Reliability evaluation system, reliability evaluating method, and reliability evaluation program for information system

• US 7,730,363 B2
• Filed: 09/30/2005
• Issued: 06/01/2010
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Toshiba Solutions Corporation (Toshiba Corporation)
• Original Assignee: Toshiba Solutions Corporation (Toshiba Corporation)
• Inventors: Okuda, Hiroaki, Takezawa, Nobuhisa, Uenohara, Yuuji, Nakahara, Katsuhiko, Takayama, Masayuki
• Primary Examiner(s): Beausoliel; Robert
• Assistant Examiner(s): Manoskey; Joseph D
• Application Number:
  US11/576,395
• Publication Number:
  US 20080059840A1
• Time in Patent Office: 1,705 Days
• Field of Search: 714/4, 714/21, 714/26, 714/30, 714/33, 714/37, 714/39, 714/40, 714/43, 714/47, 705/400
• US Class Current: 714/47.1
• CPC Class Codes: G05B 23/0248 Causal models, e.g. fault tree; digraphs; qualitative physics
• CPC Class Codes: G06F 11/008 Reliability or availability analysis
• CPC Class Codes: G06Q 30/0283 Price estimation or determination

Abstract

A system includes an input unit (2) to which failure information corresponding to failure modes of constituents indicating software and hardware, a system configuration information and a standard value of system availability are inputted, a producing unit (32) producing a fault tree based on the system configuration information, a calculating unit (34) calculating unavailability corresponding to the failure modes based on a result of analyzing the failure information, and calculating system availability based on the calculated unavailability and the fault tree, a determining unit (35) determining whether the system availability meets the standard value, an extracting unit (36) extracting a basic event related to an increase in the system availability when the system availability is determined to be below the standard value, and resetting units (38, 39) resetting new unavailability and the like based on whether it is possible to reduce the unavailability of the extracted basic event.

Claims

1. A reliability evaluation system for an information system, comprising:

an information inputting unit configured to input information necessary for reliability evaluation of the information system provided with an instrument, containing at least information concerning constituents indicating both software for executing a function of the instrument and hardware constituting the instrument, or concerning failures corresponding to failure modes of a constituent group formed of the constituents, system configuration information indicating information concerning a configuration of the information system employing the instrument and any of the constituents and the constituent group, and a standard value of system availability indicating availability of the entire information system;

an information analyzing unit having a processor programmed to analyze information on the failures of each of the failure modes of any of the constituents and the constituent group, and thereby obtaining analysis information thereon;

a fault-tree producing unit configured to produce a fault tree indicating hierarchical logical relationships from a top event indicating a failure mode of the information system to basic events indicating the failure modes of any of the constituents and the constituent group on the basis of the system configuration information;

an unavailability calculating unit configured to calculate unavailability of any of the constituents and the constituent group corresponding to the failure modes of any of the constituents and the constituent group on the basis of the analysis information

a system availability calculating unit configured to calculate, on the basis of the fault tree and the unavailability corresponding to the basic events, availability corresponding to the top event as system availability in a case where it is supposed that the calculated unavailability is unavailability corresponding to the basic events equivalent to the failure modes of any of the constituents and the constituent group;

an availability determining unit configured to determine whether or not the calculated system availability meets the standard value of the system availability;

a basic-event extracting unit configured to extract the basic event related to an increase in the system availability by use of a relationship between variation in the unavailability corresponding to the basic events and variation in the unavailability corresponding to the top event, in a case where it is determined that the calculated system availability does not meet the standard value; and

a first resetting unit configured to reset new analysis information corresponding to the extracted basic event in a case where it is possible to reduce the unavailability corresponding to the extracted basic event, and to reset new system configuration information and information concerning a failure corresponding to a new failure mode in a case where it is not possible to reduce the unavailability corresponding to the extracted basic event.

2. The reliability evaluation system for an information system according to claim 1, wherein the information analyzing unit classifies the information concerning the failures corresponding to the failure modes, out of the information inputted by the information inputting unit, by failure mode and by instrument group, and thereby executes the analysis on the basis of a result of classification, the instrument group indicating a set of instruments which are included in the information system, and which are classified by processing function.

3. The reliability evaluation system for an information system according to any one of claims 1 and 2, wherein

the information concerning the failures, which is inputted to the information inputting unit, includes times to failure of the failure modes of any of the constituents and the constituent group, and

the information analyzing unit calculates failure probabilities of the failure modes of any of the constituents and the constituent group on the basis of the times to failure of the failure modes of any of the constituents and the constituent group, and on the basis of Weibull distribution indicating distribution of the failure probabilities changed according to the times to failure, and thereby obtains the calculated failure probabilities as the analysis information.

