Date: Tue, 19 Dec 2023 15:50:21 +0700 From: Yuri <yuri@aetern.org> To: "Patrick M. Hausen" <hausen@punkt.de>, FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: Odd values for various memory metrics via SNMP Message-ID: <de2988a0-00d6-4b4b-8150-bfa235649d64@aetern.org> In-Reply-To: <1EDAF2AC-3A2B-43BE-B66B-E095F5A80C2C@punkt.de> References: <1EDAF2AC-3A2B-43BE-B66B-E095F5A80C2C@punkt.de>
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Patrick M. Hausen wrote: > Hi all, > > what's the best platform/list/forum/... to discuss issues with the SNMP implementations > for FreeBSD? Since I started to dig deeper into Obervium I found that of all the systems > I own only the FreeBSD based ones present some challenges regarding the interpretation > of memory metrics. > > 1. I confirmed that this is not an Observium artefact. LibreNMS and manual snmpwalk > give the same results. > > 2. This is independent of the question if you use net-snmp (FreeNAS, OPNsense) or > bsnmpd in base (my Raspberry Pi cluster). > > 3. These are the systems concerned: > > - OPNsense - FreeBSD 13.2, AMD64, 8 G of RAM, net-snmp > - FreeNAS - TrueANS CORE, FreeBSD 13.1, AMD64, 64 G of RAM, net-snmp > - 7 Raspberry Pi CM 3+, AARCH64, 1 G of RAM, bsnmpd > > 4. The "odd" metrics: > > - "Real Memory" > > OPNsense: 762 of 768 M (yes!) used, flagged "red" in Observium, of course > FreeNAS: 35.9 of 36.1 G used > All the Pis: 178 of 179 M used > > All - see hardware description above - no connection to the "real real" memory installed. > > For comparison: ESXi 8.0: 26.7 of 31.9 G used - the system has got 32 G of RAM installed. > > - "Shared real memory" > > OPNsense: 97.1 of 103 M used > FreeNAS: 593 of 774 M used > Pis: 11.8 of 12.4 M used > > - Shared virtual memory > > Only systems running net-snmp have this, bsnmpd based ones don't. > > OPNsense: 166 of 233 M used > FreeNAS: 1028.27 M of 1.49 G used > > - Virtual Memory > > Again, only via net-snmp. > > OPNsense: 5.03 of 5.11 G used > FreeNAS: 628 of 628 G used - that's particularly weird for a system with 64 G of RAM > installed and not swapping or anything. > > For comparison: my only Linux based system: 12.7 of 29.6 G used - the system has > 16 G of RAM plus 16 G of swap, that seems to match the "29.6". > > > For me these numbers don't make any sense at all. The motivation to write this email: > I am planning to use SNMP based monitoring, probably Observium, for all our data > centres, which means > 100 FreeBSD based hosts. The point of a monitoring/management > system is that anything flagged "red" is a real problem that needs attention and the default > state should be "everything super green". Things flagged "red" but "everybody knows > it can be ignored" bind a huge amount of brain capacity on behalf of the operators. Not good. > > > So what is going on here? What do these numbers actually mean? Where do they come > from? Are they artefacts of the SNMP implementation not taylored perfectly for FreeBSD > or are they some real metric that ends up interpreted wrong in the NMS (Observium)? Let's start with OIDs, which ones exactly you are looking at (numeric or textual will do)?
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