🔴 Critical   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: RHEL 10

📖 ~1 min read

Table of contents
  1. Symptom & Impact
  2. Environment & Reproduction
  3. Root Cause Analysis
  4. Quick Triage
  5. Step-by-Step Diagnosis
  6. Solution – Primary Fix
  7. Solution – Alternative Approaches
  8. Verification & Acceptance Criteria
  9. Rollback Plan
  10. Prevention & Hardening
  11. Related Errors & Cross-Refs
  12. References & Further Reading

Symptom & Impact

SAN devices are missing at boot, resulting in unavailable filesystems and application downtime.

Environment & Reproduction

Observed on hosts connected to FC/iSCSI SAN when multipath config or startup order changed.

multipath -ll
lsblk
systemctl status multipathd

Root Cause Analysis

Invalid blacklists, outdated WWIDs, or services not starting early enough prevent mapper device creation.

Quick Triage

Check daemon and kernel discovery messages.

journalctl -u multipathd -b --no-pager | tail -n 80
dmesg | grep -Ei 'sd[a-z]|dm-|multipath'
systemctl is-enabled multipathd

Step-by-Step Diagnosis

Validate multipath config syntax and detected WWIDs.

multipath -t
cat /etc/multipath.conf
cat /etc/multipath/wwids
Illustrative mockup for rhel-10 — terminal_or_shell
Checking multipath status and WWIDs — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Correct config, rebuild initramfs if needed, and restart multipath daemon.

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sudo mpathconf --enable --with_multipathd y
sudo systemctl enable --now multipathd
sudo multipath -r
sudo dracut -f
Illustrative mockup for rhel-10 — log_or_config
Applying multipath configuration corrections — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Add explicit devices section for vendor/product-specific quirks.

sudo vi /etc/multipath.conf
sudo systemctl restart multipathd
multipath -ll

Verification & Acceptance Criteria

Expected `dm-*` maps appear and filesystems mount correctly.

multipath -ll
ls /dev/mapper
mount -a

Rollback Plan

Restore previous multipath config and boot with known-good kernel if needed.

sudo cp /etc/multipath.conf.bak /etc/multipath.conf
sudo systemctl restart multipathd

Prevention & Hardening

Version-control SAN host configs and test failover paths quarterly.

multipathd show paths
multipathd show maps

Related to missing FC zoning, stale iSCSI sessions, and udev timeout tuning issues.

Related tutorial: View the step-by-step tutorial for rhel-10.

View all rhel-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

RHEL DM-Multipath and SAN best-practice guides for enterprise storage deployments.

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