Sinhaa -
OC-API Services has plusses and minuses, like anything. You are correct that it takes another resource, but in this case it's a fairly low maintenance resource once configured.
The key benefit is that you have a single source from which to collect data. For example, in my environment I have 3x OPM servers pushing events to 1x OCUM server. Because my clusters are in geograhphically diverse locations (multiple continents) the OPM collection works better locally, while the single OCUM handles the general collection with ease. But, that means four OC-servers from which to collect data for add-on applications. It could have just as easily been 3 separate OCUM/OPM pairs - six separate collection points.
The advantage of OC-API Services is not readily apparent if you have just one OCUM/OPM pair. As the environment grows, it is simpler to write collection scripts against one central collection point. OC-API also presents a REST API which is easy to integrate into most environments without worrying about direct acces to the underlying OCUM/OPM MySQL databases.
OC-API doesn't store any data - it just gathers it from the OCUM/OPM servers it fronts on demand. It also adds group level authentication for those environments that would like to use it. Using OC-API you can also centralize authentication at a single server for a wider audience if you so choose.
For complete collected data you would still need to go to the OCUM/OPM databases directly. But for all the general counters that DFM provided, OC-API will do the job quite nicely. I was headed down the direct database access route myself for a number of standard performance analysis scripts I use, but quickly converted them all to the API Services when that became available.
Hope this helps answer your question.
Bob Greenwald
Lead Storage Engineer
Huron Consulting Group
NCDA, NCIE-SAN Clustered Data Ontap
