Methods and structure for supporting persistent reservations in a multiple-path storage environment
First Claim
Patent Images
1. A system comprising:
- at least one host system wherein each host system has multiple SCSI-3 I/O adapters serving as SCSI-3 initiators for coupling the corresponding host system to a storage system and wherein the multiple SCSI-3 I/O adapters define multiple physical paths between the corresponding host system and a storage system;
at least one process operable on each of said at least one host system wherein each process is adapted to generate a host system request to exchange information with a storage system and wherein the generated host system requests use virtual path information representing any of the multiple physical paths between the corresponding host system and a storage system without indicating a specific physical path of the multiple physical paths; and
a multiple-path driver element configured within each of said at least one host system and coupled to each said process to map virtual path information into physical path information for a selected physical path of the multiple physical paths and wherein the multiple-path driver is further adapted to transparently coordinate SCSI-3 Persistent Reservation operations by all processes operable on all host systems of the system.
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Abstract
A persistent reservation emulation structure to emulate exclusive reservation SCSI-3 protocol features in a host system having multiple paths to a storage device. An enhanced multiple-path driver layer (or other processing elements) provide emulation of persistent reservation commands directed from a host system to a storage device. The driver does not forward exclusive type reservations to the storage device but rather emulates the desired exclusive operations on the systems behalf using only non-exclusive reservation types. The emulated reservation handling enables parallel use of multiple paths between a host system and a storage device to improve reliability and/or performance of the storage device.
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Citations
19 Claims
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1. A system comprising:
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at least one host system wherein each host system has multiple SCSI-3 I/O adapters serving as SCSI-3 initiators for coupling the corresponding host system to a storage system and wherein the multiple SCSI-3 I/O adapters define multiple physical paths between the corresponding host system and a storage system; at least one process operable on each of said at least one host system wherein each process is adapted to generate a host system request to exchange information with a storage system and wherein the generated host system requests use virtual path information representing any of the multiple physical paths between the corresponding host system and a storage system without indicating a specific physical path of the multiple physical paths; and a multiple-path driver element configured within each of said at least one host system and coupled to each said process to map virtual path information into physical path information for a selected physical path of the multiple physical paths and wherein the multiple-path driver is further adapted to transparently coordinate SCSI-3 Persistent Reservation operations by all processes operable on all host systems of the system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A computer readable storage medium tangibly embodying programmed instructions that when executed by a computer perform functions of an improved multiple-path driver operable in a host system for adapting application storage requests directed to a virtual path for exchange with a storage system over multiple physical paths between the host system and the storage system, the programmed instructions operable to perform an improvement of the multiple-path driver comprising:
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a Persistent Reservation command processing element to process SCSI-3 Persistent Reservation commands received from the host system and directed to a virtual path by transmitting translated Persistent Reservation commands applied to multiple physical paths of a host system; and a filter processing element to process other SCSI-3 commands in accordance with the translated Persistent Reservation command processing. - View Dependent Claims (10, 11, 12, 13)
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14. A method operable in a host system having multiple physical paths coupling it to a storage system, the method comprising:
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receiving SCSI-3 commands from a process in the host system directed to the storage system over an identified path of the multiple physical paths; processing received SCSI-3 Persistent Reservation commands to coordinate SCSI-3 Persistent Reservation commands generated by the process applied to any of the multiple possible physical paths; and filtering other received SCSI-3 commands to emulate operation of the SCSI-3 Persistent Reservation protocol for all physical paths between the host system and the storage device. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification