Load Balancing with SCSI I/O Referrals

Abstract

A method and/or system may be configured to receive an input/output (I/O) request from an initiator system, add priority information to a multiple path referral for each port on which data can be accessed, selectively omit ports on which data may be accessed, transmit the multiple path referral from the target to the initiator, and/or choose a path on the initiator with the highest performance.

What is claimed is: 
     
         1 . A method for communication between an initiator system and a block storage cluster, comprising:
 receiving an input/output (I/O) request from the initiator system on a target, the input/output (I/O) request associating data for transfer to or transfer from a storage location, such data accessible by two or more ports, each of the two or more ports controlled by one of two or more controllers;   adding priority information to a multiple path referral for each port on which data can be accessed, where the priority information includes a plurality of relative performances for accessing data via a plurality of specific ports accessible by a plurality of initiators; and   selectively omitting one or more ports on which data could be accessed from the multiple math referral to prohibit an initiator from accessing data via those one or more ports, wherein selectively omitting the one or more ports temporarily shifts a load to at least one other port on which data can be accessed.   
     
     
         2 . The method of  claim 1 , wherein adding priority information to a multiple path referral for each port on which data can be accessed, where the priority information includes a relative performance for accessing data via at least one specific port, comprises:
 adding priority information to a port priority field associated with each port.   
     
     
         3 . The method of  claim 1 , further comprising transmitting referral information including information regarding a port controlled by another controller. 
     
     
         4 . The method of  claim 1 , further comprising dynamically updating the multiple path referral. 
     
     
         5 . The method of  claim 1 , further comprising transmitting an indication of at least one of data moved by the storage cluster and changed referral information. 
     
     
         6 . The method of  claim 5 , wherein transmitting an indication of at least one of data moved by the storage cluster and changed referral information comprises:
 updating an initiator referral cache.   
     
     
         7 . The method of  claim 1 , further comprising choosing a path with lower performance to access data for fault tolerance when no higher performance path is available. 
     
     
         8 . The method of  claim 1 , further comprises:
 receiving an input/output (I/O) request from the initiator system, the input/output (I/O) request associating data for at least one of transfer to and transfer from a volume segment;   adding priority information to a multiple path referral for each port on which data can be accessed, where the priority information includes a relative performance for accessing data via at least one specific port;   transmitting a multiple path referral from at least one target to an initiator system, where the multiple path referral includes the priority information; and   choosing a path on the initiator system with a highest performance indicated by priority information in a multiple path referral.   
     
     
         9 . The method of  claim 1 , wherein the two or more controllers are organized into one or more virtual volumes. 
     
     
         10 . A storage system, comprising:
 means for receiving an input/output (I/O) request from an initiator system, the input/output (I/O) request associating data for transfer to or transfer from a storage location, such data accessible by two or more ports, each of the two or more ports controlled by one of two or more controllers;   means for adding priority information to a multiple path referral for each port on which data can be accessed, where the priority information includes a plurality of relative performances for accessing data via a plurality of specific ports accessible by a plurality of initiators; and   means for selectively omitting one or more ports on which data could be accessed from the multiple math referral to prohibit an initiator from accessing data via those one or more ports, wherein selectively omitting the one or more ports temporarily shifts a load to at least one other port on which data can be accessed.   
     
     
         11 . The storage system of  claim 10 , further comprising means for transmitting referral information including information regarding a port controlled by another controller. 
     
     
         12 . The storage system of  claim 10 , wherein means for receiving an input/output (I/O) request from the initiator system, the input/output (I/O) request associating data for transfer to or transfer from a storage location, comprises:
 means for transmitting an indication of at least one of data moved by the storage cluster and changed referral information.   
     
     
         13 . The storage system of  claim 10 , wherein means for receiving an input/output (I/O) request from the initiator system, the input/output (I/O) request associating data for transfer to or transfer from a storage location, comprises:
 means for adding priority information to a port priority field associated with each port.   
     
     
         14 . The storage system of  claim 10 , further comprising means for choosing a path with a highest performance. 
     
     
         15 . The storage system of  claim 10 , wherein the two or more controllers are organized into one or more virtual volumes. 
     
     
         16 . A system, comprising:
 a computing device; and   instructions that when executed on the computing device cause the computing device to:
 receive an input/output (I/O) request from an initiator system, the input/output (I/O) request associating data for transfer to or transfer from a storage location, such data accessible by two or more ports, each of the two or more ports controlled by one of two or more controllers; 
 add priority information to a multiple path referral for each port on which data can be accessed, where the priority information includes a plurality of relative performances for accessing data via a plurality of specific ports accessible by a plurality of initiators; and 
 selectively omit one or more ports on which data could be accessed from the multiple math referral to prohibit an initiator from accessing data via those one or more ports, wherein selectively omitting the one or more ports temporarily shifts a load to at least one other port on which data can be accessed. 
   
     
     
         17 . The system of  claim 16 , wherein the computing device comprises at least one of a laptop computer, at least one processor, at least one server, a workstation computer, or a desktop computer. 
     
     
         18 . The system of  claim 16 , wherein the data storage location comprises a plurality of data storage devices, each of the one or more data storage devices connected to at least one of the one or more ports, organized into one or more virtual volumes. 
     
     
         19 . The system of  claim 18 , wherein at least one of the two or more controllers comprises a virtualization layer. 
     
     
         20 . The system of  claim 18 , wherein the instructions further cause the computing device to transmit an indication of at least one of data moved between the one or more virtual volumes and changed referral information.