具有可用性改善的P-Grid覆盖网络

Availability Improved P-Grid Overlay Network

原P-Grid覆盖网络通过大量冗余将低在线率的节点构建成高可用性的系统.考虑分布式环境下节点不一定具有低在线率而呈现周期性,提出一种基于P-Grid的具有可用性改善的节点周期性组织方式.分类节点为长期节点、周期节点和普通节点,将长期节点按原P-Grid方式形成周期性组织下的主体二叉树,设计适当的信息表结构建立节点间的关系,并给出相应的查找、节点加入和数据对象创建的算法.数值分析和模拟实验表明在相同的节点规模及树高度下,周期性组织方式可以达到更高的可用性,同时数值分析也表明不影响维护消耗.

In original P-Grid overlay network,a large number of peers with low availability are organized to form high availability system.Considering peers in distributed environment do not always have low availability but show periodical feature,an availability improved P-Grid with periodical organization is presented.Peers are categorized into three types,that is Long Term Peer（LTPeer）,Periodical Peer（PPeer）,Normal Peer（NPeer）.LTPeer is organized as main body binary tree with original P-Grid style.Suitable information tables are designed to establish relations among LTPeer,PPeer and NPeer.Algorithms about search,join of peer and register of data object are proposed accordingly.Numerical analyses show that in the same number of peers and the same height of tree,periodical organization can reach higher availability and does not affect maintenance cost.