LAUSR

Regenerating codes (RGCs) have recently been proposed to reduce the repair traffic of ( $n,k$ ) erasure-coded distributed storage systems. Moreover, RGCs can also be used in a scalable distributed storage scenario where $n$ is increased (decreased) to upgrade (degrade) redundancy while maintaining the maximum distance separable property of erasure codes. In this paper, we propose a new application of minimum storage regenerating (MSR) codes in storage scalability. The connection between repairing invalid nodes and adding new nodes suggests that the two processes can be unified in the same framework. We consider both single and multiple node situations, and two methods for constructing multiple nodes are proposed: concurrent and sequential. We focus on proving the achieved capability of concurrent MSR that can consume minimum traffic for generating multiple nodes. Because concurrent MSR is sensitive to both the number of helpers and added nodes, sequential methods make scalable MSR generalizable. The examples show that the scalable MSR codes have the same advantage of saving network traffic as repairing failures.