A Stackable Filesystem for Realtime Network Backup

Abstract

We propose and implement a new stackable filesystem to backup data on a network in realtime, and discuss the basic performance. Conventional mirroring technologies utilize the mirroring function on the device layer or need a special filesystem, the allocation of the disk and the specific format of the filesystem are needed, and so the filesystem allocation is fixed. Therefore, when a backup operation is required for new services, mirroring in the device layer or the special filesystem cannot be implemented. The proposed stackable filesystem realize the backup functions without changing the device and filesystem allocations by the VFS mechanism. So it enables the realtime network backup. Moreover, it advances the throughput of reading and writing by making the NFS system function invoked from the inside of the filesystem. We developed this filesystem, and evaluated the performance from the viewpoint of throughput, system call speed and CPU loads. The results show that there is no problem in the viewpoint of the performance compared with the conventional filesystem, and the throughput of the read and write of GMFS is 2.0 times faster than conventional mirroring filesystem.