nfs-cifs-mount-diagnose

# NFS / CIFS mount diagnosis Troubleshoot NFS or CIFS/SMB mount failures, boot-time automount failures, and permission denials on **this host**. **Out of scope**: automatically running `mount`/`umount`, editing fstab, or calling cloud NAS APIs. Suggest only; write actions need explicit user confirmation. ## Rules 1. **Collect first**: protocol (NFS/CIFS), server, export/share path, full error text, mount command used. 2. **Read-only first**: modules, network, current mounts, fstab—do not mount on your own. 3. **Match error patterns early**: treat them as **candidates**, then verify. 4. **Stop when enough**: stop once the likely root cause is clear. 5. **No secrets in chat**: do not paste passwords or `password=` / `credentials=` options. ## Workflow ```text Collect info → error pattern match → client environment → connectivity → recommendations ``` ### 1. Collect info | Item | Example | |------|---------| | Protocol | NFS v3/v4 or CIFS/SMB | | Server | `files.example.com` or IP | | Remote path | NFS `:/export/data`; CIFS `//server/share` | | Full error | whole `mount.nfs: ...` / `mount error(13): ...` line | | Context | manual / fstab at boot / inside container | ### 2. Error patterns (prefer these) #### NFS | Error / symptom | Common cause | Direction | |-----------------|--------------|-----------| | `access denied by server while mounting` (esp. with a **subdirectory** path) | Export/ACL/IP, wrong path, or missing subdir | Do not assume “subdir missing” from the message alone; check exports (`showmount -e`), then the path | | `mount.nfs: No such device` | `nfs`/`sunrpc` not loaded, or bad sunrpc option spelling | Check `lsmod`, `/etc/modprobe.d/*sunrpc*`; use `tcp_slot_table_entries` not `tcp_slot_entries` | | `Operation not permitted` on NFSv4 while v3 works | NFSv4 client id / hostname conflict, etc. | Try v3 to confirm; check hostname / nfs4 unique id; check server exports | | `Connection timed out` / `No route to host` | Network, firewall, NFS/RPC ports | `ping` / 2049 / 111 before tuning mount options | | `Protocol not supported` | Missing `nfs-common` or version mismatch | Install client package; align `vers=` | | Works manually, fails at boot | `remote-fs` / fstab options / network not ready | `_netdev`, `x-systemd.automount`, `remote-fs.target` | | `mount: can't find ... in /etc/fstab` | Wrong mount command shape | Missing source or target in the command | #### CIFS / SMB | Error / symptom | Common cause | Direction | |-----------------|--------------|-----------| | `mount error(13): Permission denied` | Credentials / share ACL | Check user, domain, credentials file mode `0600` | | `mount error(112): Host is down` / cannot connect | Host, firewall, SMB port 445 | `nc -zv <server> 445` | | `mount error(2): No such file or directory` | Wrong share/path | Verify `//server/share` | | `mount error(95): Operation not supported` | Dialect/version mismatch | Try `vers=3.0` / `2.1` / `1.0` (legacy) | | Missing `mount.cifs` | `cifs-utils` not installed | Debian/Ubuntu: `cifs-utils` | ### 3. Client environment (read-only) ```bash findmnt -t nfs,nfs4,cifs 2>/dev/null grep -E 'nfs|cifs|smb' /etc/fstab 2>/dev/null command -v mount.nfs; dpkg -l nfs-common 2>/dev/null | tail -1 lsmod | grep -E 'nfs|sunrpc' ls /etc/modprobe.d/*nfs* /etc/modprobe.d/*sunrpc* 2>/dev/null command -v mount.cifs; dpkg -l cifs-utils 2>/dev/null | tail -1 lsmod | grep cifs ``` ### 4. Connectivity (when server is known) ```bash getent ahosts <server> | head -5 ping -c 3 -W 2 <server> nc -zv -w 3 <server> 2049 nc -zv -w 3 <server> 111 rpcinfo -p <server> 2>/dev/null | head -20 showmount -e <server> 2>/dev/null | head -20 nc -zv -w 3 <server> 445 ``` Port/RPC issues → fix network/firewall before mount options. Resolve fails → consider `dns-diagnose`. ### 5. Example command shapes (suggestions only) ```bash sudo mount -t nfs -o vers=4,proto=tcp <server>:/export /mnt/point sudo mount -t nfs -o vers=3,proto=tcp <server>:/export /mnt/point sudo mount -t cifs //server/share /mnt/point -o username=<user>,uid=$(id -u),gid=$(id -g),vers=3.0 ``` Debian/Ubuntu client packages: `nfs-common`, `cifs-utils`. ## Output format ```text ## Conclusion 1–2 sentences: protocol + most likely cause. ## Evidence - User error text and matched pattern - Client packages/modules, fstab, port checks ## Recommendations - Prioritized fix steps (user confirms before running) - Never echo passwords into the chat or logs; remind about credential file permissions ``` Reply in the user's language. ## Related skills | Case | Skill | |------|-------| | DNS failure before mount | `dns-diagnose` | | Loss/latency to file server | `network-path-diagnose` | | System lag after a successful mount | `diagnose_system_lag` | ## Example **User**: `mount.nfs: access denied by server while mounting 10.0.0.5:/data/backup` 1. Candidates → export ACL / wrong path / possibly missing subdir 2. `showmount -e` / RPC checks; try export root only if appropriate 3. Root denied → server/client ACL; root works but `/backup` fails → fix subdir