Volume location service for a distributed file system
View Patent ↗Software implementing a volume location service on a computer is responsible for instructing clients where they can find volumes on a distributed file system storing instances of desired resources. A user queries the volume location service software for the location of instances of a desired resource. The user can also specify attributes (e.g., read-only access) to reduce the number of returned hosts. The volume location service software accesses a back-end database for the hosts with the optional attribute storing resource instances. The back-end database stores information about what hosts store instances of what resources. The back-end database is pluggable, and can be changed as desired by the administrator of the volume location service. The volume location service software then returns to the user the found hosts.
1. An apparatus providing a location service for locating at least one instantiation of a resource on a computer network, the apparatus comprising:
an interface for communicating with the location service;
a pluggable back-end database for storing locations of the instantiations of the resource selected from a plurality of pluggable back-end databases, each of the plurality of pluggable back-end databases capable of processing a request for a location of an instance of a resource via the interface;
means for querying the pluggable back-end database for at least one host storing the instantiation of the resource and specifying a filter for the pluggable back-end database; and
means for returning a record in the pluggable back-end database through the interface, the record including the host storing the resource instantiation that satisfies the filter and an attribute associated with the resource instantiation.
2. An apparatus according to claim 1 , wherein the pluggable back-end database includes attributes of each resource instantiation.
3. An apparatus according to claim 1 , the location service further comprising a synchronization module for synchronizing the plurality of pluggable back-end databases.
4. An apparatus according to claim 1 , wherein the plurality of pluggable back-end databases includes at least two different back-end database implementations.
5. An apparatus according to claim 1 , wherein the back-end database includes functions for accessing the back-end database through the interface.
6. An apparatus according to claim 1 , wherein the interface includes an asynchronous messaging system for communicating with the location service.
7. A location service method for locating at least one instantiation of a resource, the method comprising:
selecting a back-end database from a plurality of back-end databases, each of the plurality of back-end databases capable of responding to a query for a location of an instance of the resource;
coupling the back-end database to an interface;
receiving a request for the location of the resource at the interface, including receiving a filter for the first resource instantiation;
querying the back-end database for at least a first host storing a first resource instantiation that satisfies the filter; and
returning at least one location of the first host storing the first resource instantiation.
8. A location service method according to claim 7 , the method further comprising returning an attribute associated with the first resource instantiation on the first host.
9. A computer readable medium containing a program implementing a location service method to locate at least one instantiation of a resource, the program comprising:
selection software to select a back-end database from a plurality of back-end databases, each of the plurality of back-end databases capable of responding to a query for a location of an instance of the resource;
coupling software to couple the back-end database to an interface;
reception software to receive a request for location of the resource at the interface, including attribute reception software to receive a filter for the first resource instantiation;
query software to query the back-end database for a first host storing a first resource instantiation that satisfies the filter; and
return software to return at least a location of the first host storing the first resource instantiation from the location service.
10. A computer-readable medium containing a program according to claim 9 , the program further comprising second return software to return an attribute associated with the first resource instantiation on the first host.
11. A system for using a location service to locate a resource, the system comprising:
a network including at least two computers;
a distributed filed system distributed across the network;
a resource accessible via the network;
software implementing the location service stored on at least one of the computers, the location service software including a pluggable back-end database, the pluggable back-end database selected from a plurality of pluggable back-end databases, each of the pluggable back-end databases storing locations of instances of the resource; and
query means for querying the location service software for the location of instances of the resource that stratifies a filter.
12. A system according to claim 11 , wherein:
the apparatus further comprises a description of an attribute for controlling the use of the location service software; and
the query means including using means to use the attribute description for controlling the use of the location service software.
13. A system according to claim 11 , wherein a subset of the network is defied by a management context.
14. A system according to claim 13 , wherein the management context includes means for locating the location service.
15. A system according to claim 11 , further comprising utilization means for utilizing a resource instance returned from the location service software in response to the query.