Design of error correction systems for disk drives

Certain models are presented for analysis of Reed-Solomon (R-S) error correction systems in the context of optimizing their use in magnetic and optical disk storage devices. A brief statement of design considerations is noted with references as to which considerations are addressed by the models. This work is motivated by the desire to achieve the highest possible storage density within the constraints of user requirements (acceptable error rates, performance, etc.), recording code, recording channel, read channel, and cost. One pair of models treats conversion of soft error rates and burst length distributions from the read channel into hard bit error rates for various levels of interleaving. Another model, using the above models, conservatively estimates undetected bit error rate (miscorrection bit error rate). This model is closer to simulation examples than the previously published McEliece-Swanson bound. A third model includes effect of TAs (thermal asperities) on hard bit error rate. A fourth set of models includes the effect of thermal asperities (TAs) on an undetected bit error rate. Collectively, these models provide a bridge between read channel portions of data storage systems and error correction systems. A fifth set of models addresses user-perceived performance. Finally, an example is offered based upon one set of sample data to show how the models can be applied to help select an optimum system.