Gauge for monitoring instances of a storage system event

1. A method for monitoring a storage system event, the method comprises:

receiving, by a control unit of a storage system, a request to access a gauge that is associated with the storage system event;

updating, by the control unit, a value of the gauge based on (a) a time difference between a time related to the request to access the gauge and a time related to a previous request to access the gauge, and (b) a length of a sliding time window;

wherein the value of the gauge provides an approximation of an average rate of instances of the storage system event during the sliding time window; and

wherein when the request to access the gauge is triggered by an occurrence of an instance of the storage system event then the updating further includes updating the value of the gauge to increase the approximation of the average rate of instances of the storage system event, so as to reflect the occurrence of the instance of the storage system event.

2. The method according to claim 1 wherein when the request to access the gauge is a read request then reading the value of the gauge after the updating of the value of the gauge.

3. The method according to claim 1 wherein the previous request to access the gauge and the request to access the gauge are consecutive requests to access the gauge.

4. The method according to claim 1 , comprising updating the value of the gauge to reduce the approximation of the average rate using an exponential value that reflects the time difference and the length of the sliding time window.

5. The method according to claim 1 , comprising updating the value of the gauge to reduce the approximation of the average rate using an exponential value that reflects a ratio between the time difference and the length of the sliding time window.

6. The method according to claim 1 , wherein the updating of the value of the gauge comprises:

multiplying the value of the gauge by an exponential value that has a base and an exponent, wherein the base equals e and the exponent equals −DeltaT/W, wherein DeltaT is the time difference and W is the length of the sliding time window.

7. The method according to claim 1 , wherein when the accessing of the gauge is triggered by the occurrence of the instance of the storage system event then the updating of the value of the gauge to increase the approximation of the average rate is based on the length of the sliding time window.

8. The method according to claim 1 , wherein when the accessing of the gauge is triggered by the occurrence of the instance of the storage system event then the method comprises increasing the value of the gauge by 1/W, wherein W is the length of the sliding time window.

9. The method according to claim 1 , wherein when the request to access the gauge is a read request then the method comprises reacting to the value of the gauge.

10. The method according to claim 1 , comprising reacting to the value of the gauge by enforcing a service level agreement that is related to the storage system event.

11. The method according to claim 1 , comprising reacting to the value of the gauge by restricting an access to a storage system entity related to the storage system event that when completed will violate a service level agreement that is related to the storage system entity.

12. The method according to claim 1 , wherein when the request to access the gauge is triggered by occurrences of multiple instances of the storage system event then the updating further includes updating the value of the gauge to increase the approximation of the average rate of instances of the storage system event, so as to reflect the occurrences of the multiple instances of the storage system events.

13. The method according to claim 1 , comprising monitoring storage system events of different types;

wherein the method comprises allocating different gauges to different types of storage system events;

wherein the method comprises executing, for each gauge, the steps of:

receiving, by the control unit of the storage system, a request to access the gauge;

updating, by the control unit, a value of the gauge in response to the request to access;

wherein the updating comprises updating the value of the gauge based on (a) a time difference between a time related to the request to access the gauge and a time related to a previous request to access the gauge, and (b) a length of a sliding time window;

wherein the value of the gauge provides an approximation of an average rate of instances of storage system event of the type that is associated with the gauge per the sliding time window; and wherein when the request to access the gauge is triggered by an occurrence of an instance of a storage system event of a type that is associated with the gauge then the updating further includes updating the value of the gauge to increase the approximation of the average rate of instances of the storage system event, so as to reflect the occurrence of the instance of the storage system event of the type that is associated with the gauge;

and

wherein the request to access the gauge is a read request then reading the value of the gauge after the updating of the value of the gauge.

14. The method according to claim 13 , the method comprises performing memory management operations based on values of the different gauges.

15. A non-transitory computer program product that stores instructions that once executed by a control unit of a storage system, cause the storage controller to execute the steps of: receiving a request to access a gauge that is associated with a storage system event; updating a value of the gauge based on (a) a time difference between a time related to the request to access the gauge and a time related to a previous request to access the gauge, and (b) a length of a sliding time window; wherein the value of the gauge provides an approximation of an average rate of instances of the storage system event during the sliding time window; and wherein when the request to access the gauge is triggered by an occurrence of an instance of the storage system event then the updating further includes updating the value of the gauge to increase the approximation of the average rate of instances of the storage system event, so as to reflect the occurrence of the instance of the storage system event.

16. A storage system comprising a control unit that is configured to receive a request to access a gauge that is associated with a storage system event; update, by the control unit, a value of the gauge based on (a) a time difference between a time related to the request to access the gauge and a time related to a previous request to access the gauge, and (b) a length of a sliding time window; wherein the value of the gauge provides an approximation of an average rate of instances of the storage system event during the sliding time window; and wherein when the request to access the gauge is triggered by an occurrence of an instance of the storage system event then the updating further includes updating the value of the gauge to increase the approximation of the average rate of instances of the storage system event, so as to reflect the occurrence of the instance of the storage system event.