一种面向RAID阵列的SSD设计优化方法

随着大数据时代的到来，固态硬盘已经逐渐在大型数据中心得到应用。作为使用最广泛的RAID技术，RAID5也开始应用于固态硬盘阵列，以保证数据的可靠性。然而，RAID5中校验信息需要频繁地更新，尤其在随机访问中，频繁地更新校验信息将会对固态硬盘阵列的性能和寿命造成很大的影响，针对此问题，提出PA SSD(Parity Aware Solid State Disk)控制器设计，从RAID5控制器得到校验信息的逻辑地址，在SSD控制器中设置一个缓存Pcache，暂存更新后的校验信息，并在SSD中将数据和校验分开布局，设置专门的区域存放校验信息。通过实验仿真测试，提出的方法能有效地减少校验信息对SSD的写操作，并且减少了SSD的擦除次数，提升了SSD阵列的性能和寿命。

A RAID oriented optimization for SSD design

With the era of big data, SSDs (Solid State Disks) have been deployed in many large scale datacenters. As the most popular RAID technology, RAID5 has been used in SSD arrays in order to enhance the reliability. However, the parity information of RAID5 is frequently accessed, especially on random accesses dominated workloads. Frequent updating parity information degrades the performance as well as reduces the lifetime of SSD arrays. To solve this problem, the Parity Aware SSD controller design is proposed. The Parity Aware SSD controller gets the logical address of parity from RAID5 controller, and employs a cache, called Pcache, to store the updated parity. Data and parity are stored separately in the SSD. Experiment shows that, our method effectively reduces write operations of parity on SSD and the erase count, thus enhancing the performance and lifetime of SSD arrays significantly.