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Document TCP BBR + Apache keepalive tuning (Nextcloud throughput follow-up)

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Claudio
2026-05-13 21:22:17 +02:00
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hosts/hubris.md
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@@ -31,6 +31,7 @@ See [containers/index](../containers/index.md). 14 active, 1 stopped.
## Boot-time tuning (load-bearing)
- **TCP BBR + `fq` qdisc** in `/etc/sysctl.d/99-bbr.conf`: `net.ipv4.tcp_congestion_control=bbr`, `net.core.default_qdisc=fq`, socket buffers up to 64 MiB (`rmem_max`/`wmem_max`/`tcp_rmem`/`tcp_wmem`). `tcp_bbr` module pinned to load at boot via `/etc/modules-load.d/bbr.conf`. Improves single-TCP-stream throughput on jittery / lossy links (notably WiFi clients downloading from [114 — nextcloud](../containers/114-nextcloud.md)). Container traffic crosses this kernel, so every guest inherits the change.
- **`cpu-epp.service`** (enabled) sets `scaling_governor=powersave` + EPP=`balance_power` at boot — drops idle Tctl from ~95 °C → ~60 °C, clocks from 4.4 GHz pinned → 1.1–2 GHz idle. In `amd-pstate=active` mode the governor MUST be `powersave`, not `performance`, for EPP to apply. Unit ordering: `After=sysinit.target` + `Before=pve-guests.service` so it runs before the guest fleet starts (the original `After=multi-user.target` left the hottest boot window on `performance`). Fixed 2026-04-22.
- **Crash capture:** `/etc/sysctl.d/60-crash-capture.conf` (panic on oops/hardlockup/softlockup/rcu, auto-reboot 10 s), `/etc/modprobe.d/softdog.conf` (`soft_panic=1 soft_margin=60`), `/etc/systemd/system.conf.d/watchdog.conf` (`RuntimeWatchdogSec=15s`). Pstore traces collected to `/var/lib/systemd/pstore/` by `systemd-pstore.service`. **Caveat:** silent CPU lockups leave pstore empty.
- **`rasdaemon`** (Debian pkg) collects MCE / memory / PCIe AER / thermal events to `/var/lib/rasdaemon/ras-mc_event.db`. Query with `ras-mc-ctl --summary` / `--errors`. (mcelog is retired in Debian 13 — don't go looking for it.)
@@ -85,6 +86,9 @@ OpenSSH on `0.0.0.0:22`. Netbird's built-in SSH server is on `100.122.38.109:220
## Changelog
### 2026-05-13 — TCP BBR + fq qdisc enabled
`/etc/sysctl.d/99-bbr.conf` switches `net.ipv4.tcp_congestion_control` from `cubic` to `bbr` and `net.core.default_qdisc` from `fq_codel` to `fq`. Also bumps `rmem_max`/`wmem_max` to 64 MiB and widens `tcp_rmem`/`tcp_wmem`. `tcp_bbr` module pinned at boot via `/etc/modules-load.d/bbr.conf`. Triggered by Nextcloud client downloads from a WiFi laptop pulling ~2 MB/s despite a 152 Mbps link — server-side baseline through Caddy with BBR is ~400 MB/s single-stream loopback, so any client-perceived single-stream improvement is pure congestion-control win. Touches every LXC's outbound TCP since they all share this kernel.
### 2026-04-29 — relocated to better-ventilated spot
User physically moved the host to a new location with improved airflow. Post-move idle baseline (45 min uptime, light load): k10temp Tctl **47.2 °C**, amdgpu edge 42 °C, nvme0 composite 34.9 °C / sensor1 32.9 °C, nvme1 composite 38.9 °C / sensor1 52.9 °C, DRAM 34–35.5 °C, ACPI zone 47–49 °C. Compares well against the 2026-04-23 thermal-pad steady-state (nvme0 sensor1 60–61 °C). Watch the lifetime NVMe warning-time counter over the coming days for confirmation. See [investigation](../investigations/2026-04-21-hubris-crash-loop.md#2026-04-29-physical-relocation).