Load balancing using directory services in a data processing system

• US 6,438,595 B1
• Filed: 06/24/1998
• Issued: 08/20/2002
• Est. Priority Date: 06/24/1998
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Blumenau, Steven M., Raz, Yoav
• Primary Examiner(s): Harrell, Robert B.
• Assistant Examiner(s): Jaroenchonwanit, Bunjob
• Application Number:
  US09/104,597
• Time in Patent Office: 1,518 Days
• Field of Search: 709/231, 709/229, 709/226, 709/219, 709/205, 709/104, 709/238, 714/4, 714/769, 714/770, 711/111, 711/113, 711/114, 711/150, 710/73, 370/352
• US Class Current: 709/226
• CPC Class Codes: G06F 9/5083 Techniques for rebalancing the load in a distributed system
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/35 involving non-standard use of addresses for implementing network functionalities, e.g. coding subscription information within the address or functional addressing, i.e. assigning an address to a function
• CPC Class Codes: H04L 61/45 Network directories; Name-to-address mapping
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1006 with static server selection, e.g. the same server being selected for a specific client
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/1036 Load balancing of requests to servers for services different from user content provisioning, e.g. load balancing across domain name servers
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

A data network links a number of host processors to alternative shared resources. In order to allocate a respective subset of the alternative shared resources to each host, a directory service of the network is programmed to present a respective view of the network to each host. For example, hosts on the same network loop may see a different picture of the network. When a host logs into the network, the directory service reports to the host information about the alternative shared resources that the host should use. The host then commences a sequence of data processing operations during which the host accesses only the shared resources that were reported to it by the directory service. The shared resources, for example, are ports of a storage subsystem, and a respective subset of the ports is assigned to each host to balance loading of the hosts on the ports.

Claims

1. In a data processing system having a plurality of host processors and a data network linking the host processors to alternative shared resources for the communication of service requests from the host processors to the alternative shared resources, a method of controlling access of the host processors to the alternative shared resources, said method comprising:

a) storing in a directory a specification of a respective subset of the alternative shared resources which are accessible to each of the host processors, and operating a directory service for reporting network addresses of the alternative shared resources, the directory service accessing the directory in response to a request from each host processor for reporting to said each host processor a set of network addresses of the alternative shared resources for said each host processor, said set of network addresses of the alternative shared resources for said each host processor including only the network addresses of the alternative shared resources in the respective subset of the alternative shared resources which are accessible to said each host processor; and

b) operating said each host processor including;

(i) said each host processor sending a request to the directory service for a report of network addresses of the alternative shared resources, and receiving from the directory service a report of the set of network addresses of the alternative shared resources for said each host processor; and

then

(ii) said each host processor commencing a sequence of data processing operations during which said each host processor transmits service requests to at least one network address in the set of network addresses of the alternative shared resources for said each host processor;

which includes estimating respective loadings that the host processors will have on the alternative shared resources, and selecting the respective subsets based on the estimates of the respective loadings in order to balance loadings of the host processors on the alternative shared resources, and

which includes measuring loadings of the host processors on the alternative shared resources in order to estimate respective loadings that the host processors will have on the alternative shared resources;

wherein the loadings are measured by computing a modulus from a network address intercepted from the data network, and indexing a table with the modulus to locate an accumulator for accumulating an occurrence of the network address intercepted from the data network.

2. In a data processing system having a plurality of host processors and a data network including a switch linking the host processors to a plurality of ports of a storage subsystem for transmission of storage access requests from the host processors to the ports of the storage subsystem, a method of controlling access of the host processors to the ports of the storage subsystem, said method comprising:

a) storing in a directory a specification of a respective subset of the ports of the storage subsystem which are accessible to each of the host processors, and operating a directory service for accessing the directory and for reporting to each host processor the respective subset of the ports of the storage subsystem which are accessible to said each host processor; and

b) operating said each host processor including;

(i) said each host processor sending a request to the directory service for a report of the respective subset of ports of the storage subsystem which are accessible to said each host processor; and

receiving from the directory service a report of the subset of the ports of the storage subsystem which are accessible to said each host processor; and

then

(ii) said each host processor commencing a sequence of data processing operations during which said each host processor transmits storage access requests to at least one port included in the respective subset of ports of the storage subsystem which are accessible to said each host processor.

