Method and system to simulate delays in geographically distributed computing environments

• US 20060193263A1
• Filed: 02/25/2005
• Published: 08/31/2006
• Est. Priority Date: 02/25/2005
• Status: Abandoned Application

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Vanamamalai, Thothathri, Mehra, Karan
• Application Number:
  US11/066,077
• Publication Number:
  US 20060193263A1
• Time in Patent Office: Days
• US Class Current: 370/241
• CPC Class Codes: H04L 12/16 Arrangements for providing special services to substations
• CPC Class Codes: H04L 43/0858 One way delays
• CPC Class Codes: H04L 43/10 Active monitoring, e.g. heartbeat, ping or trace-route

Abstract

Systems and methods are described for implementing a delay driver within a cluster service storage stack, which delay driver simulates the latency experienced between two nodes in geographically distant locations. The delay driver determines whether I/O request packets should be delayed, selects the number and types of I/O requests packets to be delayed and the amount of time to delay processing of the packets. Through the use of such a driver, a user is able to simulate various conditions that geoclusters may experience when separated over large distances.

Claims

1. A method for simulating propagation delay, the method comprising the steps of:

intercepting input/output request packets (IRPs) intended for processing within a queue;

delaying processing of predetermined IRPs for a predetermined period of time; and

requeuing the predetermined IRPs for processing after the predetermined period of time has elapsed.

2. The method of claim 1, wherein the predetermined period of time represents the delay associated with propagating a signal through a physical cable.

3. The method of claim 1, wherein queue processes IRPs transmitted from a geocluster and destined for a storage device.

4. The method of claim 3, wherein the storage device is a logical device.

5. The method of claim 3, wherein the storage device is a physical device.

6. The method of claim 1, wherein the predetermined IRPs are comprised of a set of IRPs of a single type.

7. The method of claim 1, wherein the predetermined IRPs are comprised of a set of every Nth packet sent to the queue.

8. The method of claim 7, wherein every Nth packet is every 3rd packet.

9. A method of processing data packets, the method comprising the steps of:

estimating the propagation time associated with transmitting an input/output request packet (IRP) from a geocluster to a physically distant storage device;

establishing a queue for processing IRPs, wherein the queue operates in a plurality of modes;

delaying predetermined IRPs for a delay period in a first mode of queue operation; and

processing the predetermined IRPs without a delay in a second mode of queue operation.

10. The method of claim 9, wherein the delayed IRPs are processed according to the second mode of operation at the conclusion of the delay period.

11. The method of claim 9, wherein the delay period represents the propagation time.

12. The method of claim 9, further comprising the step of setting a flag to determine the mode of queue operation.

13. The method of claim 9, further comprising the step of marking each delayed IRP as pending during the delay period.

14. The method of claim 9, wherein the step of delaying predetermined IRPs is accomplished through the use of a timer.

15. The method of claim 9, wherein the storage device is a logical device.

16. The method of claim 9, wherein a first Input/Output Control (“

IOCTL”

) enables the queue'"'"'s first mode of operation, a second IOCTL sets the delay period, and a third IOCTL disables the queue'"'"'s first mode of operation.

17. A computer-readable medium having computer-executable instructions for performing steps for processing data packets, comprising:

selectively intercepting input/output request packets (IRPs) intended for processing within a queue;

delaying processing of selected IRPs for a predetermined period of time; and

processing the selected IRPs after the predetermined period of time has elapsed.

18. The computer-readable medium as in claim 17, wherein the predetermined period of time represents the delay associated with propagating a signal through a physical cable.

19. The computer-readable medium as in claim 17, wherein the queue processes IRPs transmitted from a geocluster and destined for a storage device.

20. The computer-readable medium as in claim 17, wherein no IRPs are selectively intercepted.