Perhaps space marked as empty (e.g. deleted files) and seen as available at the datastore view but not to whatever you are checking that with in the lower pane?
Are these both measured at the same time and both 'up to date'?
What does df -h say? I would (unfortunately) always trust df as opposed to vSphere view.
VMFS3 - really?
Is your datastore attached to one host or multiple hosts?
If it's attached to mupltiple hosts then do rescan on all hosts and check numbers in vsphere client again. Because there could be differences between hosts and VC can return results from one of other hosts.
I have a similar situation.
When I check the full size of my virtual machines i get one data (below)
but when i check the same on vSphere there is an important difference.
To my understanding there should be at least 3 TB free.
Can anyone point me in right direction to understanding this situation?
Welcome to Communities! Some useful info on participating here:
Those appear to be the size of the VMs disks - this would not account for other files on the datastore such as snapshots and .vswp and/or anything else you have on there (e.g. ISOs) - check the usage via df -h.
.vswp are equal to the size of the RAM assigned to the VMs minus reservation.
Each level of snapshot can potentially grow to be the same size as their parent disk so do make sure you consolidate snapshots as soon as they are not needed - preferably only run on these for minutes/hours not days/weeks.