4. The reliability evaluation system for an information system according to claim 1, wherein

the information concerning the failures, which is inputted to the information inputting unit, includes times to failure of the failure modes of any of the constituents and the constituent group and failure probabilities corresponding to the times to failure, and

the information analyzing unit calculates distribution of the failure probabilities changed according to the times to failure as the analysis on the basis of the times to failure of the failure modes of any of the constituents and the constituent group and on the basis of the failure probabilities corresponding to the times to failure, then calculates failure probabilities of the failure modes of any of the constituents and the constituent group on the basis of the distribution, and thereby obtains the calculated failure probabilities as the analysis information.

5. The reliability evaluation system for an information system according to any one of claims 1 and 2, wherein

the information concerning the failures, which is inputted to the information inputting unit, includes time to repair for the failure modes of any of the constituents and the constituent group, and

the information analyzing unit calculates a mean time to repair for the failure modes of any of the constituents and the constituent group on the basis of the time to repair for the failure modes of any of the constituents and the constituent group, which is inputted to the information inputting unit, and thereby obtains the calculated mean time to repair as the analysis information.

6. The reliability evaluation system for an information system according to claim 1, wherein

equipment expenses indicating costs necessary for any of the constituents and the constituent group and a cost tolerance value indicating an allowable range of the costs necessary for the information system are inputted to the information inputting unit, and

the reliability evaluation system further comprising:

a cost calculating unit configured to calculate a total sum of the equipment expenses for any of the constituents and the constituent group included in the information system as a cost expense in a case where the availability determining unit determines that the calculated system availability meets the standard value;

a cost determining unit configured to determine whether or not the calculated cost expense exceeds the cost tolerance value; and

a second resetting unit configured to reset, in the information inputting unit, at least one piece of information among a new cost tolerance value, new system configuration information, and new information concerning a failure corresponding to a new failure mode in a case where the calculated cost expense is determined as exceeding the cost tolerance value.

7. The reliability evaluation system for an information system according to claim 6, wherein

an operational loss indicating an operational loss incurred by shutdown of the information system for a unit period and an operating period of the information system are inputted to the information inputting unit,

the cost calculating unit calculates an expected operational-loss value on the basis of the calculated system availability, the operational loss and the operating period, and adds the expected calculated operational-loss value to the total sum of the equipment expenses to calculate the cost expense, and

the second resetting unit resets, in the information inputting unit, at least one piece of information among the new cost tolerance value, a new system availability standard value, the new system configuration information and the new information concerning the failure corresponding to the new failure mode in a case where the calculated cost expense is determined as exceeding the cost tolerance value.

8. A reliability evaluating method for an information system, comprising:

executing information input to input information, as information necessary for reliability evaluation of the information system provided with an instrument, which information contains at least information concerning constituents indicating both software for executing a function of an instrument and hardware constituting the instrument or concerning failures corresponding to failure modes of a constituent group formed of the constituents, system configuration information indicating information concerning a configuration of the information system employing the instrument and any of the constituents and the constituent group, and a standard value of system availability indicating availability of the entire information system;

analyzing information on the failures of each of the failure modes of any of the constituents and the constituent group, and thereby obtaining analysis information thereon;

executing fault-tree production to produce a fault tree indicating hierarchical logical relations from a top event indicating a failure mode of the information system to basic events indicating the failure modes of any of the constituents and the constituent group on the basis of the system configuration information;

executing unavailability calculation to calculate unavailability of any of the constituents and the constituent group corresponding to the failure modes of any of the constituents and the constituent group on the basis of the analysis information;

executing system availability calculation to calculate, on the basis of the unavailability corresponding to the basic events and of the fault tree, availability corresponding to the top event as system availability in a case where it is supposed that the calculated unavailability is unavailability corresponding to the basic events equivalent to the failure modes of any of the constituents and the constituent group;

executing availability determination to determine whether or not the calculated system availability meets the standard value of the system availability;

executing basic event extraction to extract the basic event related to an increase in the system availability by use of a relationship between variation in the unavailability corresponding to the basic events and variation in the unavailability corresponding to the top event, in a case where it is determined that the calculated system availability does not meet the standard value;

executing first resetting to reset new analysis information corresponding to the extracted basic event in a case where it is possible to reduce the unavailability corresponding to the extracted basic event, and to reset new system configuration information and information concerning a failure corresponding to a new failure mode in a case where it is not possible to reduce the unavailability corresponding to the extracted basic event; and

executing the unavailability calculating process and the processes thereafter in a case where the new analysis information corresponding to the extracted basic event is reset, and executing the information analyzing process and the processes thereafter in a case where the information concerning a new failure of the failure mode corresponding to the extracted basic event is reset, and where the new system configuration information and the information concerning the failure corresponding to the new failure mode are reset.

