Storage switch traffic bandwidth control

• US 20060098572A1
• Filed: 04/30/2004
• Published: 05/11/2006
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Zhang, Chao, Frey, Robert Tower
• Granted Patent: US 7,773,521 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04L 41/0896 Bandwidth or capacity management, i.e. automatically increasing or decreasing capacities flow or congestion control using dynamic resource allocation, e.g. in-call renegotiation, H04L47/76
• CPC Class Codes: H04L 41/5003 Managing SLA; Interaction between SLA and QoS
• CPC Class Codes: H04L 41/5009 Determining service level performance parameters or violations of service level contracts, e.g. violations of agreed response time or mean time between failures [MTBF]
• CPC Class Codes: H04L 41/5019 Ensuring fulfilment of SLA
• CPC Class Codes: H04L 43/0894 Packet rate
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/20 Traffic policing
• CPC Class Codes: H04L 47/29 using a combination of thresholds

Abstract

A switch including a processor and method for monitoring bandwidth in the storage switch. The switch includes at least one physical port coupling at least one target and at least one initiator via the physical port. The monitoring method may include the steps of determining whether congestion occurs on the physical port and assigning a weight to bandwidth usage between the initiator and the target based on a minimum and maximum bandwidth settings for each target. The switch may further include a step of controlling bandwidth usage by each of said at least two targets based on minimum and maximum bandwidth settings for each of the targets.

Claims

1. A method for use in a system for storing and accessing data, the system including at least one initiator, at least two targets, and at least one switch having a port, the method comprising:

determining whether congestion occurs at the physical port; and

controlling bandwidth usage by each of at least two targets based on minimum and maximum bandwidth settings for each of the targets.

2. The method of claim 1 wherein the step of controlling comprises rejecting additional commands from the initiator to at least one of the two targets.

3. The method of claim 1 wherein the step of controlling comprises monitoring traffic passing from each of the two targets to the port, and recording a data amount when either of the two targets exceeds a maximum bandwidth.

4. The method of claim 3 wherein the step of monitoring comprises incrementing the data amount by an amount of data read during an excess bandwidth period.

5. The method of claim 3 wherein the step of monitoring comprises decrementing the data amount when a command received for a target with a recorded excess data amount is rejected.

6. The method of claim 1 wherein the step of determining comprises monitoring the physical port for congestion and implementing said controlling step when the physical port is congested.

7. The method of claim 1 wherein said step of controlling comprises monitoring bandwidth from each of said two targets to determine whether the bandwidth exceeds an allowable maximum bandwidth for the target.

8. The method of claim 1 wherein said step of controlling comprises assigning a weight to each target when traffic from the target to the port exceeds an allowable maximum bandwidth for the target and rejecting commands to one of said two targets.

9. The method of claim 8 wherein the step of assigning a weight includes recording a bandwidth overage amount in a record associated with the target.

10. The method of claim 9 wherein the step of recording a bandwidth overage includes recording a number of bytes.

11. The method of claim 9 wherein the step of rejecting additional commands includes the step of determining a requested number of bytes from the command, and reducing the recorded bandwidth overage by the requested number of bytes.

12. The method of claim 9 wherein the step of assigning a weight includes marking traffic from the target to the port based on a two rate marker.

13. The method of claim 12 wherein the step of assigning a weight include marking the traffic using a two rate, three color marking system.

14. The method of claim 13 wherein the step of weighting includes recording all red marked traffic as a bandwidth overage.

15. The method of claim 9 wherein the step of weighting includes recording all yellow traffic as a bandwidth overage if a comparison of a normalized value of the maximum bandwidth exceeds a random number.

16. The method of claim 15 wherein the overage recorded is a frame size of the yellow traffic frame.

17. The method of claim 15 wherein commands directed to one of said at least two targets with a greater bandwidth overage are rejected until its overage is less than an overage of the other of said at least two targets.

18. A method for use in a system for storing and accessing data, the system including at least one initiator, at least two targets, and at least one switch having a port, the method comprising:

monitoring traffic bandwidth from each of said at least two targets to the port;

determining which target should have access to port resources based on a minimum and maximum bandwidth setting for each target; and

controlling access to said targets by rejecting additional commands to the target based on the step of determining.

19. The method of claim 18 wherein said step of determining comprises assigning a priority to each target based on a weighting of traffic for each of said at least two targets.

20. The method of claim 19 wherein the step of assigning a weight includes marking the traffic using a two rate, three color marker.

21. The method of claim 20 wherein the step of assigning a weight includes recording all red marked traffic as a bandwidth overage.

22. The method of claim 20 wherein the step of assigning a weight includes recording all yellow traffic as a bandwidth overage if a comparison of a normalized value of the maximum bandwidth exceeds a random number.

23. The method of claim 20 wherein the overage recorded is a frame size.

24. The method of claim 20 wherein commands directed to one of said at least two targets with a greater bandwidth overage are rejected until its overage is less than an overage of the other of said at least two targets.

25. The method of claim 18 wherein each target includes at least one virtual target communicating with at least one respective physical logical unit.

26. The method of claim 25 wherein the step of monitoring includes monitoring traffic from each of said physical logical units through a respective virtual logical unit.

27. The method of claim 26 wherein the step of controlling comprises rejecting commands from the initiator to the virtual target.

28. A method for use in a system for storing and accessing data, the system including at least one initiator, at least two virtual logical units, at least two physical logical units, and at least one switch having a port, the port accessing each physical logical unit through the switch, the method comprising:

monitoring the bandwidth consumed by each of said at least two virtual targets as a result of traffic from the associated physical logical unit;

determining which target should have access to port resources based on a weighting of traffic returning from a virtual target; and

restricting access to said virtual targets by rejecting additional commands to the target based on the weighting of the target.

