Patent Number: 
Section: claims

1. A control system comprising:a control computer; anda computer monitored by said control computer;wherein said control computer includes:an interface for receiving an operation performance metric value of each of a plurality of first monitored items from said monitored computer, anda control section for, based on said operation performance metric value of said each first monitored item, determining a second monitored item and issuing an acquisition instruction instructing said monitored computer to obtain an operation performance metric value of said second monitored item, said second monitored item being associated with said each first monitored item; andwherein said monitored computer includes:an interface for receiving said acquisition instruction from said control computer, anda control section for, based on said acquisition instruction, obtaining said operation performance metric value of said second monitored item and transmitting it to said control computer,wherein when said operation performance metric value of said each first monitored item is within a risk range, the number of second monitored items is increased, thereby intensively monitoring closely related monitored items, andwherein when said operation performance metric value of said each first monitored item is outside of the risk range, the number of second monitored items is reduced, thereby not intensively monitoring closely related monitored items. 2. The control system as claimed in claim 1, wherein said control section of said control computer determines said second monitored item based on an expected value calculated by use of said operation performance metric value of said each first monitored item, said second monitored item being associated with said each first monitored item. 3. The control system as claimed in claim 2, wherein said expected value is calculated based on said operation performance metric value of said each first monitored item by assuming that acquisition of said expected value and that of said operation performance metric value of said each first monitored item fall on either a same hour, a same day of the week, a same date, or a same month, said operation performance metric value of said each first monitored item being previously obtained. 4. The control system as claimed in claim 1, wherein a plurality of said second monitored items are employed. 5. The control system as claimed in claim 4, wherein:priority is given to each of said second monitored items; andsaid control section of said control computer determines said second monitored item based on said priority. 6. The control system as claimed in claim 1, wherein said control section of said control computer determines a degree of risk of said control system based on said operation performance metric value of said each first monitored item and determines a second monitored item based on said degree of risk, said second monitored item being associated with said each first monitored item. 7. The control system as claimed in claim 1, wherein said control section of said control computer determines a degree of risk of said control system based on said operation performance metric value of said each first monitored item, determines a second monitored item and an acquisition interval based on said degree of risk, and issues an acquisition instruction instructing said monitored computer to obtain an operation performance metric value of said second monitored item at said determined acquisition intervals, said second monitored item being associated with said each first monitored item. 8. The control system as claimed in claim 1, wherein each monitored item includes information indicating the type of a performance characteristic of at least one of an application server, a database server, a storage device, and a program. 9. The control system as claimed in claim 1, wherein said performance characteristic includes information indicating at least one of a CPU usage rate, a memory usage rate, and a disk usage rate. 10. The control system as claimed in claim 1, wherein the second monitored items are different from the first monitored items. 11. The control system as claimed in claim 1, wherein a number of the second monitored items are increased from a number of the first monitored items. 12. The control system as claimed in claim 1, wherein a number of the second monitored items are decreased from a number of the first monitored items. 13. A control system comprising:a control computer; and a computer monitored by said control computer;wherein said monitored computer includes:a control section for, based on an operation performance metric value of each of a plurality of first monitored items, determining a second monitored item and obtaining an operation performance metric value of said second monitored item, said second monitored item being associated with said each first monitored item, andan interface for transmitting said obtained operation performance metric value; andwherein said control computer includes:an interface for receiving said operation performance metric value from said monitored computer, anda control section for monitoring an operational state of a system based on said operation performance metric value,wherein when said operation performance metric value of said each first monitored item is within a risk range, the number of second monitored items is increased, thereby intensively monitoring closely related monitored items, andwherein when said operation performance metric value of said each first monitored item is outside of the risk range, the number of second monitored items is reduced, thereby not intensively monitoring closely related monitored items. 14. The control system as claimed in claim 13, wherein the second monitored items are different from the first monitored items. 15. The control system as claimed in claim 13, wherein a number of the second monitored items are increased from a number of the first monitored items. 16. The control system as claimed in claim 13, wherein a number of the second monitored items are decreased from a number of the first monitored items. 17. A control computer for monitoring an operational state of a system, comprising:an interface for receiving an operation performance metric value of each of a plurality of first monitored items from a monitored computer; anda control section for, based on said operation performance metric value of said each first monitored item, determining a second monitored item and instructing said monitored computer to obtain an operation performance metric value of said second monitored item, said second monitored item being associated with said each first monitored item,wherein when said operation performance metric value of said each first monitored item is within a risk range, the number of second monitored items is increased, thereby intensively monitoring closely related monitored items, andwherein when said operation performance metric value of said each first monitored item is outside of the risk range, the number of second monitored items is reduced, thereby not intensively monitoring closely related monitored items. 18. The control computer as claimed in claim 17, wherein a number of the second monitored items are increased from a number of the first monitored items. 19. The control computer as claimed in claim 17, wherein a number of the second monitored items are decreased from a number of the first monitored items. 20. The control computer as claimed in claim 17, wherein the second monitored items are different from the first monitored items. 21. A control method for monitoring an operational state of a system, comprising the steps of:based on an operation performance metric value of each of a plurality of first monitored items received from a monitored computer object, determining a second monitored item, said second monitored item being associated with said each first monitored item;instructing said monitored computer to obtain an operation performance metric value of said second monitored item; andsending the obtained performance metric value to a monitoring computer, thereby permitting the operational state of the system to be monitored,wherein when said operation performance metric value of said each first monitored item is within a risk range, the number of second monitored items is increased, thereby intensively monitoring closely related monitored items, andwherein when said operation performance metric value of said each first monitored item is outside of the risk range, the number of second monitored items is reduced, thereby not intensively monitoring closely related monitored items. 22. The control computer as claimed in claim 21, wherein a number of the second monitored items are decreased from a number of the first monitored items. 23. The control method as claimed in claim 21, wherein a number of the second monitored items are increased from a number of the first monitored items. 24. The control method as claimed in claim 21, wherein the second monitored items are different from the first monitored items. 25. A control program, stored on a storage medium, for monitoring an operational state of a system, said control program, when executed, causes a computer to perform the steps of:based on an operation performance metric value of each of a plurality of first monitored items received from a monitored computer object, determining a second monitored item, said second monitored item being associated with said each first monitored item; andinstructing said monitored computer to obtain an operation performance metric value of said second monitored item and to send the obtained performance metric value to a monitoring computer,wherein when said operation performance metric value of said each first monitored item is within a risk range, the number of second monitored items is increased, thereby intensively monitoring closely related monitored items, andwherein when said operation performance metric value of said each first monitored item is outside of the risk range, the number of second monitored items, thereby not intensively monitoring closely related monitored items. 26. The control program as claimed in claim 25, wherein a number of the second monitored items are decreased from a number of the first monitored items. 27. The control program as claimed in claim 25, wherein a number of the second monitored items are increased from a number of the first monitored items. 28. The control program as claimed in claim 25, wherein the second monitored items are different from the first monitored items.