When a file share is unmounted from Ubuntu Linux servers, you can check the logs to diagnose any issues in a couple of ways: using Syslog and dmesg.
Syslog:
You can find additional information related to mounting and unmounting in the syslog. Use the following command to search for relevant logs:
grep 'Mounted\\|Unmounted' /var/log/syslog*
This will display entries related to mounted and unmounted filesystems.
dmesg:
The dmesg command provides kernel ring buffer messages, including information about disk mounting.
To find logs related to mounting or ext4 filesystems, use:
grep -e mount -e ext4 -lR /var/log 2> /dev/null
Archived versions of dmesg logs are also available (e.g., dmesg.*).
Additionally, if you’re administering remote Ubuntu servers without a graphical interface, you can view log files directly from the terminal using:
tail -f /var/log/messages