MagicStore: A New Out-of-Band Virtualization System in SAN Environments

In this paper, MagicStore, a new out-of-band virtualization system designed for SAN environments is proposed. Online multiplication of the components in a striped volume can help enhance both the I/O performance and storage capacity of a system, but it requires online redistribution of the data on the volume. MagicStore employs a new mapping management solution based on a sliding window to support the online data redistribution without loss of scalability. Furthermore, some virtualization transactions, such as online resizing, require modification of the virtualization metadata, which results in the challenge of keeping the persistent consistency of metadata. MagicStore, by using a combination of ordered writes, REDO logging and log integrity checking, can survive across panics and power failures robustly. In order to support log integrity checking effectively, MagicStore also uses a new log format.