We had a power cut overnight, which resulted in datastore not being available when the server turned on.
When I checked the logs I see there was an error
Activation of logical volume pve/data is prohibited while logical volume pve/data_tmeta is active.
The local-lvm data storage was offline, the first thing I did was to restart the server.
I noticed the there was an error on the server console. The did boot but the Local-lvm data storage was still offline.
Time to start googling for a fix.
I came across this forum post, https://forum.proxmox.com/threads/task-error-activating-lv-pve-data-failed-activation-of-logical-volume-pve-data-is-prohibited-while-logical-volume-pve-data_tdata-is-active.106225/
It took an about 5 minutes for the lvchange -an pve/data_tmeta to work.
After I typed in the last command the data storage came up and I was able to power on the virtual machines.