What is performance counter rollover? How do we determine the maximum value for a counter?

[mitchellcipriano]

What is performance counter rollover? How do we determine the maximum value that can be returned for a counter. E.g read_data or read_latency what are the maximum values that would be returned ?

[ingolantschner]

There is a PDF document with a table for DataONTAP 7.3 (sic!) stating that read_data has a size of 8B. So probably the size is 8 Bytes. But it would be nice to get this confirmed and updated from NetApp!

Douments name and chapter is:  NetApp® Unified Storage Performance Management Using Open Interfaces, Appendix 1 - Performance counters in Data ONTAP 7.3