Version

Argent AT 5.1A-1707-A or below

Date

Wednesday, 9 August 2017

Summary

When monitoring the delta value of an SNMP counter, if the counter value exceeds 8 digits, the delta value can randomly show a very large positive number, such as 4,294,967,295, which is 2³²-1.

Technical Background

The Argent AT engine saves the last poll value in the SQL table ARGSOFT_{PRODUCT}_PERF_LAST_VALUE.

The value is retrieved and compared with the current value to calculate the delta value.

In Argent AT 5.1A-1707-A or below, the data type of the SQL column saving the metric is ‘real’, which is functionally identical to float(4).

A ‘real’ field has precision of about 7 digits.

When the SNMP counter value reaches 8 digits, the last digit is not accurate any more. If the actual increment of SNMP counter is less than 10, the delta becomes random between -9 to 9. If it happens to be negative, it is translated into a huge positive number when being saved as Argent Predictor data.

To resolve the issue, the SQL column type is changed to float(53), which has precision of about 15 digits and consistent with the double type in C/C++.

Resolution

Upgrade to Argent AT 5.1A-1707-B or above.

For customers who encounters such an issue and cannot upgrade immediately, contact Argent support to adjust the SQL column type in affected SQL tables.