suvfs: A virtual file system in userspace that supports large files

As a consequence of voluminous growth and proliferation of digital data, the file system size and count limitations have become problematic. The fact is that file systems use fixed length fields within their metadata structures to keep track of volume size, file size and file count, and hence need design (and source) modification to cope up with this growth. In this paper, we propose a Scalable User-space Virtual File System, namely suvfs, which when mounted on top of any file system extends its capability to store and process large files not natively supported by the file system. It works by exploiting the concept of virtual unification to present a large virtual file that spans over a number of legitimate sized physical files. It does so without modifying user applications, system libraries, system calls and even file systems. We implemented it using FUSE framework & evaluated it for performance overhead added by layering it over FAT32 file system. The results indicate that there is a very minimal performance hit encountered by FAT32 with suvfs mounted on top for sequential reading, while as for sequential writing & deletion the performance hit increases with file size but is largely due to FUSE framework & not by suvfs.