An old thread, but the only one that comes up via Google. I just got this "Glusterd work directory dataset is not mounted" alert today. I have a brand new installation of TrueNAS-SCALE-23.10.2.
I'm running it on a Supermicro X13SCH-F motherboard and noticed that while the BMI IP address was still shown as connected to my network, the IP assigned to TrueNAS (via onboard ethernet port) was not. I don't know when that happened—I wasn't actively using the NAS and only noticed the issue when I tried to connect to its IP address on my LAN and that timed out. I logged into the BMI, but the remote console would not accept any input (the usual 1-9 for actions to perform). So, I chose "graceful shutdown" through the BMI and saw TrueNAS flash messages about unmounting disks, etc. The LAN itself appeared fine: the Internet worked, I could connect to other local devices, etc.
When I next powered on the system, the "glusterd work directory dataset is not mounted" alert was shown and the dashboard was missing information for CPU, Memory, and Network—these sections showed just spinning wheels. The storage section appeared normal. I could see my pools and datasets. The UI was responsive.
I chose "Restart" from the power menu and, after another reboot, things came back normally. No alert. All dashboard sections working.
I don't know what happened. The OS is installed on a Samsung 870 EVO 500GB SATA SSD. I have a single pool that consists of 2x4TB Samsung 990 PRO 4TB M.2 NVME drives in a mirror set connected directly to the motherboard. There are a couple users and one SMB share set up, but otherwise nothing else running. I'm still evaluating TrueNAS, so I planned to wipe this install and start from scratch anyway.
I'm just concerned because this is a clean install with a very simple setup and, well, things seem to be hanging and disconnecting already.