No abstract

Metadata plays an important role in mass storage system. How to distribute and balance the metadata of the metadata server cluster determines the overall performance of a cluster. Two popular metadata distribution policies are the dynamic subtree policy and hashing policy, while the dynamic subtree partition is vulnerable to the imbalance workload and hashing partition has a random distribution which will incur a burst of network overhead when updating metadata.We present a novel approach for metadata management. It combines hash and subtree partitioning policies together to partition directory hierarchy tree into equipotent subtrees with a certain granularity and employs value of hashing subtree to distribute subtrees across the metadata servers. It also employs a balance strategy to adjust the metadata distribution dynamically. After adjustment, we present a hot spots elimination strategy to detect and reclaim hot spots in the file system efficiently. We also demonstrate a design using this strategy to achieve more efficient performance than the other policies using hashing partitioning and subtree partitioning purely.

Using appropriate method to manage object attributes can evidently improve the performance of object-based storage system. At present, object attributes are managed by object based file system (OBFS) and stored in fixed data structure. This method has limitation in expansibility and increases the workloads of the OBFS. In this paper, we will put forward B+ tree management method of object attributes. The experiment results show that if we use the traditional method to manage the object attributes, the performance of the storage system descend quickly with the number of the object attributes operation request increasing, but if we use the B+ tree management method, the performance of the storage system retains steady.

This paper explores the shingled writing head designs for making 10 patterned media data storage more feasible. The relationship between the writing ability improvement of the shingled writing head and the tip width is discussed. The results reveal that a small rounded corner design would be beneficial for improving the writing performance of the writing head. A corner gap, which is slightly smaller than the shield gap, will give the best writing performance.