3. The method as claimed in claim 2, wherein the directory service is a name server for providing information about ports linked to the switch for transmission and reception of data routed through the switch, and the directory service reports to said each host processor a respective network address for each port included in the respective subset of ports of the storage subsystem which are accessible to said each host processor.

4. The method as claimed in claim 3, which includes estimating respective loadings that the host processors will have on the ports of the storage subsystem, and selecting the respective subsets based on the estimates of the respective loadings in order to balance loadings of the host processors on the ports of the storage subsystem.

5. The method as claimed in claim 4, which includes measuring loadings of the host processors on the ports of the storage subsystem in order to estimate respective loadings that the host processors will have on the ports of the storage subsystem.

6. The method as claimed in claim 5, wherein the loadings are measured by computing a modulus from a network address intercepted from the data network, and indexing a table with the modulus to locate an accumulator for accumulating an occurrence of the network address intercepted from the data network.

7. The method as claimed in claim 4, wherein the respective subsets are further selected based on respective priorities assigned to the host processors by including different numbers of the ports of the storage subsystem in the respective subsets.

8. The method as claimed in claim 2, wherein said each host processor sends the request to the directory service after said each host processor logs into the data network and is assigned a network address.

9. The method as claimed in claim 2, wherein the respective subset of ports of the storage subsystem which are accessible to at least one of the host processors includes a plurality of ports of the storage subsystem, and said at least one of the host processors sends storage access requests in round-robin fashion to the plurality of ports in the respective subset of ports of the storage subsystem which are accessible to said at least one of the host processors.

10. The method as claimed in claim 2, wherein the data processing system includes a directory service for reporting network addresses of all of the storage subsystem ports, and the method further includes incorporating into the data network a substitute directory service to which said each host processor sends the request for a report of ports of the storage subsystem that said each host processor should access.

11. The method as claimed in claim 10, wherein the data processing system further includes at least one host processor that does not send any requests to the substitute directory service, and the method further includes said at least one host processor sending a request to the directory service for reporting all of the ports of the storage subsystem, and in response said at least one processor obtaining a report of all of the ports of the storage subsystem, and thereafter said at least one host processor sending storage access requests to ports of the storage subsystem.

12. The method as claimed in claim 2, wherein at least some of the host processors have more than one possible path through the network to at least some of the ports of the storage subsystem, and the method further includes the directory service reporting to each of said at least some of the host processors a respective subset of the possible paths through the network to said at least some of the ports of the storage subsystem.

13. A digital computer programmed to provide a directory service in a data network, the digital computer being programmed with a configuration database of information about host processors in the network and shared resources in the network that are accessible to the host processors, the configuration database further including information specifying, for each host processor, a respective subset of the shared resources which are accessible to said each host processor, the digital computer being programmed to respond to a request from said each host processor for information about resources in the network by reporting to said each host processor information about the respective subset of the shared resources that are accessible to said each host processor, thereby selectively restricting access of the host processors to the shared resources;

wherein the digital computer is programmed to collect information about loading of the host processors upon the shared resources, and to adjust the respective subset of the shared resources which are accessible to said each host processor based upon the loading of the host processors upon the shared resources in order to balance loading of the host processors upon the shared resources.

14. The digital computer as claimed in claim 13, wherein the digital computer is programmed to collect information about loadings of the host processors upon the shared resources by computing a modulus from a network address intercepted from the data network, and indexing a table with the modulus to locate an accumulator for accumulating an occurrence of the network address intercepted from the data network.

15. A machine readable program storage device containing a program for programming a digital computer to provide a directory service in a data network, the directory service accessing a configuration database of information about host processors in the network and shared resources in the network and information specifying for each host processor a respective subset of the shared resources which are accessible to said each host processor, the directory service responding to a request from said each host processor for information about resources in the network by reporting to said each host processor information about the subset of the shared resources that are accessible to said each host processor, thereby selectively restricting access of the host processors to the shared resources;

wherein the computer program is executable by the digital computer for collecting information about loading of the host processors upon the shared resources, and adjusting the respective subset of the shared resources which are accessible to said each host processor based upon the loading of the host processors upon the shared resources in order to balance loading of the host processors upon the shared resources.

