CachyOS Mirror Timer: Why Your Updates Crawl and the 10-Second Fix

On CachyOS (and Arch derivatives), cachyos-rate-mirrors ranks Arch and CachyOS mirrors by speed and rewrites /etc/pacman.d/mirrorlist and /etc/pacman.d/cachyos-mirrorlist. It is the difference between 20 MB/s downloads and 400 KB/s — or outright failures.

The Problem

My pacman updates had been crawling. pacman -Syu would hang on “synchronizing package lists” or time out on specific mirrors. The mirrorlists were stale:

# /etc/pacman.d/mirrorlist (before)
# Singapore Arch Linux Mirrors
Server = https://singapore.mirror.pkgbuild.com/$repo/os/$arch
Server = https://sg.arch.niranjan.co/$repo/os/$arch

# /etc/pacman.d/cachyos-mirrorlist (before)
# CachyOS CDN (Routes to Singapore)
Server = https://cdn77.cachyos.org/repo/$arch/$repo

Only 2 Arch mirrors and 1 CachyOS mirror. If either Singapore mirror had issues, updates stalled.

Root Cause

The systemd timer that runs cachyos-rate-mirrors defaults to every 10 days:

# /usr/lib/systemd/system/cachyos-rate-mirrors.timer
[Timer]
OnUnitActiveSec=10d
RandomizedDelaySec=6h
Persistent=true

systemctl list-timers confirmed it last ran on June 3 — two weeks ago. Ten days is too long for rolling-release mirror churn.

The Fix: Systemd Drop-In (Survives Updates)

Instead of editing the package file (which pacman -Syu overwrites), create a drop-in:

sudo mkdir -p /etc/systemd/system/cachyos-rate-mirrors.timer.d
printf '[Timer]\nOnUnitActiveSec=7d\nRandomizedDelaySec=6h\n' \
  | sudo tee /etc/systemd/system/cachyos-rate-mirrors.timer.d/override.conf >/dev/null
sudo systemctl daemon-reload

Verify:

systemctl cat cachyos-rate-mirrors.timer

Output shows the override at the bottom:

# /usr/lib/systemd/system/cachyos-rate-mirrors.timer
[Timer]
OnUnitActiveSec=10d
RandomizedDelaySec=6h
Persistent=true

# /etc/systemd/system/cachyos-rate-mirrors.timer.d/override.conf
[Timer]
OnUnitActiveSec=7d
RandomizedDelaySec=6h

Immediate Relief

Run it manually once:

sudo cachyos-rate-mirrors

Now both mirrorlists populate with 30+ working mirrors:

# /etc/pacman.d/mirrorlist (after)
Server = https://mirror.sahil.world/archlinux/$repo/os/$arch
Server = https://geo.mirror.pkgbuild.com/$repo/os/$arch
Server = https://singapore.mirror.pkgbuild.com/$repo/os/$arch
... 30 more ...

# /etc/pacman.d/cachyos-mirrorlist (after)
Server = https://cdn77.cachyos.org/repo/$arch/$repo
Server = https://mirror2.keiminem.com/cachyos/repo/$arch/$repo
Server = https://mirror.hb9hil.org/cachyos/repo/$arch/$repo
... 11 more ...

Next pacman -Syu completes in seconds.

Why This Doesn’t Break Upstream

Concern	Reality
Mirror hammering	`rate-mirrors` does HEAD requests (~1 KB each). 30 mirrors × 2 repos = negligible load.
Upstream rate limits	None — mirrors are public CDN endpoints designed for this.
Package updates overwrite fix	Drop-in at `/etc/systemd/system/...` takes precedence over `/usr/lib/...`. `pacman` never touches `/etc/systemd/system/`.
Timer drift	`RandomizedDelaySec=6h` spreads load across the day; `Persistent=true` catches up if machine was off.

Evidence Table

Metric	Before (10d timer)	After (7d timer + manual run)
Arch mirrors in list	2	34
CachyOS mirrors in list	1	14
`pacman -Syu` sync time	30–60 s (often timeout)	< 3 s
Failed mirror connections	Frequent	Zero

TL;DR

# One-liner (fish)
sudo mkdir -p /etc/systemd/system/cachyos-rate-mirrors.timer.d; printf '[Timer]\nOnUnitActiveSec=7d\nRandomizedDelaySec=6h\n' | sudo tee /etc/systemd/system/cachyos-rate-mirrors.timer.d/override.conf >/dev/null; sudo systemctl daemon-reload; sudo cachyos-rate-mirrors

Rolling release = rolling mirrors. The default 10-day cadence assumes static infrastructure. It isn’t. Seven days keeps mirrorlists fresh without burdening anyone.