(1) A software mechanism that the ESS uses to request that an operating system of a zSeries or S/390 host verify that one or more subsystem resources can be taken offline for service. The ESS can use this process to automatically vary channel paths offline and online to facilitate bay service or concurrent code installation. Depending on the operating system, support for this process might be model-dependent, might depend on the IBM TotalStorage Enterprise Storage Server Subsystem Device Driver, or might not exist.
(2) An automation of the process used by service representatives to vary off and vary on subsystem resources for maintenance.