4,337,518 6/1982 Ohnishi et al. ................. 364/724.7 4,377.806 3/1983 Elliott et al. ... ... 341/101 4,517,659 5/1985 Chamberlain ... 395/800 4,794,627 12/1988 Grimaldi .......... ... 375/14 4,799,152 1/1989 Chuang et al. ... 395/800 4,799,182 1/1989 Marwood ......... ... 364/748 4,910,700 3/1990 Hartley et al. ... ... 364/754 4,942,396 7/1990 Hartley et al. ... .341/10 5,025,257 6/1991 Hartley et al. ...................... 34/101 5,034,908 7/1991 Hartley et al. ................. 364/724.16

RAID triple parity (RTP) is a new algorithm for protecting against three-disk failures. It is an extension of the double failure correction Row-Diagonal Parity code. For any number of data disks, RTP uses only three parity disks. This is optimal with respect to the amount of redundant information required and accessed. RTP uses XOR operations and stores all data un-encoded. The algorithm's parity computation complexity is provably optimal. The decoding complexity is also much lower than that of existing comparable codes. This paper also describes a symmetric variant of the algorithm where parity computation is identical to triple reconstruction.

MAPL is a journaling file system providing advanced data management features like snapshots and clones. It is also designed to show read/write performance near that of raw disk access for both random and sequential access patterns. Further, the system is designed to show stable I/O performance over time, regardless of the workload placed on it. Important goals of the design are that MAPL seeks to make I/O to the active file system behave like I/O to a LUN on a hardware-based RAID array, while minimizing performance overhead caused by snapshots. Specifically, MAPL minimizes the effects on write activity of snapshot creation, as well as the effects of the presence of snapshots on ongoing I/O. Like the frame arrays it mimics, MAPL is optimized for large files, and its performance goals center on them.

Hybridization and introgression between introduced and native salmonids threaten the continued persistence of many inland cutthroat trout species. Environmental models have been developed to predict the spread of introgression, but few studies have assessed the role of propagule pressure. We used an extensive set of fish Stocking records and geographic information system (GIS) data to produce a spatially explicit index of potential propagule pressure exerted by introduced rainbow trout in the Upper Kootenay River, British Columbia, Canada. We then used logistic regression and the information-theoretic approach to test the ability of a set of environmental and spatial variables to predict the level of introgression between native westslope cutthroat trout and introduced rainbow trout. Introgression was assessed using between four and seven co-dominant, diagnostic nuclear markers at 45 sites in 31 different streams. The best model for predicting introgression included our GIS propagule pressure index and an environmental variable that accounted for the biogeoclimatic zone of the site (r2=0.62). This model was 1.4 times more likely to explain introgression than the next-best model, which consisted of only the propagule pressure index variable. We created a composite model based on the model-averaged results of the seven top models that included environmental, spatial, and propagule pressure variables. The propagule pressure index had the highest importance weight (0.995) of all variables tested and was negatively related to sites with no introgression. This study used an index of propagule pressure and demonstrated that propagule pressure had the greatest influence on the level of introgression between a native and introduced trout in a human-induced hybrid zone.