Dynamic allocation and data distribution in networked storage systems

存储设备现在可以连接到主机、服务器、存储区域网络（SAN）和局域网/广域网（LAN/WAN）。设备附件的这种激增导致了存储的灵活部署以及跨多个主机和操作系统的存储池和共享。但是，本机文件系统（如Windows XP或Linux Ext 2）希望独占访问其存储卷。换句话说，每个操作系统都保留存储设备供其使用，并且一个操作系统所拥有的存储设备中的空间不能被另一个操作系统使用。这种静态分配严重妨碍了存储空间的共享。这种灵活性的缺乏也阻碍了“效用计算”模型，在这种模型中，用户可以根据资源的使用情况收费。 这种缺乏灵活性的情况也限制了组织不同部门之间的存储资源共享。本项目计划设计和开发存储系统中的“虚拟分配”或“按需分配”。虚拟分配将采用写时分配策略，即，当写入数据时分配存储空间。这种方法将存储空间分配与文件系统大小分离，并允许创建具有许多新颖功能的虚拟存储系统。该项目将探讨与性能，设备特性，局部性和并行性在采用虚拟分配的体系结构问题。该项目将调查虚拟分配是否可以实现跨共享网络存储设备的动态数据重新分配或迁移，以便在不断变化的工作负载和使用模式中平衡本地性和负载。 该项目将调查虚拟分配是否可以通过在低需求时将数据集中到较少数量的设备上来实现节能。

The storage devices now can be connected to hosts, servers, Storage Area Networks (SANs) and Local/Wide-area Networks (LANs/WANs). This proliferation of device attachments leads to flexible deployment of storage and potential pooling and sharing of storage across multiple hosts and operating systems. However, native file systems, such as Windows NTFS or Linux Ext2, expect to have exclusive access to their storage volumes. In other words, each operating system reserves storage devices for its use, and the space in a storage device owned by one operating system cannot be used by another. This static allocation seriously hampers the sharing of storage space. This lack of flexibility also hampers "utility computing" models where users can be charged based on usage of resources. This lack of flexibility also limits the sharing of storage resources across different divisions of an organization. This project plans to design and develop "virtual allocation" or "on-demand allocation" in storage systems. Virtual allocation will employ allocate-on-write policy i.e., storage space is allocated when the data is written. Such an approach separates the storage space allocation from the file system size and allows creation of virtual storage systems with many novel features. The project will explore architectural issues related to performance, device characteristics, locality and parallelism in employing virtual allocation. The project will investigate if virtual allocation can enable dynamic data redistribution or migration across shared networked storage devices in order to balance locality and load across changing workloads and usage patterns. The project will investigate if virtual allocation can enable power savings by pooling data onto a smaller number of devices at times of low demand.