REMB: Recoverable External Memory Bitmap of Software RAID

Wang Wei, Yu Li-hua
2016 International Journal of Database Theory and Application  
Distributed block storage system is one of the fundamental components of cloud computing, and many important services, including cloud database, cloud queue, are built upon it. It is common practice to build block storage system based on reliable and efficient Linux open source software, i.e. software RAID, to meet the I/O requirements of cloud database. Bitmap is a critical data structure of software RAID, and hence is important to reliability and performance of this kind of storage system. We
more » ... describe several existing software RAID bitmap management solution, and propose REMB (Recoverable External Memory Bitmap), which is reliable and efficient. Experimental results show that REMB improve cloud database performance by 30%~60%. 338 Copyright ⓒ 2016 SERSC by user have high recovery priority, Ceph's I/O response time will still be severely affected. Open source software, such as iSCSI, MD(Software RAID), DM(DeviceMapper), have implemented core distributed storage functionality, such as remote block device, replication, data slice and combination. They are mature and stable, and run in kernel mode with high I/O efficiency. There are lots of block storage systems [4, [9] [10] [11] [12] based on those open source software. The distributed block storage of NTES(www.163.com) is also implemented based on those open source software, it has been running stably and reliably since putting into use. In this paper, we propose REMB(Recoverable External Memory Bitmap) to improve MD(Software RAID) performance, and implement it in distributed block storage of NTES. Experimental results show that the new schema can improve cloud database's performance by 30%~60%. This paper is structured as follows: Section 2 gives an overview of open source storage software. Section 3 presents three distributed block storage mechanisms based on RAID: internal bitmap, reliable external bitmap, and Recoverable External Memory Bitmap, and discusses their advantages and disadvantages. Section 4 presents experimental setup and numerical analysis results. Section 5 introduces related works. Section 6 summarizes the results and discusses future directions.
doi:10.14257/ijdta.2016.9.10.29 fatcat:xvnkjsbnevd6xcao2ly3vquvj4