RAID Level 6 and Level 6+ Reliability

Storage systems are built of fallible components but have to provide high degrees of reliability. Besides mirroring and triplicating data, redundant storage of information using erasure-correcting codes is the only possibility to have data survive device failure. We provide here exact formula for the data-loss probability of a disk array composed of several RAID Level 6 stripes. This two-failure tolerant is not only used in practice but can also provide a reference point for the assessment of other data organizations

Band-stop filter based on a metal/insulator-disk array/metal structure

We describe a band-stop filter based on a periodic dielectric-disk array inserted into a metal–insulator–metal (MIM) waveguide. We use finite-difference time-domain (FDTD) methods to study the characteristics of our proposed structure. The results show that there is a flat stop band in the transmission spectrum, in which the transmission is close to zero. The central wavelength of the filter can be controlled by adjusting the lattice constant of the disk array. We discuss the maximum bandwidth and provide a set of parameters suitable for designing a band-stop filter that has a flat stop band-width of approximately 400 nm and a superior on/off ratio. Our structure has potential applications in the design of nanoscale optical devices.