Method and system for arbitrating computer access to a shared storage medium using SCSI protocol
AssigneeDigital Multitools, Inc.
InventorPeter D. Gray
Life of this patent
Estimating the term…
Abstract
A method of arbitrating access to a storage medium that is shared by M first computers operating on a Windows™ operating comprising (1) determining if the SCSI PR-flag has been set; (2) if yes, preventing the N second computers from writing to the storage medium; and (3) setting the SCSI MC-flag for each of said M first computers after one of the second computers writes to the storage medium to notify the M first computers that the contents of the storage medium may have changed.
Claims13
A method of arbitrating access to a storage medium that is shared by M first computers operating on a WINDOWS operating system, M≧1, and N second computers, N≧1, the method comprising the steps of:
- determining, by a device, if SCSI (Small Computer Systems Interface) PR-flag (Prevent-remove flag) has been set;
- if the SCSI PR-flag has been set, preventing the N second computers from writing to the storage medium;
- setting, by a storage medium drive, a SCSI MC-flag (media-change flag) for each of said M first computers after one of the second computers writes to the storage medium using SCSI protocol;
- notifying the M first computers that contents of the storage medium have changed based on the SCSI MC-flag used by the SCSI protocol;
- delaying a write to the storage medium by the one of the N second computers for a timeout period when the PR-flag is set;
- and
- causing said write to fail if the timeout period has passed and the PR-flag is still set.
A system for arbitrating access to a storage medium that is shared by M first computers operating on a WINDOWS operating system, M≧1, and N second computers, N≧1, the system comprising:
- a device for (a) determining if the SCSI (Small Computer Systems Interface) PR-flag (Prevent-remove flag) has been set, and if the SCSI PR-flag has been set, preventing the N second computers from writing to the storage medium;
- for (b) setting a SCSI MC-flag (media-change flag) for each of said M first computers after one of the second computers writes to the storage medium using SCSI protocol, and for (c) notifying the M first computers that contents of the storage medium have changed based on the SCSI MC-flag used by the SCSI protocol;
- a first link to operatively connect the device to the N second computers;
- the device further being configured to delay a write to the storage medium by the N second computers for a timeout period when the PR-flag is set and to cause said write to fail if the PR-flag is still set when the timeout period has passed;
- and
- a second link to operatively connect the M first computers to the device.
Dependencies are inferred from the claim text.