  In this paper, we show that coding can be used in storage area networks
(SANs) to improve various quality of service metrics under normal SAN operating
conditions, without requiring additional storage space. For our analysis, we
develop a model which captures modern characteristics such as constrained I/O
access bandwidth limitations. Using this model, we consider two important
cases: single-resolution (SR) and multi-resolution (MR) systems. For SR
systems, we use blocking probability as the quality of service metric and
propose the network coded storage (NCS) scheme as a way to reduce blocking
probability. The NCS scheme codes across file chunks in time, exploiting file
striping and file duplication. Under our assumptions, we illustrate cases where
SR NCS provides an order of magnitude savings in blocking probability. For MR
systems, we introduce saturation probability as a quality of service metric to
manage multiple user types, and we propose the uncoded resolution- aware
storage (URS) and coded resolution-aware storage (CRS) schemes as ways to
reduce saturation probability. In MR URS, we align our MR layout strategy with
traffic requirements. In MR CRS, we code videos across MR layers. Under our
assumptions, we illustrate that URS can in some cases provide an order of
magnitude gain in saturation probability over classic non-resolution aware
systems. Further, we illustrate that CRS provides additional saturation
probability savings over URS.
