Hewlett-packard Development Company, L.p.

Rajkumar Mangalore

Vijay Srinath

Vikram Krishnamurthy

Subramaniyam V Pooni

The method and apparatus is utilized in order to generate a persistent path to a SCSI device for a host. In an embodiment, a SCSI device is queried for path information related thereto, and if path information is returned, a SCSI command requesting identifier data is issued to the SCSI device. The identifier data is used to determine a unique identifier (UID), from which is generated a UID-based device file for the SCSI device that is independent from the path information.

Method and apparatus for generating persistent path identifiers

A method, by which a user mode application obtains all physical paths that point to a logical unit on a newly-discovered small computer system interface (SCSI) device, may include: sending an input output control command to a kernel component regarding future discovery of any SCSI device; awaiting discovery of a new SCSI device; awaiting generation, by the kernel component, of a unique identifier (UID) and at least one set of physical path information mapping thereto for a logical unit on the newly-discovered SCSI device; and receiving, from the kernel component, the UID and the at least one set of physical path information mapping thereto for the logical unit of the newly-discovered SCSI device.

Method and apparatus for identifying multiple paths to discovered SCSI devices and specific to set of physical path information

The method includes querying for one or more logical unit numbers (LUNs) pertaining to a small computer system interface device, each LUN representing a potential path from a host to the SCSI device. Response data indicative of multiple LUNs to the single SCSI device is treated as separate instances of independent SCSI devices, with each separate instance representing a different SCSI separate instances of independent SCSI devices, with each separate instance representing a different SCSI device structure. A unique identifier (UID) is calculated for each SCSI device structure, from which a device file is generated based on the UID and contains UID and path information that differentiates between multiple paths from the host to the SCSI device.

Method and apparatus for identifying multiple paths to a SCSI device using a calculated unique identifier

A method and arrangement, for use in a system having a host and one or more small computer system interface (SCSI) devices, are described for enabling a user application accessing the system to communicate with one or more of the SCSI devices. The method and arrangement serve to overcome a device node limitation observed in standard Linux, which limits the number of devices a user application may communicate with to 128 SCSI disk (sd) devices or 256 SCSI generic (sg) devices. The method and arrangement provide a pass through capability by allowing the user application to directly talk to any SCSI device by using virtual handles, thereby overcoming the device node limitation observed in standard Linux.

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Bengaluru, India

Rajkumar Mangalore