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Linux ENOSPC (errno 28) — No Space Left on Device (Deep Dive)

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About Linux ENOSPC (errno 28)

Deep dive into ENOSPC covering inode exhaustion, reserved blocks, journal space, tmpfs/RAM disk full, and Docker overlay filesystem space issues. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: ENOSPC can occur even when df shows free space — check inode usage with df -i. ext4 reserves 5% of space for root by default (tune2fs -m to adjust). Inode exhaustion: millions of tiny files can exhaust inodes while disk space remains. Docker: container overlay filesystem shares the host's /var/lib/docker partition. tmpfs (including /tmp, /dev/shm) is backed by RAM and has size limits. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Disk genuinely full from logs, downloads, or application data. Inodes exhausted — too many small files on the filesystem. Reserved blocks preventing non-root users from writing (ext4 5% reserve). Docker images and containers filling up /var/lib/docker. tmpfs (RAM disk) at capacity, especially /dev/shm for shared memory. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Check disk space: df -h and inode usage: df -i. Find large directories: du -sh /* | sort -rh | head -20. Clean Docker: docker system prune -a --volumes (removes unused images, containers, volumes). Reduce ext4 reserved blocks: sudo tune2fs -m 1 /dev/sdXY (reduce from 5% to 1%). Find and clean old log files: find /var/log -name '*.gz' -mtime +30 -delete. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Linux Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.

Quick Answer

Why does df show free space but I get ENOSPC?

Check inodes: df -i. Millions of tiny files can exhaust inodes while disk space remains. Also check if you are a non-root user hitting the 5% reserved blocks.

Overview

Deep dive into ENOSPC covering inode exhaustion, reserved blocks, journal space, tmpfs/RAM disk full, and Docker overlay filesystem space issues.

Key Details

  • ENOSPC can occur even when df shows free space — check inode usage with df -i
  • ext4 reserves 5% of space for root by default (tune2fs -m to adjust)
  • Inode exhaustion: millions of tiny files can exhaust inodes while disk space remains
  • Docker: container overlay filesystem shares the host's /var/lib/docker partition
  • tmpfs (including /tmp, /dev/shm) is backed by RAM and has size limits

Common Causes

  • Disk genuinely full from logs, downloads, or application data
  • Inodes exhausted — too many small files on the filesystem
  • Reserved blocks preventing non-root users from writing (ext4 5% reserve)
  • Docker images and containers filling up /var/lib/docker
  • tmpfs (RAM disk) at capacity, especially /dev/shm for shared memory

Steps

  1. 1Check disk space: df -h and inode usage: df -i
  2. 2Find large directories: du -sh /* | sort -rh | head -20
  3. 3Clean Docker: docker system prune -a --volumes (removes unused images, containers, volumes)
  4. 4Reduce ext4 reserved blocks: sudo tune2fs -m 1 /dev/sdXY (reduce from 5% to 1%)
  5. 5Find and clean old log files: find /var/log -name '*.gz' -mtime +30 -delete

Tags

linuxenospcerrno-28disk-fullinodes

More in Errno

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linux-errno-11-eagainLinux errno 11 (EAGAIN) — Resource Temporarily Unavailable
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linux-errno-12-enomemLinux errno 12 (ENOMEM) — Out of Memory
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linux-errno-13-eaccesLinux errno 13 (EACCES) — Permission Denied
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Frequently Asked Questions

Check inodes: df -i. Millions of tiny files can exhaust inodes while disk space remains. Also check if you are a non-root user hitting the 5% reserved blocks.