HiSMRfs: A high performance file system for shingled storage array

HiSMRfs a file system with standard POSIX interface suitable for Shingled Magnetic Recording (SMR) drives, has been designed and developed. HiSMRfs can manage raw SMR drives and support random writes without remapping layer implemented inside SMR drives. To achieve high performance, HiSMRfs separates data and metadata storage, and manages them differently. Metadata is managed using in-memory tree structures and stored in a high performance random write area such as in a SSD. Data writing is done through sequential appending style and store in a SMR drive. HiSMRfs includes a file/object-based RAID module for SMR/HDD arrays. The RAID module computes parity for individual files/objects and guarantees that data and parity writing are 100% in sequential and in full stripe. HiSMRfs is also suitable for a hybrid storage system with conventional HDDs and SSDs. Two prototype systems with HiSMRfs have been developed. The performance has been tested and compared with SMRfs and Flashcache. The experimental tests show that HiSMRfs performs 25% better than SMRfs, and 11% better than Flashcache system.