[+joel]

On Tue, Jun 19, 2012 at 2:11 PM, Seth Wright <[email protected]> wrote:
> I kind of thought the UCD-SNMP-MIB was fairly standard and/or
> widespread, but perhaps not?

HOST-RESOURCES-MIB is an RFC standard, which I assume gives it more
stature than UCD-SNMP-MIB, but I honestly haven't used SNMP much in
the last few years, so I'm not the best person to make a decision
here.

> * HR-MIB includes hrProcessorLoad which is a percentage-based value
> for each CPU (if I'm reading the MIB right) for the one-minute
> timeframe.  UCD-SNMP presents 1-, 5-, and 15-minute aggregate values,
> which may be more useful.

I think you're referring to how UCD-SNMP-MIB exposes 1, 5, and 15
minute load averages, which are different from CPU utilization.  In
particular, it tends to be a common source of confusion among users
because OpenBSD calculates load averages very differently than other
operating systems (e.g.,
http://www.undeadly.org/cgi?action=article&sid=20090715034920&mode=expanded).

You should be able to calculate 5 and 15 minute rolling averages in
your SNMP monitoring software too.

> * HR-MIB, under the hrStorage* attributes, includes free and used
> values for memory, but doesn't get any more granular than that.
> UCD-SNMP tries to break it down a bit further.

That's valid, though I believe we could expose much more fine grained
memory via HOST-RESOURCES-MIB too.  E.g., buffer cache, kernel pool(9)
and malloc(9) buckets, and so on.

I'm not sure off hand if the memory groups in UCD-SNMP-MIB maps well
to our VM system either, but I guess they all say they can be left out
if the OS doesn't support the category.

> * UCD-SNMP includes a bunch of CPU stats that I'm only starting to
> look at (the third "blank graph" in my monitoring templates) that I
> can't find in a walk against base snmpd.  Those were going to be in
> diff number next.

These might be interesting, and it's data not exposed otherwise
currently.  The closest HOST-RESOURCES-MIB has is hrSWRunPerfCPU and
hrSWRunPerfMem, but those don't track interrupt CPU usage.

> So yes, I think it does provide some value over what's already in
> there, but that's just the opinion of a guy scratching a proverbial
> itch.

Understood, I'm just trying to make sure the diff makes sense to be
committed.

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