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

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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>
This commit is contained in:
Marcus Summers 2026-05-11 18:32:01 -04:00
parent 3df0979786
commit ac84610380
1 changed files with 10 additions and 3 deletions
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05-troubleshooting/security/clamscan-cpu-spike-nice-ionice.md
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@ -1,11 +1,17 @@
--- ---
title: "ClamAV Safe Scheduling on Live Servers" title: ClamAV Safe Scheduling on Live Servers
domain: troubleshooting domain: troubleshooting
category: security category: security
tags: [clamav, cpu, nice, ionice, cron, vps] tags:
- clamav
- cpu
- nice
- ionice
- cron
- vps
status: published status: published
created: 2026-04-02 created: 2026-04-02
updated: 2026-04-02 updated: 2026-05-11T18:31
--- ---
# ClamAV Safe Scheduling on Live Servers # 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. - `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 ...` - 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. - 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.
## Related ## Related