What the error looks like
Same error code, three different "full" conditions:
Error: ENOSPC: no space left on device, write
# the dev-server flavor:
Error: ENOSPC: System limit for number of file watchers reached
# docker:
failed to register layer: no space left on deviceDon't assume "disk full" — a disk with free space can still throw ENOSPC if it's out of inodes or if a watcher hit the inotify limit. Check all three.
Why it happens
The disk is genuinely full
Logs, build artifacts, or a runaway file filled the partition. df -h shows 100%.
Inodes are exhausted
Millions of tiny files used up all inodes while bytes remain. df -i shows 100% IUse.
Docker images and volumes piled up
Old images, dangling layers, and stopped containers quietly consume the disk.
inotify watch limit (dev)
A dev server watching many files hit max_user_watches — not a disk problem at all.
Diagnose it in three steps
Check space and inodes
df -h # bytes used
df -i # inodes used (a sneaky cause)Find what's eating it
du -sh /var/* 2>/dev/null | sort -h | tail
journalctl --disk-usage
docker system dfReclaim or raise the watch limit
# disk:
docker system prune -af --volumes
journalctl --vacuum-size=200M
# dev file-watcher limit:
sudo sysctl fs.inotify.max_user_watches=524288Stop the disk filling in the first place
Reclaiming space gets you running again; the durable fix is bounding what grows. Rotate logs, prune images on a schedule, and put high-churn data on a volume you monitor:
# rotate app/journal logs so they can't fill the root disk
# (logrotate, journald SystemMaxUse, or your platform's log limits)
# and alert before df hits ~85%, not at 100%.Bounded log handling and visible disk pressure
Runaway logs are a common cause of a full disk. Infraveil's customer-side launcher and agent run on your own servers, while the hosted management plane can surface selected logs, service status, and disk-related failures in one place. Retention, rotation, collection limits, and available disk space still depend on customer configuration and must be monitored; Infraveil does not guarantee that a disk cannot fill.
Frequently asked questions
What does ENOSPC mean?
A write failed because a resource is full. Most often the disk, but it can also be inode exhaustion or, in dev, the inotify file-watch limit.
My disk has space but I still get ENOSPC — why?
You're likely out of inodes (check df -i) from many tiny files, or you hit the inotify max_user_watches limit if it's a dev server.
How do I fix 'System limit for number of file watchers reached'?
Raise the limit: sudo sysctl fs.inotify.max_user_watches=524288 and persist it in /etc/sysctl.conf. It's a watcher limit, not a disk issue.
How do I reclaim Docker disk space?
Run docker system df to see usage, then docker system prune -af --volumes to remove unused images, containers, and volumes (be careful with --volumes).
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