wiki: add 1 vCPU nice/ionice limitation note to ClamAV article

nice -n 19 only yields when other processes compete; on single-core
VPS boxes the scan still saturates CPU. Document the expectation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

05-troubleshooting/security/clamscan-cpu-spike-nice-ionice.md

@@ -1,11 +1,17 @@
 ---
-title: "ClamAV Safe Scheduling on Live Servers"
+title: ClamAV Safe Scheduling on Live Servers
 domain: troubleshooting
 category: security
-tags: [clamav, cpu, nice, ionice, cron, vps]
+tags:
+  - clamav
+  - cpu
+  - nice
+  - ionice
+  - cron
+  - vps
 status: published
 created: 2026-04-02
-updated: 2026-04-02
+updated: 2026-05-11T18:31
 ---
 # ClamAV Safe Scheduling on Live Servers
 
@@ -75,6 +81,7 @@ kill <PID>
 - `ionice -c 3` (Idle) requires Linux kernel ≥ 2.6.13 and CFQ/BFQ I/O scheduler. Works on most Ubuntu/Debian/Fedora systems.
 - On multi-core servers, consider also using `cpulimit` for a hard cap: `cpulimit -l 30 -- clamscan ...`
 - Always keep `--exclude=/sys` (and optionally `--exclude=/proc`, `--exclude=/dev`) to avoid scanning virtual filesystems.
+- **1 vCPU limitation:** `nice` and `ionice` only help when other processes compete for resources. On a single-core VPS, clamscan will still saturate the CPU at 57-100% even with `nice -n 19 ionice -c 3` — there's nothing to yield to. Accept the weekly spike as benign, or reduce scan scope to shorten the window.
 
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