Abstract: A data network includes a switch that links a number of host processors to shared resources such as network ports of a cached storage subsystem. The switch routes resource requests from its inputs to selected ones of its outputs in accordance with programmed routing information. The routing information is changed dynamically based on measured loading characteristics of requests from the switch inputs or the respective hosts, in order to reduce the probability of blocked paths. In a specific example, respective subsets of output ports of the switch are assigned to each respective input port, the loading of each input port of the switch is measured, and the respective subset of output ports assigned to each input port are repetitively changed, and the respective subset of an input port is changed in response to blocking of the output ports assigned to the input port.

Abstract: A method and apparatus for accessing storage from at least two different host computers features creating a first file having a first meta-data format and user data blocks in a mass storage medium using the first host computer and reading a logical to physical mapping of the user data blocks from the first file. A second file, having a second meta-data format, is created using a second host computer and the second file has blocks preallocated to be the same length as user data blocks of the first file. A logical to physical mapping of the preallocated user blocks is then obtained and the data blocks of the preallocated file are linked to the data blocks of the first file so that a reference to the preallocated blocks will provide an address at which the data requested can be read in the first file. In this manner, different meta-data blocks, corresponding to different filesystems, and/or operating systems, can be used in the respective first and second host computers.