Patent ID: 6041394
Filing Date: 2000-03-21
Classification: G06F

Abstract:
In a system having a plurality of host computers and at least one mass storage device having a controller for accessing a plurality of logical volumes, at least one of said logical volumes being able to be written to by at least two of said hosts at different controller ports, a method for changing the write protect status of a said logical volume comprising the steps ofobtaining control of a write protect lock, in response to a host request, from a first host, for a change in write protect status for at least one selected logical volume,writing, in response to said first host, a write protect message to a logical volume memory location associated with each logical volume to be affected,setting a flag message in a message memory location indicating a change in said logical volume memory location,polling the message memory location for set flag messages,writing, in response to a set flag message, in a local memory associated with the controller port associated with the requesting host, a status of at least all logical volumes accessible from said port, andpreventing, at the controller, a host from writing to a protected logical volume as identified by data in the said controller's local memory.