16. The machine readable program storage device as claimed in claim 15, wherein the computer program is executable by the digital computer for collecting information about loadings of the host processors upon the shared resources by computing a modulus from a network address intercepted from the data network, and indexing a table with the modulus to locate an accumulator for accumulating an occurrence of the network address intercepted from the data network.

17. A storage network comprising, in combination:

a cached storage subsystem including a plurality of storage devices, a cache memory linked to the storage devices for filling the cache with data from the storage devices, and a plurality of port adapters providing storage ports for access to the cache memory; and

a switch having a plurality of network ports and being linked to the storage ports for selectively routing data access requests from the network ports to the storage ports, the network ports being connectable for receiving the data access requests from a plurality of host processors;

wherein the storage network includes a digital computer programmed with a configuration database of information about the host processors and the storage ports, the configuration database further including information specifying, for each host processor, a respective subset of the storage ports which are accessible to said each host processor, the digital computer being programmed to respond to a request from said each host processor for information about the storage ports by reporting to said each host processor information about the respective subset of the storage ports which are accessible to said each host processor, and thereby selectively restrict access of the host processors to the storage ports.

18. The storage network as claimed in claim 17, which further includes a network loop connected to each of the network ports for linking a respective group of the host computers to said each of the network ports for transmission of storage access requests from the host computers in the respective group to said each of the network ports.

19. The storage network as claimed in claim 17, wherein the digital computer is further programmed to assign temporary addresses to the storage ports and to the hosts linked to the network ports.

20. The storage network as claimed in claim 17, wherein the digital computer is programmed to respond to a network login request from said each host processor by returning a temporary address assigned to said each host processor.

21. The storage network as claimed in claim 17, wherein the digital computer is programmed to be a substitute for a network directory.

22. The storage network as claimed in claim 21, wherein the digital computer is programmed to access the network directory to obtain network addresses of the storage ports in the respective subset of storage ports that are accessible to said each host processor, and to forward the network addresses to said each host processor.

23. The storage network as claimed in claim 17, wherein the digital computer is a control computer of said switch.

24. The storage network as claimed in claim 17, wherein the digital computer is programmed to collect information about loading of the host processors upon the storage ports, and to adjust the respective subset of the storage ports which are accessible to said each host processor based upon the loading of the host processors upon the storage ports in order to balance loading of the host processors upon the storage ports.

25. The storage network as claimed in claim 24, wherein the digital computer is programmed to collect information about loadings of the host processors upon the storage ports by computing a modulus from a network address intercepted from a transmission between the host processors and the storage ports, and indexing a table with the modulus to locate an accumulator for accumulating an occurrence of the network address intercepted from the transmission between the host processors and the storage ports.

26. A digital computer programmed to provide a directory service in a data network, the digital computer being programmed with a configuration database of information about host processors in the network and shared resources in the network that are accessible to the host processors, the configuration database further including information specifying, for each host processor, a respective subset of the shared resources which are accessible to said each host processor, the digital computer being programmed to respond to a request from said each host processor for information about resources in the network by reporting to said each host processor information about the respective subset of the shared resources that are accessible to said each host processor, thereby selectively restricting access of the host processors to the shared resources;

wherein the digital computer is programmed to be a substitute for a network directory;

the digital computer is programmed to access the network directory to obtain network addresses of resources in the respective subset of resources that are accessible to said each host processor, and to forward the network addresses to said each host processor; and

the digital computer is programmed to collect information about loading of the host processors upon the shared resources, and to adjust the respective subset of the shared resources which are accessible to said each host processor based upon the loading of the host processors upon the shared resources in order to balance loading of the host processors upon the shared resources.

27. The digital computer as claimed in claim 26, wherein the digital computer is programmed to collect information about loadings of the host processors upon the shared resources by computing a modulus from a network address intercepted from the data network, and indexing a table with the modulus to locate an accumulator for accumulating an occurrence of the network address intercepted from the data network.

