International Business Machines Corporation

Nicholas S Ham

Sanket Rathi

Kiran Kumar Anumalasetty

Sudhir Maddali

Stephen M Tee

Yadagiri Rajaboina

Purna Chandra Jasti

James P Allen

John Leslie Neemidge

Carol Santich Mellgren

Jared Michael Minch

Gary Steven Domrow

Jeffrey Michael Barnes

A method is disclosed for retrieving the reservation status information of a storage area network (SAN) device, a host transmits a persistent reservation in command with service action setting of 'read reservation' to a first LUN, wherein the host is connected to a port of the data storage server to which the LUN belongs. The host receives a message from the LUN. The host determines that the message is a success. The host sends to the LUN a persistent reservation in command with service action setting of 'read keys', responsive to a success message. The host determines that the LUN responds with a zero data length. The host determines the LUN is reserved with type 2 reservation, responsive to a determination that the LUN responds with a non-zero data length.

SCSI reservation status information on a SAN disk

Techniques for switching between mirrored volumes are described. A system may comprise a multi-path device driver and a processor device, in communication with the multi-path device driver, operable in the computing storage environment. The processor device creates a copy relation identification (ID) between mirrored volumes for using the copy relation ID in conjunction with a multi-path device driver for switching input/output (I/O) for applications between a first path to a second path between the mirrored volumes.

Switching between mirrored volumes

A system and computer program product are disclosed for retrieving the reservation status information of a storage area network (SAN) device, a host transmits a persistent reservation in command with service action setting of 'read reservation' to a first LUN, wherein the host is connected to a port of the data storage server to which the LUN belongs. The host receives a message from the LUN. The host determines that the message is a success. The host sends to the LUN a persistent reservation in command with service action setting of 'read keys', responsive to a success message. The host determines that the LUN responds with a zero data length. The host determines the LUN is reserved with type 2 reservation, responsive to a determination that the LUN responds with a non-zero data length.

Disclosed is a computer implemented method and apparatus for queuing I/O requests to a pending queue. The I/O device driver sets a maximum ordered queue length for an I/O device driver coupled to a storage device then receives an I/O request from an application. The I/O device driver determines whether the pending queue is sorted and responds to a determination that the pending queue is sorted, determining if queued I/O requests exceed the maximum ordered queue length. Responding to a determination that the pending queue exceeds the maximum ordered queue length, the I/O device driver adds the I/O request based on a high pointer, and points the high pointer to the I/O request.

Transitions between ordered and ad hoc I/O request queueing

Growing community of inventors

Austin, TX, United States of America

Nicholas S Ham