Rack-Aware MSR Codes With Optimal Access for Multiple Sequentially Ordered Node Failures

The minimum storage rack-aware regenerating (MSRR) code is a variation of regenerating codes that achieves the optimal repair bandwidth for a single node failure within the rack-aware model. We study the access complexity of repairing MSRR codes, that allows collective information processing among nodes within the same rack. A previous study has reported construction of MSRR codes that require accessing the minimum number of symbols to repair a single node. We extend this work by constructing a family of MSRR codes that minimizes the number of symbols accessed to repair sequentially ordered failed nodes in a single rack, and further show that for certain code parameters, another version of MSRR codes can be constructed with reduced sub-packetization while still preserving the optimal access property.