28. A digital computer programmed to provide a directory service in a data network, the digital computer being programmed with a configuration database of information about host processors in the network and shared resources in the network that are accessible to the host processors, the configuration database further including information specifying, for each host processor, a respective subset of the shared resources which are accessible to said each host processor, the digital computer being programmed to respond to a request from said each host processor for information about resources in the network by reporting to said each host processor information about the respective subset of the shared resources that are accessible to said each host processor, thereby selectively restricting access of the host processors to the shared resources;

wherein the digital computer is further programmed to assign temporary addresses to ports in the network;

the digital computer is programmed to respond to a network login request from said each host processor by returning a temporary address assigned to said each host processor;

the digital computer is a switch control computer of a switch for the network; and

the digital computer is programmed to collect information about loading of the host processors upon the shared resources, and to adjust the respective subset of the shared resources which are accessible to said each host processor based upon the loading of the host processors upon the shared resources in order to balance loading of the host processors upon the shared resources.

29. The digital computer as claimed in claim 28, wherein the digital computer is programmed to collect information about loadings of the host processors upon the shared resources by computing a modulus from a network address intercepted from the data network, and indexing a table with the modulus to locate an accumulator for accumulating an occurrence of the network address intercepted from the data network.

30. In a data processing system having a plurality of host processors and a data network including a switch linking the host processors to a plurality of ports of a storage subsystem for transmission of storage access requests from the host processors to the ports of the storage subsystem, each of the ports being accessible to each of the host processors through the switch, a method of balancing loading of the host processors upon the ports of the storage subsystem, said method comprising:

a) storing in a directory lists of the ports of the storage subsystem, the lists of ports including a respective list of the ports of the storage subsystem which each of the host processor should access, and operating a directory service for accessing the directory and for reporting to said each host processor the respective ports of the storage subsystem which said each host processor should access; and

b) operating said each host processor including;

(i) said each host processor sending a request to the directory service for a report of the respective ports of the storage subsystem which said each host processor should access, and receiving from the directory service a report of the respective ports of the storage subsystem which said each host processor should access; and

then

(ii) said each host processor commencing a sequence of data processing operations during which said each host processor transmits storage access requests to at least one of the ports of the storage subsystem which said each host processor should access;

wherein the method further includes monitoring loadings of the host processors upon the storage subsystem by obtaining for each of the host processors a respective count of frames of data transmitted between said each host processor and the ports of the storage subsystem, and adjusting the respective list of storage subsystem ports which said each host processor should access based on the respective count of frames of data transmitted between said each host processor and the ports of the storage subsystem.

31. The method as claimed in claim 30, which further includes monitoring the loading upon each of the storage subsystem ports by obtaining for each of the storage subsystem ports a respective count of frames of data transmitted between said each of the storage subsystem ports and the host processors, and responding to a log in of one of the host processors by including, in the respective list of storage subsystem ports that said one of the host processors should access, a number of the storage subsystem ports having the least respective counts of frames of data transmitted between said each of the storage subsystem ports and the host processors.

32. A storage system for providing data storage to a plurality of host processors, the storage system including a storage subsystem and a data network including a switch linking the host processors to a plurality of ports of a storage subsystem for transmission of storage access requests from the host processors to the ports of the storage subsystem, each of the ports being accessible to each of the host processors through the switch, the storage system further including a directory service accessible to the hosts for balancing loading of the host processors upon the ports of the storage subsystem, wherein the directory service contains lists of the ports of the storage subsystem, the lists of ports including a respective list of the ports of the storage subsystem which each of the host processor should access, the directory service being responsive to the host processors for reporting to said each host processor the respective ports of the storage subsystem which said each host processor should access, and the directory service being responsive to loadings of the host processors upon the storage subsystem by obtaining for each of the host processors a respective count of frames of data transmitted between said each host processor and the ports of the storage subsystem, and adjusting the respective list of storage subsystem ports which said each host processor should access based on the respective count of frames of data transmitted between said each host processor and the ports of the storage subsystem.

33. The storage system as claimed in claim 32, wherein the directory service is further programmed for monitoring the loading upon each of the storage subsystem ports by obtaining for each of the storage subsystem ports a respective count of frames of data transmitted between said each of the storage subsystem ports and the host processors, and responding to a log in of one of the host processors by including, in the respective list of storage subsystem ports that said one of the host processors should access, a number of the storage subsystem ports having the least respective counts of frames of data transmitted between said each of the storage subsystem ports and the host processors.