Date: Sat, 16 Dec 2023 21:25:11 +0100 From: "Patrick M. Hausen" <hausen@punkt.de> To: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org> Subject: Odd values for various memory metrics via SNMP Message-ID: <1EDAF2AC-3A2B-43BE-B66B-E095F5A80C2C@punkt.de>
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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)? Thanks and kind regards, Patrick --=20 punkt.de GmbH Patrick M. Hausen .infrastructure Sophienstr. 187 76185 Karlsruhe Tel. +49 721 9109500 https://infrastructure.punkt.de info@punkt.de AG Mannheim 108285 Gesch=C3=A4ftsf=C3=BChrer: Daniel Lienert, Fabian Stein
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