9. The reliability evaluating method for an information system according to claim 8, wherein, in the information analysis, the information concerning the failures corresponding to the failure modes, out of the information inputted by the information inputting unit, is classified by failure mode and by instrument group, and thereby the analysis is executed on the basis of a result of classification, the instrument group indicating a set of instruments which are included in the information system, and which are classified by processing function.

10. The reliability evaluating method for an information system according to any one of claims 8 and 9, wherein

the information concerning the failures, which is inputted by the information input, comprises times to failure of the failure modes of any of the constituents and the constituent group, and

in the information analysis, failure probabilities of the failure modes of any of the constituents and the constituent group are calculated as the analysis on the basis of the times to failure of the failure modes of any of the constituents and the constituent group and on the basis of Weibull distribution indicating distribution of the failure probabilities changed according to the times to failure, and the calculated failure probabilities are obtained as the analysis information.

11. The reliability evaluating method for an information system according to claim 8, wherein

the information concerning the failures, which is inputted by the information input, comprises times to failure in the failure modes of any of the constituents and the constituent group and failure probabilities corresponding to the times to failure, and

in the information analysis, distribution of the failure probabilities changed according to the times to failure is calculated as the analysis on the basis of the times to failure of the failure modes of any of the constituents and the constituent group and on the basis of the failure probabilities corresponding to the times to failure, and failure probabilities of the failure modes of any of the constituents and the constituent group are calculated on the basis of the distribution, and thereby the calculated failure probabilities are obtained as the analysis information.

12. The reliability evaluating method for an information system according to any one of claims 8 and 9, wherein

the information concerning the failures, which is inputted by the information input. includes times to repair for the failure modes of any of the constituents and the constituent group, and

in the information analysis, a mean time to repair for the failure modes of any of the constituents and the constituent group is calculated as the analysis on the basis of the time to repair for the failure modes of any of the constituents and the constituent group inputted to the information inputting unit, and thereby the calculated mean time to repair is obtained as the analysis information.

13. The reliability evaluating method for an information system according to claim 8, wherein,

at the time of the information input, equipment expenses indicating costs necessary for any of the constituents and the constituent group and a cost tolerance value indicating an allowable range of the costs necessary for the information system are inputted, and

the reliability evaluating method further comprising:

executing cost calculation to calculate a total sum of the equipment expenses for any of the constituents and the constituent group included in the information system as a cost expense in a case where the calculated system availability is determined as meeting the standard value,

executing cost determination to determine whether or not the calculated cost expense exceeds the cost tolerance value,

executing second resetting to reset at least one piece of information among a new cost tolerance value, new system configuration information, and new information concerning a failure corresponding to a new failure mode is executed in a case where the calculated cost expense is determined as exceeding the cost tolerance value, and

executing the cost calculation process and the processes thereafter in a case where the new cost tolerance value is reset, and executing the information analyzing process and the processes thereafter in a case where the new system configuration information and the information concerning the failure corresponding to the new failure mode are reset.

14. The reliability evaluating method for an information system according to claim 13, wherein,

at the time of the information input, an operational loss indicating an operational loss incurred by shutdown of the information system for a unit period and an operating period of the information system are inputted,

in the cost calculation, an expected operational-loss value is calculated on the basis of the calculated system availability, the operational loss, and the operating period, a sum of the calculated expected operational-loss value and the total sum of the equipment expanses is calculated as the cost expense,

in the second resetting, at least one piece of information among the new cost tolerance value, a new system availability standard value, the new system configuration information. and the new information concerning the failure corresponding to the new failure mode is reset in a case where the calculated cost expense is determined as exceeding the cost tolerance value, and

the availability determining process and the processes thereafter are executed in a case where the new system availability standard value is reset.

15. A computer readable storage medium encoded with a reliability evaluation program for an information system,

the reliability evaluation program, when executed by a computer, causing the computer to:

execute information input of input information necessary for reliability evaluation of the information system provided with an instrument, containing at least information concerning constituents indicating both software for executing a function of the instrument and hardware constituting the instrument, or concerning failures corresponding to failure modes of a constituent group formed of the constituents, system configuration information indicating information concerning a configuration of the information system employing the instrument and any of the constituents and the constituent group, and a standard value of system availability indicating availability of the entire information system;

analyze information on the failures of each of the failure modes of any of the constituents and the constituent group, and thereby obtaining analysis information thereon;

execute fault-tree production to produce a fault tree indicating hierarchical logical relationships from a top event indicating a failure mode of the information system to basic events indicating the failure modes of any of the constituents and the constituent group on the basis of the system configuration information;

execute unavailability calculation to calculate unavailability of any of the constituents and the constituent group corresponding to the failure modes of any of the constituents and the constituent group on the basis of the analysis information;

execute system availability calculation to calculate, on the basis of the fault tree and the unavailability corresponding to the basic events, availability corresponding to the top event as system availability in a case where it is supposed that the calculated unavailability is unavailability corresponding to the basic events equivalent to the failure modes of any of the constituents and the constituent group;

