2 research outputs found
A Note on the Transformation to Enable Optimal Repair in MDS Codes for Distributed Storage Systems
For high-rate maximum distance separable (MDS) codes, most early
constructions can only optimally repair all the systematic nodes but not for
all the parity nodes initially. Fortunately, this issue was firstly solved by
Li et al. in (IEEE Trans. Inform. Theory, 64(9), 6257-6267, 2018), where a very
powerful transformation that can convert any nonbinary MDS code into another
MDS code with desired properties was proposed. However, the transformation does
not work for binary MDS codes. In this note, we address this issue by proposing
another generic transformation that can convert any (n, k) binary MDS code into
a new binary MDS code, which endows any r=n-k chosen nodes with the optimal
repair bandwidth and the optimal rebuilding access properties, and at the same
time, preserves the normalized repair bandwidth and the normalized rebuilding
access for the remaining k nodes under some conditions. As two immediate
algorithms of this transformation, we show that 1) by applying the
transformation multiple times, any (n,k) binary MDS code can be converted into
an (n,k) binary MDS code with the optimal repair bandwidth and the optimal
rebuilding access for all nodes, 2) any binary MDS code with the optimal repair
bandwidth or the optimal rebuilding access for the systematic nodes only can be
converted into an MDS code with the corresponding repair optimality for all
nodes.Comment: 17 page
Multi-Layer Transformed MDS Codes with Optimal Repair Access and Low Sub-Packetization
An maximum distance separable (MDS) code has optimal repair access if
the minimum number of symbols accessed from surviving nodes is achieved,
where . Existing results show that the sub-packetization
of an high code rate (i.e., ) MDS code with optimal
repair access is at least . In this
paper, we propose a class of multi-layer transformed MDS codes such that the
sub-packetization is , where
, and the repair access is optimal for
any single node. We show that the sub-packetization of the proposed multi-layer
transformed MDS codes is strictly less than the existing known lower bound when
, achieving by restricting the choice
of specific helper nodes in repairing a failed node. We further propose
multi-layer transformed EVENODD codes that have optimal repair access for any
single node and lower sub-packetization than the existing binary MDS array
codes with optimal repair access for any single node. With our multi-layer
transformation, we can design new MDS codes that have the properties of low
computational complexity, optimal repair access for any single node, and
relatively small sub-packetization, all of which are critical for maintaining
the reliability of distributed storage systems