29. The method of claim 28 wherein the step of determining comprises recording contention counts for each virtual target.

30. The method of claim 29 wherein the step of generating contention counts include marking traffic from the physical target to the virtual target using a two rate, three color marker.

31. The method of claim 30 wherein the step of generating contention counts includes setting one of said two rates to a maximum bandwidth for the virtual target and one of said two rates to a minimum bandwidth for the virtual target.

32. The method of claim 30 wherein a traffic marked yellow is recorded as a contention count if a normalized value of a maximum bandwidth for the virtual target is greater than a random number generated for comparison with the normalized value.

33. The method of claim 32 wherein the number of contention counts recorded is a frame size.

34. The method of claim 30 wherein traffic marked green is recorded as a reduction in contention counts

35. The method of claim 30 wherein said step of rejecting additional commands to the target is based on a comparison of recorded contention counts for each of the virtual targets.

36. The method of claim 30 wherein commands for the virtual target having an excess amount of contention counts is rejected.

37. The method of claim 36 wherein the excess amount of contention counts is the smallest number of contention counts of all virtual targets accessing the port.

38. The method of claim 37 wherein the excess amount is reduced by the requested number of bytes in a command rejected for the virtual target.

39. A storage switch having at least one physical port providing access to at least two targets, comprising:

load balancing circuitry affiliated with the port including a memory storing a record of each target, the record including a minimum and maximum bandwidth allocation for the target; and

processing circuitry affiliated with the port including a bandwidth monitor for each of said at least two targets, the processing circuitry maintaining a weighted record of bandwidth used by each target and rejecting additional commands to at least one target based on the record if the physical port is congested.

40. The switch of claim 39 wherein the processing circuitry includes a contention count generator and a two rate, three color meter and marker.

41. The switch of claim 40 wherein the contention count generator increments a contention count record for one of the two targets responsive to the traffic color marked by two rate three color marker.

42. The switch of claim 40 wherein the contention count is incremented if the color marked is yellow and a normalized value for the maximum bandwidth allocation is greater than a random number with which it is compared.

43. The switch of claim 40 wherein the contention count is decremented if the color marked is yellow and a normalized value for the maximum bandwidth allocation is less than a random number with which it is compared.

44. The switch of claim 40 wherein the contention count is decremented if the color marked is green.

45. The switch of claim 40 wherein the contention count is incremented if the color marked is red.

46. The switch of claim 39 wherein each target includes at least one virtual target communicating with at least one respective physical logical unit.

47. The switch of claim 46 wherein the processing circuitry includes a command rejecter for commands from the initiator to the virtual target responsive to the weighted record.

48. A storage network including:

an initiator;

at least two targets;

a switch including at least one port coupled to the initiator, the switch providing access to the targets, the switch including at least one processor associated with the port having a record including bandwidth allocations for each of said at least two targets, and code operable to instruct the processor to;

monitor bandwidth consumed by each of said at least two targets,

determine which target should have access to port resources based on a weighting of traffic returning from a target to the port, and

control access to said targets by rejecting additional commands to the target based on the weighting of the target.

49. The network of claim 48 wherein said code instructing the processor to monitor of monitoring the bandwidth comprises includes code assigning a weight to each target when traffic from the target to the port exceeds an allowable maximum bandwidth for the target.

50. The network of claim 49 wherein said code instructing the processor to assign a weight a includes code marking traffic from the target to the port based on a two rate marker.

51. The network of claim 50 wherein said code instructing the processor to assign a weight includes code for instructing the processor to mark the traffic using a two rate, three color marking system.

52. The network of claim 50 wherein said code instructing the processor to assign a weight includes code for instructing the processor to record all red marked traffic as a bandwidth overage.

53. The network of claim 50 wherein said code instructing the processor to assign a weight includes code for instructing the processor to mark all yellow traffic as a bandwidth overage if a comparison of a normalized value of the maximum bandwidth exceeds a random number.

54. The network of claim 50 wherein said code instructing the processor to assign a weight includes code for instructing the processor to record the overage recorded as a frame size.

55. The network of claim 50 wherein said code instructing the processor to control access includes code for instructing the processor to reject commands directed to one of said at least two targets with a greater bandwidth overage are rejected until its overage is less than an overage of the other of said at least two targets.

56. A method for monitoring bandwidth in a storage switch, the switching including at least one physical port coupling at least one target and at least one initiator via the physical port, comprising:

determining whether congestion occurs on the physical port;

assigning a weight to bandwidth usage between the initiator and the target based on a minimum and maximum bandwidth settings for each target.

57. The method of claim 56 wherein the step of assigning a weight includes the steps of monitoring bandwidth from the target using a two rate, three color marker.

58. The method of claim 57 wherein the step of assigning a weight includes recording all red marked traffic as a bandwidth overage.

59. The method of claim 57 wherein the step of assigning a weight includes recording all yellow traffic as a bandwidth overage if a comparison of a normalized value of the maximum bandwidth exceeds a random number.

60. The method of claim 59 wherein the overage recorded is a frame size.

61. The method of claim 59 wherein commands directed to one of said at least two targets with a greater bandwidth overage are rejected until its overage is less than an overage of the other of said at least two targets.

62. The method of claim 56 wherein the step of assigning a weight includes determining a smallest overage amount of all targets and adding the smallest overage amount as an excess amount.

63. The method of claim 56 wherein the bandwidth usage is the result of a read command.

64. The method of claim 56 wherein the bandwidth usage is the result of a write command.