execute availability determination to determine whether or not the calculated system availability meets the standard value of the system availability;

execute basic event extraction to extract the basic event related to an increase in the system availability by use of a relationship between variation in the unavailability corresponding to the basic events and variation in the unavailability corresponding to the top event, in a case where it is determined that the calculated system availability does not meet the standard value;

execute first resetting to reset new analysis information corresponding to the extracted basic event in a case where it is possible to reduce the unavailability corresponding to the extracted basic event, and to reset new system configuration information and information concerning a failure corresponding to a new failure mode in a case where it is not possible to reduce the unavailability corresponding to the extracted basic event; and

execute the unavailability calculating process and the processes thereafter in a case where the new analysis information corresponding to the extracted basic event is reset, and executing the information analyzing process and the processes thereafter in a case where the information concerning a new failure in the failure mode corresponding to the extracted basic event is reset, and where the new system configuration information and the information concerning the failure corresponding to the new failure mode are reset.

16. A reliability evaluation system for an information system, comprising:

an information inputting unit to input information necessary for reliability evaluation of the information system provided with an instrument, containing at least information concerning constituents indicating both software for executing a function of the instrument and hardware constituting the instrument, or concerning failures corresponding to failure modes of a constituent group formed of the constituents, system configuration information indicating information concerning a configuration of the information system employing the instrument and any of the constituents and the constituent group, and a standard value of system availability indicating availability of the entire information system;

a memory to store the input information;

an information analyzing unit to analyze information stored in the memory on the failures of each of the failure modes of any of the constituents and the constituent group, thereby obtaining analysis information thereon, and storing the analysis information in the memory;

a fault-tree producing unit to produce a fault tree indicating hierarchical logical relationships from a top event indicating a failure mode of the information system to basic events indicating the failure modes of any of the constituents and the constituent group on the basis of the system configuration information stored in the memory;

an unavailability calculating unit to calculate unavailability of any of the constituents and the constituent group corresponding to the failure modes of any of the constituents and the constituent group on the basis of the analysis information stored in the memory;

a system availability calculating unit to calculate, on the basis of the fault tree and the unavailability corresponding to the basic events, availability corresponding to the top event as system availability in a case where it is supposed that the calculated unavailability is unavailability corresponding to the basic events equivalent to the failure modes of any of the constituents and the constituent group;

an availability determining unit to determine whether or not the calculated system availability meets the standard value of the system availability;

a basic-event extracting unit to extract the basic event related to an increase in the system availability by use of a relationship between variation in the unavailability corresponding to the basic events and variation in the unavailability corresponding to the top event, in a case where it is determined that the calculated system availability does not meet the standard value; and

a first resetting unit to reset new analysis information corresponding to the extracted basic event in a case where it is possible to reduce the unavailability corresponding to the extracted basic event, and to reset new system configuration information and information concerning a failure corresponding to a new failure mode in a case where it is not possible to reduce the unavailability corresponding to the extracted basic event.

17. A reliability evaluation system for an information system, comprising a processor programmed to:

input information necessary for reliability evaluation of the information system provided with an instrument, containing at least information concerning constituents indicating both software for executing a function of the instrument and hardware constituting the instrument, or concerning failures corresponding to failure modes of a constituent group formed of the constituents, system configuration information indicating information concerning a configuration of the information system employing the instrument and any of the constituents and the constituent group, and a standard value of system availability indicating availability of the entire information system;

analyze information on the failures of each of the failure modes of any of the constituents and the constituent group, and thereby obtaining analysis information thereon;

produce a fault tree indicating hierarchical logical relationships from a top event indicating a failure mode of the information system to basic events indicating the failure modes of any of the constituents and the constituent group on the basis of the system configuration information;

calculate unavailability of any of the constituents and the constituent group corresponding to the failure modes of any of the constituents and the constituent group on the basis of the analysis information;

calculate, on the basis of the fault tree and the unavailability corresponding to the basic events, availability corresponding to the top event as system availability in a case where it is supposed that the calculated unavailability is unavailability corresponding to the basic events equivalent to the failure modes of any of the constituents and the constituent group;

determine whether or not the calculated system availability meets the standard value of the system availability;

extract the basic event related to an increase in the system availability by use of a relationship between variation in the unavailability corresponding to the basic events and variation in the unavailability corresponding to the top event, in a case where it is determined that the calculated system availability does not meet the standard value;

reset new analysis information corresponding to the extracted basic event in a case where it is possible to reduce the unavailability corresponding to the extracted basic event; and

reset new system configuration information and information concerning a failure corresponding to a new failure mode in a case where it is not possible to reduce the unavailability corresponding to the extracted basic event.