The dm-event.service (Device Mapper event daemon, or dmeventd) is a system service in Ubuntu Server that monitors the status of device-mapper targets, such as LVM (Logical Volume Manager) mirrors, snapshots, or thin-provisioned pools. It listens for kernel events (like a mirror failure or a thin pool reaching capacity) and dynamically triggers user-space actions, such as extending a volume or notifying the administrator. While crucial for complex, dynamic LVM setups, this daemon is completely redundant on simple servers utilizing standard EXT4/XFS partitions directly on block devices (or standard hardware RAID without LVM), and it unnecessarily consumes memory and processing cycles.
This guide explains how to completely disable the dm-event service in Ubuntu Server, ensuring the system does not waste resources monitoring non-existent device-mapper configurations.
Stop and Mask the dm-event Service
Because systemd often utilizes socket activation for the Device Mapper event daemon, we must disable and mask both the service and its associated socket to ensure a permanent block.
- Log into your Ubuntu Server via SSH using an account with
sudoprivileges. - First, check if the service or socket is currently active:
sudo systemctl status dm-event.service dm-event.socket - Stop both the service and the socket immediately:
sudo systemctl stop dm-event.service dm-event.socket - Next, disable them to remove their symlinks from the systemd boot schedule:
sudo systemctl disable dm-event.service dm-event.socket - For absolute certainty, explicitly mask both units. This symlinks the unit files to
/dev/null, creating a hard block against them starting under any circumstances (even if LVM tools attempt to invoke them):sudo systemctl mask dm-event.service dm-event.socket
Verify the Service Lockdown
By masking dm-event.service and its socket, you guarantee that the Ubuntu OS will silently skip LVM event monitoring, optimizing the boot process and reducing background memory footprint on non-LVM servers.
To verify the lockdown is successful, attempt to start the service manually:
sudo systemctl start dm-event.serviceSystemd will return a fatal error stating that the unit is masked (e.g., Failed to start dm-event.service: Unit dm-event.service is masked). You can also run ps aux | grep dmeventd; the daemon will be entirely absent from the active process list, confirming your system is running a leaner, streamlined storage stack.