Proxmox status.Mem includes page cache as "used" memory, inflating
reported VM usage. The existing fallbacks (balloon meminfo, RRD, linked
host agent) were frequently unavailable, causing most VMs to fall
through to the inflated status-mem source.
Adds a new last-resort fallback that reads /proc/meminfo via the QEMU
guest agent file-read endpoint to get accurate MemAvailable. Results
are cached (60s positive, 5min negative backoff for unsupported VMs).
Also fixes: RRD memavailable fallback missing from traditional polling
path, cache key collisions in multi-PVE setups, FreeMem underflow
guard inconsistency, and integer overflow in kB-to-bytes conversion.
Linux VM page cache (#1270): QEMU VM memory now falls back to Proxmox
RRD's memavailable metric (which excludes reclaimable page cache) when
the qemu-guest-agent doesn't provide MemInfo.Available. Previously the
fallback was detailedStatus.Mem (total - MemFree), inflating usage to
80%+ on VMs with normal Linux page cache. Mirrors the existing LXC
rrd-memavailable path.
FreeBSD ZFS ARC (#1264, #1051): The host agent now reads
kstat.zfs.misc.arcstats.size via SysctlRaw on FreeBSD and subtracts
the ARC size from reported memory usage. ZFS ARC is reclaimable under
memory pressure (like Linux SReclaimable) but gopsutil counts it as
wired/non-reclaimable, causing false 90%+ memory alerts on TrueNAS
and FreeBSD hosts. Build-tagged so it compiles cleanly on all platforms.
Fixes#1270Fixes#1264Fixes#1051
(cherry picked from commit 94502f83ff9ffc6da28aaadc946a2f7d8b4e9bac)
- Fix TestMonitor_PollGuestSnapshots_Coverage by correctly initializing State ID fields
- Improve PBS client to handle alternative datastore metric fields (total-space, etc.)
- Add comprehensive test coverage for PBS polling, auth failures, and datastore metrics
- Add various coverage tests for monitoring, alerts, and metadata handling
- Refactor Monitor to support better testing of client creation and auth handling
