Introducing Latency and Delay in a SAN Environment

Patent metadata

Field	Value
Publication number	US-2017124231-A1
Application number	US-201715406088-A
Country	US
Kind code	A1
Filing date	Jan 13, 2017
Priority date	Apr 7, 2014
Publication date	May 4, 2017
Grant date	—

Abstract

Simulating latency in a network environment. A first device receives a latency request. The first device sends a latency support confirmation. The first device receives an I/O frame. The I/O frame comprising a latency simulating bit and a latency duration. Based on the latency simulating bit and the latency duration, holding, by the first device, the I/O frame. The first device sends the I/O frame on.

First claim

What is claimed is:

1 . A method for simulating latency, said method comprising:
receiving, by a first device, a latency request; sending, by said first device, a latency support confirmation; receiving, by said first device, an I/O frame, said I/O frame comprising a latency simulating bit and a latency duration; based on said latency simulating bit and said latency duration, holding, by said first device, said I/O frame; and sending, by said first device, said I/O frame.

2 . The method according to claim 1 , wherein said holding further comprises calculating, by said first device, a latency period based on said latency duration, said latency period being a period of time that said I/O frame is held for.

3 . The method according to claim 2 , wherein said latency period is calculated by said first device using a statistical distribution.

4 . The method according to claim 3 , wherein said statistical distribution comprises a function selected from a group consisting of:
a constant value; an exponential probability density function, said latency delay representing said exponential probability density function by an expected value of said latency delay representing the 63.2 nd percentile; an uniform probability density function, said latency delay representing said uniform probability density function by a lower limit and an upper limit of said latency delay; a Gaussian probability density function, said latency delay representing said Gaussian probability density function by an arithmetic mean representing the 50 th percentile, a standard deviation of said latency delay, and the number of standard deviations to be included; a binary probability density function, said latency delay representing said binary probability density function by a first latency duration and a second latency duration; a Rayleigh probability density function, said latency delay representing said Rayleigh probability density function by an expected value of said latency delay representing the 63.2 nd percentile and a shape factor of two; and a Weibull probability density function, said latency delay representing said Weibull probability density function by an expected value of said latency duration representing the 63.2 nd percentile, a shape factor, and a latency offset.

5 . The method according to claim 1 , wherein said holding further comprises calculating, by a second device, a latency period based on said latency duration, said latency period being a period of time that said I/O frame is held for, said latency period overwriting data stored in said latency duration field.

6 . The method according to claim 4 , wherein said latency period is calculated by said second device using a statistical distribution.

7 . The method according to claim 6 , wherein said statistical distribution comprises a function selected from a group consisting of:
a constant value; an exponential probability density function, said latency delay representing said exponential probability density function by an expected value of said latency delay representing the 63.2 nd percentile; an uniform probability density function, said latency delay representing said uniform probability density function by a lower limit and an upper limit of said latency delay; a Gaussian probability density function, said latency delay representing said Gaussian probability density function by an arithmetic mean representing the 50 th percentile, a standard deviation of said latency delay, and the number of standard deviations to be included; a binary probability density function, said latency delay representing said binary probability density function by a first latency duration and a second latency duration; a Rayleigh probability density function, said latency delay representing said Rayleigh probability density function by an expected value of said latency delay representing the 63.2 nd percentile and a shape factor of two; and a Weibull probability density function, said latency delay representing said Weibull probability density function by an expected value of said latency duration representing the 63.2 nd percentile, a shape factor, and a latency offset.

8 . The method according to claim 1 , wherein said first device is a server or a switch.

9 . The method according to claim 5 , wherein said second device is a server or a switch.

10 . The method according to claim 1 , wherein said first device is a server comprising a network adapter, said network adapter configured for said holding of said I/O frame.

11 . The method according to claim 1 , said first device comprises a receiver, said receiver comprising a buffer, said buffer configured for said holding of said I/O frame.

12 . The method according to claim 1 , wherein said I/O frame comprises an I/O command.

Assignees

• Astigarraga Tara
• Dickens Louie A
• Starling Michael E
• Winarski Daniel J
• IBM

Inventors

• Astigarraga Tara
• Dickens Louie A
• Starling Michael E
• Winarski Daniel J

Classifications

• H04L67/1097

  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 title

• H04L41/142

  using statistical or mathematical methods · CPC title

• H04L41/145 Primary

  involving simulating, designing, planning or modelling of a network · CPC title

• H04L43/50

  Testing arrangements · CPC title

• G06F17/18

  for evaluating statistical data {, e.g. average values, frequency distributions, probability functions, regression analysis (forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04)} · CPC title