The Legacy Boot Accelerator
In older versions of Ubuntu (prior to the widespread adoption of fast NVMe solid-state drives), canonical introduced a service called ureadahead (Ubuntu Read-Ahead). During the system boot sequence, the operating system must read hundreds of small configuration files and shared libraries from the hard drive. On traditional spinning magnetic hard drives (HDDs), seeking out all these tiny files took a long time. The ureadahead daemon worked by profiling the boot process, figuring out exactly which files were needed, and then preemptively reading them into RAM in one massive, sequential chunk during the very beginning of the boot sequence.
While this significantly sped up boot times on mechanical hard drives, it is entirely obsolete on modern SSDs. Solid-state drives have near-zero seek times and can read thousands of small files instantly. Running ureadahead on a modern SSD actually slows the boot process down, as it introduces unnecessary CPU overhead and redundant I/O operations. Furthermore, it often conflicts with modern systemd startup parallelization. If you have this legacy daemon running on an SSD-equipped Ubuntu server, you must disable it.
How to Disable the Ureadahead Daemon
You can permanently stop this legacy caching service using systemctl.
Warning: Only perform this if your server is running on a Solid State Drive (SSD). If you are genuinely booting from an old spinning HDD, ureadahead might still be beneficial.
- Open your Ubuntu Terminal or connect via SSH.
- Stop the active daemon if it is currently running:
sudo systemctl stop ureadahead.service- Disable the service to prevent it from executing during the next boot sequence:
sudo systemctl disable ureadahead.service- (Optional) For a cleaner system, you can completely remove the package:
sudo apt-get purge ureadaheadYour Ubuntu system will now rely on systemd’s native, parallelized boot sequence, fully utilizing the random-read performance of your modern SSD.