A publication of ISCA * : International Society for Computers and Their Applications INTERNATIONAL JOURNAL OF COMPUTERS AND THEIR APPLICATIONS

The possibility to migrate a virtual server from one physical computer in a cloud to another physical computer in the same cloud is important in order to obtain a balanced load. In order to facilitate live migration of virtual servers, one needs to provide large shared storage systems that are accessible for all the physical servers that are used in the cloud. Distributed storage systems offer reliable and cost-effective storage of large amounts of data and such storage systems will be used in future Cloud Computing. We have evaluated four large distributed storage systems. Two of these use Distributed Hash Tables (DHTs) in order to keep track of how data is distributed, and two systems use multicasting to access the stored data. We measure the read/write/delete performance, as well as the recovery time when a storage node goes down. The evaluations are done on the same hardware, consisting of 24 storage nodes and a total storage capacity of 768 TB of data. These evaluations show that the multicast approach outperforms the DHT approach.