Control of a multi-user disk storage system

A method and apparatus control operation of a disk drive array system which is accessible to a plurality of host computers over a SCSI bus. In accordance with the invention, an Inquiry command, configured to set a global semaphore or hardware lock for reserving exclusive control of the disk array, is sent to the disk system over the SCSI bus from a first host system. The disk drive system responds to the Inquiry command by setting the global semaphore if the global semaphore has not already been set. The disk drive system stores an identification of the host which sets the semaphore and reserves exclusive use of the control functions on the disk drive system for that host. The disk drive system then sends an Inquiry command response back to the host identifying a current holder of the semaphore. The host can also send other commands inquiring of the identity of the owner of the global semaphore, releasing its ownership of the global semaphore, and, if a maximum available predetermined time interval has passed, forcing either the reservation or release of the global semaphore. In this manner, synchronized use of the control functions of the disk drive system is maintained even though the host computers might otherwise have been able to corrupt or interfere with each other's competing applications and accesses.