topic Aggregate used and committed values in OCUM versus NMSDK? in Active IQ Unified Manager Discussions

Aggregate used and committed values in OCUM versus NMSDK?

WAFLHERDER — Wed, 04 Jun 2025 13:07:24 GMT

Hi All,

I noticed that OCUM can generate used and committed values for aggregate capacity and I want to do something similar using the Management SDK, but I cannot figure out how ...

I took a look at the management SDK documentation and the recommended API call for getting aggregate space information, aggr-space-get-iter(). It seems to be capable of returning a lot of different attributes, but nothing that is obviously (to me) related to the committed space.

Or, perhaps OCUM is generating the committed values in some other way e.g. by summing up values for some volume attribute, for all the vols contained within an aggregate?

My goal is to just gather some simple usage info. for the storage management team:

- What size are the (data) aggregates

- How much of each aggregate is in use

- How much of each aggregate has been "given out" / allocated to user volumes / committed

Thanks in advance for your feedback!

BTW, looking at the returned attributes from the above API call, what is an "object store"? I.e. I see attributes with names like "object-store-size" ... is that an aggregate, or some other construct contained within an aggregate?

Cheers,

Robb.

Re: Aggregate used and committed values in OCUM versus NMSDK?

niels — Fri, 23 Nov 2018 14:27:51 GMT

Hi WAFLHERDER,

OCUM uses a relatively simple metric to calculate the committed space. Personally I find it not to be too useful, but it may help, depending on what you are actually after or how your volumes are configured.

OCUM commited aggregate space usage:

sum of all volumes within an aggregate with their respective maximum auto-grow size

As the max autogrow size can vary between "actual" volume size and 100TB (the maximum FlexVol size) for each volume the number OCUM presents you maybe way off of what you would expect.

You may have to wite your own script that just summarizes actual volumes sizes and compare the sum to the actual capacity of the aggregate to get to a more meaningful overcommit ratio.

Regarding "object store" - with recent ONTAP versions you can attach an S3 target to an aggregate. ONTAP will tier cold data within an aggregate to that object tier - transparently to the user. The API will return capacity information of that object tier as it's an integral part of the aggregate.

That feature is called "FabricPool".

regards, Niels