What is machine-id
– The /etc/machine-id file contains the unique machine ID of the local system that is set during installation. The machine ID is a single newline-terminated, hexadecimal, 32-character, lowercase machine ID string. When decoded from hexadecimal, this corresponds to a 16-byte/128-bit string.
– The “machine-id” parameter is added from RHEL 7.1 to identify the machine in the network. Therefore this parameter must be unique.
– But when user clone the virtual machine that is installed RHEL 7.1, the cloned virtual machine’s “machine-id” is not changed, and some virtual machine may have the same “machine-id”.
– User should change the “machine-id” of the cloned virtual machine for the server to be uniquely identifiable over network.
– The machine-id is written into the file /etc/machine-id
# cat /etc/machine-id daab00e07fed481d8ccf145b7affc0c5
Changing the machine-id
1. Clear the original “machine-id”
– The “machine-id” value is written in “/etc/machine-id”.
– We can either remove or empty the machine-id file to clear out the original value.
# rm /etc/machine-id
2. Create the new “machine-id” value
Generate a new machine-id by the “systemd-machine-id-setup” command which populates the remove file again with a new and unique machine-id value.
# systemd-machine-id-setup Initializing machine ID from random generator.
Verify the new value of machine-id.
# cat /etc/machine-id 2175d9b2344a499abd87920c6f76f9a1