 is one of the most common used level. In this level , the slowest stage is small block write. In order to minize the rate of small block write, we use the Auto-delay Strategy, it's a strategy that can improve performance through delay commands. In the delay period, some actions are doing such as merging and sorting to lower the rate of small block write. It's effective to combine commands and return data directly from cache to decreases the number of disk I/O. Proved by experiments, the read performance of throughput has increased 15MB/s, and the write performance of throughput has increased 5MB/s.