Generating monotone hash preferences

Abstract

Selecting a resource to fulfill a resource requirement is disclosed. For each resource requirement, a resource-specific affinity value is computed with respect to each of a plurality of resources. A bias is applied to each of at least a subset of the resource-specific affinity values. The biased, as applicable, resource-specific affinity values are sorted into a resource preference list. The sorted preference list is used to select a resource to fulfill the resource requirement.

What is claimed is: 
     
         1 . A resource selection system, comprising:
 a communication interface configured to receive a communication comprising an operation associated with a data object; and   a processor coupled to the communication interface and configured to:
 compute for each of a plurality of resources, with respect to the data object, a resource-specific affinity value; 
 apply a bias to each of at least a subset of the resource-specific affinity values, wherein the bias comprises a function that is monotonically increasing; and 
 use the resource-specific affinity values to select a resource to fulfill the operation associated with the data object. 
   
     
     
         2 . The system of  claim 1 , wherein the function is monotonically increasing in terms of one or more of an input hash and a desired bias. 
     
     
         3 . The system of  claim 1 , wherein the bias comprises a resource-specific bias. 
     
     
         4 . The system of  claim 1 , wherein the bias comprises a resource-specific bias determined for a particular resource based at least in part on a data associated with that particular resource. 
     
     
         5 . The system of  claim 1 , wherein the bias is determined based at least in part on a data associated with the operation. 
     
     
         6 . The system of  claim 1 , wherein the bias is determined for a particular resource based at least in part on a data reflecting a relationship between the data object and the particular resource. 
     
     
         7 . The system of  claim 6 , wherein the bias is determined based at least in part on a stored data reflecting a past relationship between the resource and the data object. 
     
     
         8 . The system of  claim 6 , wherein the bias is determined based at least in part on a stored data reflecting a past relationship between the resource and a user with which the operation is associated. 
     
     
         9 . The system of  claim 1 , wherein the bias comprises a multiplicative bias. 
     
     
         10 . The system of  claim 1 , wherein the operation is associated with storing the data object. 
     
     
         11 . The system of  claim 1 , wherein the operation is associated with finding the data object in storage. 
     
     
         12 . The system of  claim 1 , wherein the plurality of resources comprises a plurality of storage nodes. 
     
     
         13 . The system of  claim 1 , wherein a consistent hash function is used to compute the resource-specific affinity values. 
     
     
         14 . The system of  claim 1 , wherein the processor is further configured to:
 detect that a removed resource has been removed from the plurality of resources; and   remove a resource-specific affinity value associated with the removed resource from the resource-specific affinity values.   
     
     
         15 . The system of  claim 1 , wherein the processor is further configured to:
 detect that an added resource has been added to the plurality of resources; and   compute a resource-specific affinity value for the added resource with respect to the data object.   
     
     
         16 . A method of selecting a resource, comprising:
 computing, using a processor, for each of a plurality of resources, with respect to the data object, a resource-specific affinity value;   applying a bias to each of at least a subset of the resource-specific affinity values, wherein the bias comprises a function that is monotonically increasing; and   using the resource-specific affinity values to select a resource to fulfill the operation associated with the data object.   
     
     
         17 . The method of  claim 16 , wherein a consistent hash function is used to compute the resource-specific affinity values. 
     
     
         18 . The method of  claim 16 , further comprising:
 detecting that a removed resource has been removed from the plurality of resources; and   removing a resource-specific affinity value associated with the removed resource from the resource-specific affinity values.   
     
     
         19 . The method of  claim 16 , further comprising:
 detecting that an added resource has been added to the plurality of resources; and   computing a resource-specific affinity value for the added resource with respect to the data object.   
     
     
         20 . A computer program product for selecting a resource, the computer program product being embodied in a computer readable storage medium and comprising computer instructions for:
 computing for each of a plurality of resources, with respect to the data object, a resource-specific affinity value;   applying a bias to each of at least a subset of the resource-specific affinity values, wherein the bias comprises a function that is monotonically increasing; and   using the resource-specific affinity values to select a resource to fulfill the operation associated with the data object.