Journal & Report: Saturn VM Disk Full and Container Failures
Date: 2026-01-14
VM Name: Saturn (VM-101)
Host: Proxmox
Services Affected: Home Assistant (HA), PostgreSQL, Plex Media Server
1. Incident Overview
While attempting to deploy the Home Assistant stack via Portainer, several failures occurred:
-
Home Assistant could not start because PostgreSQL exited with:
FATAL: could not write lock file "postmaster.pid": No space left on device -
Plex Media Server crashed with SQLite disk I/O errors:
sqlite3_statement_backend::prepare: disk I/O error for SQL: PRAGMA cache_size=2048 -
VM console showed Out of Memory errors.
2. Investigation
Commands executed:
df -h
lsblk
vgdisplay
lvdisplay
Findings:
- Root filesystem (
/) was completely full. - VM disk in Proxmox was 210 GB, but the Linux logical volume was only 148 GB.
- LVM volume group had no free extents initially.
- Disk exhaustion caused database corruption risks and service crashes.
3. Root Cause
- Docker images, volumes, Home Assistant data, and Plex metadata filled the root filesystem.
- LVM logical volume was not expanded after increasing VM disk size.
- Insufficient memory exacerbated system instability.
4. Resolution Steps
Step 1 — Resize VM Disk (Proxmox)
Increased VM disk size from 170 GB to 210 GB.
Step 2 — Resize Partition
sudo growpart /dev/sda 3
Step 3 — Resize Physical Volume
sudo pvresize /dev/sda3
Step 4 — Extend Logical Volume
sudo lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
Step 5 — Resize Filesystem
sudo resize2fs /dev/ubuntu-vg/ubuntu-lv
Step 6 — Increase VM Memory
Upgraded RAM from 4 GB to 8 GB.
Step 7 — Restart Services
Restarted PostgreSQL, Home Assistant, and Plex in dependency order.
Step 8 — Cleanup (Optional)
docker system prune -a --volumes -f
journalctl --vacuum-size=500M
5. Outcome
- Root filesystem expanded to ~205 GB.
- Over 100 GB of free space available.
- All services running normally.
- Disk and memory related failures resolved.
6. Recommendations
- Move Docker and application data to NFS or dedicated storage.
- Monitor disk usage proactively.
- Always expand LVM after resizing VM disks.
- Maintain sufficient RAM headroom for Plex and HA workloads.