Research On Scalability Optimization Of Pram FS

Storage Class Memory has characteristics of low latency memory and high random operatations, and it is nonvolatile after power like SSD and disk, which is considered to be an important trend of computer storage, so the research and industrial organization are paying more and more attention to SCM.Protected and Persistent RAM File System(PramFS) is a kind of open source file system on linux, which was first used in embedded equipment, so it can not be applied directly on the desktop or server system. This paper will reaserch on PramFS file directory structure and index structure to design Scalable Persistent RAM File System, which has good scalability for storage class memory.Firstly for PramFS using multistage two-way linked list to organize file directory,which is not available for the exsiting file system, SPFS uses AVL tree structure. In AVL tree we use hash value as key value. In directory different key value nodes are organized as AVL tree, the same value nodes are arranged in a linked list structure. SPFS also uses a set of hash table to help index node query, if the node does not exist in the hash table lookup entered into the AVL tree directory structure. The Optimization of directory structure increases the search speed and improves mapping efficiency. Secondly file index structure refers to the file organization on storage devices. SPFS uses metadata information to store file index structure height, which can transform the index structure to store different height to the size of the file to. Experimental results show that the system directory structure and file index structure after optimization has good scalability in the directory size and file size, and the performance has been obviously improved.